No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Cognitively Stimulating Environments and Cognitive Reserve: The Case of Personal Social Networks
Abstract
Cognitively stimulating environments are thought to be protective of cognitive decline and onset of Alzheimer's disease and related dementias (ADRD) through the development of cognitive reserve (CR). CR refers to cognitive adaptability that buffers the impact of brain pathology on cognitive function. Despite the critical need to identify cognitively stimulating environments to build CR, there is no consensus regarding which environmental determinants are most effective. Rather, most studies use education as proxies for CR and little is known about the association between older adults’ personal social networks and CR. Using neuroimaging data from 135 older adults participating in the Social Networks in Alzheimer Disease (SNAD) study, this article adopted a residual method for measuring CR and found that large network size, high network diversity, and loosely connected networks were positively associated with greater CR. These results suggest that expansive social networks in later life may constitute cognitively stimulating environments which can be leveraged to build CR and reduce the burden of ADRD.
... Finally, we are the first known research team to examine the association between occupational complexity and a measure of brain reserve 68 derived from the residual of the association between structural neuroimaging biomarkers and global cognitive function. 69 We employ data from a unique source, the Social Networks in Alzheimer Disease (SNAD) study, a collaboration with the Indiana Alzheimer's Disease Research Center (IADRC). The majority of study participants are retired (mean age: 70.8) and are no longer working in their longest-held job. ...
... Finally, we included a measure of brain reserve derived from Peng et al. (2022). 69 ...
... MCI and dementia were diagnosed by a consensus of IADRC clinicians and study personnel. Brain reserve was computed using the residualization method described in Peng et al. 202269 (see details below). All other cognitive outcomes were derived from the NACC UDS Neuropsychological Battery. ...
Individuals with more complex jobs experience better cognitive function in old age and a lower risk of dementia, yet complexity has multiple dimensions. Drawing on the Social Networks in Alzheimer Disease study, we examine the association between occupational complexity and cognition in a sample of older adults (N = 355). A standard deviation (SD) increase in complex work with people is associated with a 9% to 12% reduction in the probability of mild cognitive impairment or dementia, a 0.14-0.19 SD increase in episodic memory, and a 0.18-0.25 SD increase in brain reserve, defined as the gap (residual) between global cognitive function and magnetic resonance imaging (MRI) indicators of brain atrophy. In contrast, complexity with data or things is rarely associated with cognitive outcomes. We discuss the clinical and methodological implications of these findings, including the need to complement data-centered activities (e.g., Sudoku puzzles) with person-centered interventions that increase social complexity.
... At an aggregate level, research has found that increased social engagement serves to protect against ADRD symptoms (Majoka & Schimming, 2021). Social network characteristics can alter the degree of this protective effect, with larger and more diverse social networks contributing more to cognitive reserve and cognitively stimulating social environments (Peng et al., 2022). An individual's level of social engagement in later life is particularly important in combating ADRD risks, since symptoms begin to manifest in this time period (Saczynski et al., 2006). ...
... Research in Western contexts has confirmed an association between social engagement and improved cognitive health (Majoka & Schimming, 2021;Peng et al., 2022;Saczynski et al., 2006;Salinas et al., 2022). Our study confirms this association in an Asian country with a large older adult population. ...
Objective:
Vietnam is an LMIC in Asia that is experiencing rising cases of Alzheimer's disease and related dementias (ADRD). Many Vietnamese adults at risk of ADRD have experienced early-life war exposures, which may have negative impacts on their cognitive function in later years.
Methods:
Our study uses the Vietnam Health and Aging Study (VHAS) to investigate the impact of early-life war exposure on cognitive function in later life while also considering variations in social engagement. The sample consists of 2352 adults aged 60 and older from northern and central Vietnam. Cognitive function, measured by questions from the Mini Mental State Examination (MMSE), and self-rated memory are our dependent variables and five measures related to social engagement serve as independent variables.
Results:
Our results show an association between PTSD symptoms and poorer cognitive function (0.0704, p < 0.05) and self-rated memory (OR = 0.904, p < 0.001; 95%). Similar results are also found among for individuals with lower level of social engagement. Furthermore, several sociodemographic factors exhibit attenuated effects on cognitive function due to variations in social engagement.
Conclusion:
Social engagement is generally beneficial for cognitive health amongst those with early-life war exposure, but it does not necessarily attenuate the effects of trauma.
... From the perspective of brain evolution, the individual's need for emotion directly or indirectly contributes to generating a particular neuronal network and improves cognition [39]. Additionally, broad social networks in later life may aid cognitive reserve creation [36] and minimize dementia risk [40,41]. Social networks can act as cognitive stimulation for elderly people. ...
Background
The development and popularization of the Internet provides an important opportunity to advance national strategies for healthy aging, particularly the impact of the Internet on cognitive function in middle-aged and older adults.
Objective
This study aimed to quantify the impact of Internet use on the cognitive health of middle-aged and older adults (aged≥45 years).
Methods
We used data from the Chinese Family Panel Study (CFPS) survey, tested the robustness of the baseline findings by variable substitution and instrumental variables methods, and analyzed heterogeneity. Subsequently, five purposes of Internet use that affect cognitive function were analyzed in depth.
Results
Internet use may improve cognitive function in middle-aged and older adults. The effect of Internet use on cognitive function was more pronounced in the lower age group (45–59 years), among males, in rural areas, and among middle-aged and older adults with higher levels of education. Cognitive functioning of middle-aged and older adults varied according to how often they used the Internet for entertainment, socialization, study, work, and business activities.
Conclusions
The use of the Internet may be considered a practical non-pharmacological intervention to slow cognitive decline in middle-aged and older adults.
... For instance, prior authors have opined on the increased cognitive demand necessary for maintaining friendships and friend-based dialogues and conversations, such as memory, planning, inhibition, and processing speed (Kelly et al., 2017). Regularly using cognitive skills to maintain friendships may prime the brain to efficiently use remaining neuroanatomical resources that are not yet affected by neuroinflammation (Peng et al., 2022). That is, friendships may offer a form of regular cognitive exercise useful for optimizing cognitive health and can offset inflammation-mediated neuronal decay. ...
Background
Cognitive aging is a complex process that impacts human behavior. Identifying the factors that preserve cognitive functioning is a public health priority, given that 20% of the US population will be at least 65 years old in the next decade. Biopsychosocial determinants of cognitive decline across the lifespan are often examined as ecological factors that independently moderate cognitive aging, despite the known complexity surrounding these relationships.
Objective
We aimed to address this gap by exploring the synergistic and simultaneous relationship between risk and protective factors on cognitive functioning.
Method
Using the MIDUS study datasets, we examined the relationships among physiological markers, friendship quality, and global cognition functioning, concurrently and longitudinally over ten years. Our participants included 929 healthy (417 men, 512 women) adults (average age at Time 1: 54.6 ± 11.6 years). Exploratory analyses examining the effects of racial minority status were also conducted.
Results
Cross-sectionally, age, and friendship quality moderated the relationship between vagally-mediated heart rate variability (vm-HRV) and cognition such that younger adults with greater friendship quality had a negative relationship between vm-HRV and cognitive performance; our unexpected finding suggests the heart-brain relationship is sensitive to the biopsychosocial environment. Longitudinally, higher IL-6 levels at Time 1 predicted poorer cognitive performance a decade later, but only among those with greater levels of friendship quality, especially for white-identifying individuals.
Conclusions
The relationships among physiological risk factors, social protective factors and cognitive functioning appear to be temporally different during mid-adulthood. Given many of the whole sample findings were not replicated within the racial minority subgroup, we suggest that these relationships should be examined in a larger and more diverse racial minority sample to determine whether this study lacked the power necessary to detect a relationship or if the relationships are in fact different by racial minority sub-group. In addition, future research should overcome the study's reliance on healthy adults and self-report measures of friendship quality by including adults with pre-existing cognitive impairments, and employing more real-time measures of friendship quality, such as daily diary or ecological momentary assessment.
Aim
We investigated the effect of lifespan cognitive reserve and its components on cognitive frailty among older adults.
Methods
A total of 4922 participants aged ≥65 years were recruited in 2008 and were followed up in 2011 from the Chinese Longitudinal Healthy Longevity Survey. Cognitive frailty was determined through the simultaneous presence of physical frailty (pre‐frailty or frailty) and mild cognitive impairment, excluding concurrent dementia. The assessment of physical frailty and mild cognitive impairment was based on the Fatigue, Resistence, Ambulation, Illness, Loss of weight (FRAIL) (Fatigue, Resistence, Ambulation, Illness, Loss) and Mini‐Mental State Examination scale, respectively. The lifespan cognitive reserve consisted of education attainment, occupational complexity and later‐life leisure activities. We used logistic regression models to estimate the risk of cognitive frailty associated with the lifespan cognitive reserve and its components.
Results
A higher level of lifespan cognitive reserve, higher educational attainment or leisure activities engagement, but not occupational complexity, were associated with lower risk of incident cognitive frailty. Furthermore, cognitive, social and physical activities were associated with lower risk of incident cognitive frailty.
Conclusion
Cognitive reserve, particularly educational attainment and leisure activities, can protect from cognitive frailty. This implicates that individuals should accumulate cognitive reserve in their lifespan, and older adults should actively participate in leisure activities to prevent cognitive frailty. Geriatr Gerontol Int 2024; ••: ••–•• .
Objectives
Sensory health declines with age but remains critical to the navigation and enjoyment of everyday life. Neighborhoods are key sites of environmental exposure, social engagement, and access to resources that can shape sensory health, yet the residential neighborhood is understudied as a determinant of sensory function.
Methods
We use data from Rounds 1 and 2 of the National Social Life, Health, and Aging Project (NSHAP) to examine how subjective and objective measures of older adults’ residential areas are associated with sensory health in a series of cross-sectional and multilevel regression models.
Results
In cross-sectional models, higher levels of perceived neighborhood social ties are associated with significantly better self-rated vision. Older adults who reside in more densely populated tracts are more likely to have significantly worse olfactory identification, whereas residing in tracts with higher levels of concentrated disadvantage is associated with significantly lower levels of self-rated vision. In multilevel models, residing in more densely populated tracts is associated with significantly worse olfactory identification, while tract-level concentrated disadvantage is associated with significantly worse hearing and vision.
Discussion
We propose that neighborhood characteristics could influence certain environmental exposures, the amount of time that older adults spend out of the home, patterns of social engagement, and access to preventative care that affect sensory health. Residential neighborhoods may be important sites of potential intervention to slow age-related sensory declines and other related conditions.
Objectives:
This study examined the association between number of children and cognitive function and its possible hormone and psychosocial pathways in Chinese menopausal women.
Methods:
We analyzed data from the China Health and Retirement Longitudinal Study (CHALRS), including 4803 menopausal women. Ordinary least squares (OLS) regression modeling and structural equation models (SEMs) were applied to explore the association between number of children and cognitive function and the potential mechanisms.
Results:
Overall, the median number of biological children was three among participants. The cognitive function score decreased significantly with increasing numbers of children (β = -0.547, 95 % CI: -0.677, -0.416). There was a significant interaction between number of children and residence (P = 0.003). Compared with older women with three or less children, women with more than three children had worse cognitive function (β = -0.798, 95 % CI: -1.081, -0.514). Mediation analysis verified that depressive symptoms and social participation partially mediate the associations between the number of children and cognitive function.
Limitations:
Because of the cross-sectional design, our study was unable to make causal inferences. Second, information about endogenous estrogen exposure was not collected in CHARLS. In addition, recall bias may exist due to the use of self-reported data.
Conclusion:
Our results indicated that a higher number of children is associated with an increased risk for cognitive impairment. We suggest paying special attention to mental and social health among women with multiple children (>3).
Importance:
Lifestyles enriched with socially and mentally stimulating activities in older age may help build cognitive reserve and reduce dementia risk.
Objective:
To investigate the association of leisure activities and social networks with dementia risk among older individuals.
Design, setting, and participants:
This longitudinal prospective cohort study used population-based data from the ASPREE Longitudinal Study of Older Persons (ALSOP) for March 1, 2010, to November 30, 2020. Community-dwelling individuals in Australia aged 70 years or older who were generally healthy and without major cognitive impairment at enrollment were recruited to the ALSOP study between March 1, 2010, and December 31, 2014. Data were analyzed from December 1, 2022, to March 31, 2023.
Exposures:
A total of 19 measures of leisure activities and social networks assessed at baseline were classified using exploratory factor analysis.
Main outcomes and measures:
Dementia was adjudicated by an international expert panel according to Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) criteria. Cox proportional hazards regression examined dementia risk over 10 years, adjusting for education, socioeconomic status, and a range of health-related factors.
Results:
This study included 10 318 participants. Their median age was 73.8 (IQR, 71.6-77.2) years at baseline, more than half (52.6%) were women, and most self-identified as White (98.0%). In adusted analyses, more frequent engagement in adult literacy activities (eg, writing letters or journaling, using a computer, and taking education classes) and in active mental activities (eg, playing games, cards, or chess and doing crosswords or puzzles) was associated with an 11.0% (adjusted hazard ratio [AHR], 0.89 [95% CI, 0.85-0.93]) and a 9.0% (AHR, 0.91 [95% CI, 0.87-0.95]) lower risk of dementia, respectively. To a lesser extent, engagement in creative artistic activities (craftwork, woodwork, or metalwork and painting or drawing) (AHR, 0.93 [95% CI, 0.88-0.99]) and in passive mental activities (reading books, newspapers, or magazines; watching television; and listening to music or the radio) (AHR, 0.93 [95% CI, 0.86-0.99]) was also associated with reduced dementia risk. In contrast, interpersonal networks, social activities, and external outings were not associated with dementia risk in this sample.
Conclusions and relevance:
These results suggest that engagement in adult literacy, creative art, and active and passive mental activities may help reduce dementia risk in late life. In addition, these findings may guide policies for geriatric care and interventions targeting dementia prevention for older adults.
Alzheimer disease is one of the most challenging demons in our society due to its very high prevalence and its clinical manifestations which cause deterioration of cognition, intelligence, and emotions - the very capacities that distinguish Homo sapiens from other animal species. Besides the personal, social, and economical costs, late stages of AD are vivid experiences for the family, relatives, friends, and general observers of the progressive ruin of an individual who turns into a being with lower mental and physical capacities than less evolved species. A human brain with healthy cognition, conscience, and emotions can succeed in dealing with most difficulties that life may pose. Without these capacities, the same person probably cannot. Due, in part, to this emotional impact, the absorbing study of AD has generated, over the years, a fascinating and complex story of theories, hypotheses, controversies, fashion swings, and passionate clashes, together with tremendous efforts and achievements geared to improve understanding of the pathogenesis and treatment of the disorder. Familal AD is rare and linked to altered genetic information associated with three genes. Sporadic AD (sAD) is much more common and multifactorial. A major point of clinical discussion has been, and still is, establishing the differences between brain aging and sAD. This is not a trivial question, as the neuropathological and molecular characteristics of normal brain aging and the first appearance of early stages of sAD-related pathology are not easily distinguishable in most individuals. Another important point is confidence in assigning responsibility for the beginning of sAD to a few triggering molecules, without considering the wide number of alterations that converge in the pathogenesis of aging and sAD. Genetic risk factors covering multiple molecular signals are increasing in number. In the same line, molecular pathways are altered at early stages of sAD pathology, currently grouped under the aegis of normal brain aging, only to increase massively at advanced stages of the process. Sporadic AD is here considered an inherent, natural part of human brain aging, which is prevalent in all humans, and variably present or not in a few individuals in other species. The progression of the process has devastating effects in a relatively low percentage of human beings eventually evolving to dementia. The continuum of brain aging and sAD implies the search for a different approach in the study of human brain aging at the first stages of the biological process, and advances in the use of new technologies aimed at slowing down the molecular defects underlying human brain aging and sAD at the outset, and transfering information and tasks to AI and coordinated devices.
Alzheimer's disease (AD)-related neurofibrillary tangles (NFT), argyrophilic grain disease (AGD), aging-related tau astrogliopathy (ARTAG), limbic predominant TDP-43 proteinopathy (LATE), and amygdala-predominant Lewy body disease (LBD) are proteinopathies that, together with hippocampal sclerosis, progressively appear in the elderly affecting from 50% to 99% of individuals aged 80 years, depending on the disease. These disorders usually converge on the same subject and associate with additive cognitive impairment. Abnormal Tau, TDP-43, and α-synuclein pathologies progress following a pattern consistent with an active cell-to-cell transmission and abnormal protein processing in the host cell. However, cell vulnerability and transmission pathways are specific for each disorder, albeit abnormal proteins may co-localize in particular neurons. All these alterations are unique or highly prevalent in humans. They all affect, at first, the archicortex and paleocortex to extend at later stages to the neocortex and other regions of the telencephalon. These observations show that the phylogenetically oldest areas of the human cerebral cortex and amygdala are not designed to cope with the lifespan of actual humans. New strategies aimed at reducing the functional overload of the human telencephalon, including optimization of dream repair mechanisms and implementation of artificial circuit devices to surrogate specific brain functions, appear promising.
Purpose of review:
Poor cognitive aging and dementia pose a significant public health burden, and women face unique risks compared to men. Recent research highlights the role of genetics, menopause, chronic disease, and lifestyle in risk and resilience in women's cognitive aging. This work suggests avenues for clinical action at midlife that may change the course of brain health in aging.
Recent findings:
Studies indicate women's risk for poor cognitive aging relates in part to hormone changes at menopause, a time when memory, brain structure and function, and Alzheimer's pathology may be observed in women and not men. Medical and lifestyle risks including diabetes, hypertension, and low physical activity also contribute to women's unique risks. At the same time, literature on resilience suggests women may benefit from lifestyle and chronic disease intervention, possibly more than men. Current studies emphasize the importance of interacting genetic and lifestyle risks, and effects of social determinants of health.
Summary:
Women have greater risk than men for poor cognitive aging; however, by treating the whole person, including genetics, lifestyle, and social environment, clinicians have an opportunity to support healthy cognitive aging in women and reduce the future public health burden of dementia.
Studies in the neurotypical population have demonstrated that personal social networks can mitigate cognitive decline and the development of Alzheimer disease. To assess whether these benefits can also be extended to people with Down syndrome (DS), we studied whether and how personal networks can be measured in this population. We adapted a personal networks instrument previously created, validated, and implemented for the neurotypical population. We created two versions of the survey: one for participants with DS, ages 25 and older, and another for their study partners, who spent a minimum of 10 h/wk in a caregiver role. Participants with DS gave concordant data to those of study partners. Their personal networks included a median network size of 7.50, density 0.80, constraint 46.00, and effective size 3.07. Personal networks were composed of 50% kin, 80% who live within 15 miles, and 80% who eat a healthy diet. In this proof‐of‐principle study, we demonstrated that the personal networks of people with DS can be quantitatively analyzed, with no statistical difference between self‐report and parent‐proxy report. Future research efforts can now evaluate interventions to enhance personal networks for preventing Alzheimer disease in this population.
Introduction:
Federally funded Alzheimer's Disease Centers in the United States have been using a standardized neuropsychological test battery as part of the National Alzheimer's Coordinating Center Uniform Data Set (UDS) since 2005. Version 3 (V3) of the UDS replaced the previous version (V2) in 2015. We compared V2 and V3 neuropsychological tests with respect to their ability to distinguish among the Clinical Dementia Rating (CDR) global scores of 0, 0.5, and 1.
Methods:
First, we matched participants receiving V2 tests (V2 cohort) and V3 tests (V3 cohort) in their cognitive functions using tests common to both versions. Then, we compared receiver-operating characteristic (ROC) area under the curve in differentiating CDRs for the remaining tests.
Results:
Some V3 tests performed better than V2 tests in differentiating between CDR 0.5 and 0, but the improvement was limited to Caucasian participants.
Discussion:
Further efforts to improve the ability for early identification of cognitive decline among diverse racial groups are required.
Objectives: Characterized by infrequent contact, low emotional intensity, and limited intimacy, weak ties are found to be associated with better subjective well-being and other health outcomes. Drawing on the theory of weak ties and the convoy model of social relations, this paper aims to examine the association between weak ties and cognitive function among older adults in China.
Methods: We used multilevel growth modeling to analyze panel data for adults aged 60 years and over (N = 2,650) selected from the China Health and Retirement Longitudinal Study (CHARLS, 2011–2015). Weak ties were measured based on the frequency of social activity participation and the number of social activities.
Results: Weekly or irregular social activity participation in at least one social activity was significantly associated with better mental status and memory. The number of participated social activities was also significantly and positively associated with mental status and memory. After controlling for age, gender, marital status, educational attainment, geographic residence, household expenditures, and health conditions (i.e., depressive symptoms and self-reported health), we found that participation in a greater number of social activities protected memory from declining by 4% for every 2 years (p < 0.001).
Conclusion: These findings suggest that social interactions with peripheral members of a diverse social network may help prevent cognitive decline for older Chinese adults. Greater attention on weak ties might yield practical implications for non-pharmacological dementia prevention and health promotion for the general older population.
One of the fundamental challenges for neuropsychological aging research is how to maintain and promote cognitive functioning in old age. Previous research revealed that an active lifestyle, social participation, and emotional support during adulthood seem to be protective against cognitive decline in old age. However, up to now, a detailed examination of the interplay of these relations based on a broader variety of past activities and considering the individual’s available social capital is missing. The present study seeks to extend the literature by investigating the interactions of family based social capital as a mediator between the build-up of cognitive reserve (via the engagement in a broad variety of past leisure activities) and old age cognitive functioning in a large sample of older adults with a wide age range. A total of 2,788 older adults (aged 65–101 years) served as the sample for the present study. A test on verbal abilities, one on processing speed and one on cognitive flexibility were applied. In addition, individuals were retrospectively interviewed regarding their family network and regarding received and given support within it, as well as regarding 18 leisure activities (carried out at age 45). Present results suggest that network size as well as the given support within the family network mediate the relation between having an active lifestyle during middle adulthood and better cognitive functioning in old age. These findings are discussed with respect to models of cognitive reserve and cognitive aging.
The human social brain is complex. Current knowledge fails to define the neurobiological processes underlying social behaviour involving the (patho-) physiological mechanisms that link system-level phenomena to the multiple hierarchies of brain function. Unfortunately, such a high complexity may also be associated with a high susceptibility to several pathogenic interventions. Consistently, social deficits sometimes represent the first signs of a number of neuropsychiatric disorders including schizophrenia (SCZ), Alzheimer's disease (AD) and major depressive disorder (MDD), which lead to a progressive social dysfunction. In the present review we summarize present knowledge linking neurobiological substrates sustaining social functioning, social dysfunction and social withdrawal in major psychiatric disorders. Interestingly, AD, SCZ, and MDD affect the social brain in similar ways. Thus, social dysfunction and its most evident clinical expression (i.e., social withdrawal) may represent an innovative transdiagnostic domain, with the potential of being an independent entity in terms of biological roots, with the perspective of targeted interventions.
Contemporary imaging measures of the human brain explain less than half of the differences in cognitive functioning and change among older adults. Researchers have advanced several theories and concepts to guide research that aims to better explain these individual differences in cognitive aging. Taking the fundamental measurement model in the empirical sciences as a starting point, we here scrutinize two such complementary theories, brain maintenance and cognitive reserve, in an attempt to clarify these theories, gauge their usefulness, and identify ways in which they can be further developed. We demonstrate that, although both theories are highly useful for spawning theorizing and empirical work, they can be further developed by detailing the theoretical and operational definitions of the concepts that they propose. We propose a few ways forward in these directions.
Background
Social relationships, which are contingent on access to social networks, promote engagement in social activities and provide access to social support. These social factors have been shown to positively impact health outcomes. In the current systematic review, we offer a comprehensive overview of the impact of social activities, social networks and social support on the cognitive functioning of healthy older adults (50+) and examine the differential effects of aspects of social relationships on various cognitive domains. Methods
We followed PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines, and collated data from randomised controlled trials (RCTs), genetic and observational studies. Independent variables of interest included subjective measures of social activities, social networks, and social support, and composite measures of social relationships (CMSR). The primary outcome of interest was cognitive function divided into domains of episodic memory, semantic memory, overall memory ability, working memory, verbal fluency, reasoning, attention, processing speed, visuospatial abilities, overall executive functioning and global cognition. ResultsThirty-nine studies were included in the review; three RCTs, 34 observational studies, and two genetic studies. Evidence suggests a relationship between (1) social activity and global cognition and overall executive functioning, working memory, visuospatial abilities and processing speed but not episodic memory, verbal fluency, reasoning or attention; (2) social networks and global cognition but not episodic memory, attention or processing speed; (3) social support and global cognition and episodic memory but not attention or processing speed; and (4) CMSR and episodic memory and verbal fluency but not global cognition. Conclusions
The results support prior conclusions that there is an association between social relationships and cognitive function but the exact nature of this association remains unclear. Implications of the findings are discussed and suggestions for future research provided. Systematic review registrationPROSPERO 2012: CRD42012003248.
Background
The concept of Cognitive Reserve has great appeal and has led to an interesting and important body of research. We believe, however, that it is unnecessarily limited by ‘habits’ of measurement, nomenclature, and intra-disciplinary thinking. Main bodyA broader, more comprehensive way of conceptualizing Reserve is proposed that invokes a broader measurement approach, nomenclature that uses specific terms embedded in a theoretical model, and crosses disciplines. Conclusion
Building on this comprehensive conceptualization, we will discuss fruitful directions for future research.
Background:
Loneliness is a significant concern among the elderly, particularly in societies with rapid growth in aging populations. Loneliness may influence cognitive function, but the exact nature of the association between loneliness and cognitive function is poorly understood. The purpose of this systematic review was to synthesize current findings on the association between loneliness and cognitive function in older adults.
Method:
A comprehensive, electronic review of the literature was performed. Criteria for inclusion were original quantitative or qualitative research, report written in English, human participants with a mean age ≥ 60 years, and published from January 2000 through July 2013. The total number of studies included in this systematic review was ten.
Results:
Main findings from the ten studies largely indicate that loneliness is significantly and negatively correlated with cognitive function, specifically in domains of global cognitive function or general cognitive ability, intelligence quotient (IQ), processing speed, immediate recall, and delayed recall. However, some initial correlations were not significant after controlling for a wide range of demographic and psychosocial risk factors thought to influence loneliness.
Conclusions:
Greater loneliness is associated with lower cognitive function. Although preliminary evidence is promising, additional studies are necessary to determine the causality and biological mechanisms underlying the relationship between loneliness and cognitive function. Findings should be verified in culturally diverse populations in different ages and settings using biobehavioral approaches.
Cognitive reserve is thought to reflect life experiences. Which experiences contribute to reserve and their relative importance is not understood. Subjects were 652 autopsied cases from the Rush Memory and Aging Project and the Religious Orders Study. Reserve was defined as the residual variance of the regressions of cognitive factors on brain pathology and was captured in a latent variable that was regressed on potential determinants of reserve. Neuropathology variables included Alzheimer's disease markers, Lewy bodies, infarcts, microinfarcts, and brain weight. Cognition was measured with six cognitive domain scores. Determinants of reserve were socioeconomic status (SES), education, leisure cognitive activities at age 40 (CA40) and at study enrollment (CAbaseline) in late life. The four exogenous predictors of reserve were weakly to moderately inter-correlated. In a multivariate model, all except SES had statistically significant effects on Reserve, the strongest of which were CA40 (β = .31) and CAbaseline (β = .28). The Education effect was negative in the full model (β = -.25). Results suggest that leisure cognitive activities throughout adulthood are more important than education in determining reserve. Discrepancies between cognitive activity and education may be informative in estimating late life reserve. (JINS, 2011, 17, 615-624).
In later adulthood brain pathology becomes common and trajectories of cognitive change are heterogeneous. Among the multiple determinants of late-life cognitive course, cognitive reserve has been proposed as an important factor that modifies or buffers the impact of brain pathology on cognitive function. This article presents and investigates a novel method for measuring and investigating such factors. The core concept is that in a population where pathology is common and variably present, 'reserve' may be defined as the difference between the cognitive performance predicted by an individual's level of pathology and that individual's actual performance. By this definition, people whose measured cognitive performance is better than predicted by pathology have high reserve, whereas those who perform worse than predicted have low reserve. To test this hypothesis, we applied a latent variable model to data from a diverse ageing cohort and decomposed the variance in a measure of episodic memory into three components, one predicted by demographics, one predicted by pathology as measured by structural MRI and a 'residual' or 'reserve' term that included all remaining variance. To investigate the plausibility of this approach, we then tested the residual component as an operational measure of reserve. Specific predictions about the effects of this putative reserve measure were generated from a general conceptual model of reserve. Each was borne from the results. The results show that the current level of reserve, as measured by this decomposition approach, modifies rates of conversion from mild cognitive impairment to dementia, modifies rates of longitudinal decline in executive function and, most importantly, attenuates the effect of brain atrophy on cognitive decline such that atrophy is more strongly associated with cognitive decline in subjects with low reserve than in those with high reserve. Decomposing the variance in cognitive function scores offers a promising new approach to the measure and study of cognitive reserve.
We examined the association of diverse measures of social engagement with level of function in multiple cognitive domains in 838 persons without dementia who had a mean age of 80.2 (SD = 7.5). Social network size, frequency of social activity, and level of perceived social support were assessed in linear regression models adjusted for age, sex, education, and other covariates. Social activity and social support were related to better cognitive function, whereas social network size was not strongly related to global cognition. The results confirm that higher level of social engagement in old age is associated with better cognitive function but the association varies across domains of social engagement.
On the basis of postulates derived from socioemotional selectivity theory, the authors explored the extent to which future time perspective (FTP) is related to social motivation, and to the composition and perceived quality of personal networks. Four hundred eighty German participants with ages ranging from 20 to 90 years took part in the study. In 2 card-sort tasks, participants indicated their partner preference and goal priority. Participants also completed questionnaires on personal networks and social satisfaction. Older people, as a group, perceived their future time as more limited than younger people. Individuals who perceived future time as being limited prioritized emotionally meaningful goals (e.g., generativity, emotion regulation), whereas individuals who perceived their futures as open-ended prioritized instrumental or knowledge-related goals. Priority of goal domains was found to be differently associated with the size, composition, and perceived quality of personal networks depending on FTP. Prioritizing emotion-regulatory goals was associated with greater social satisfaction and less perceived strain with others when participants perceived their future as limited. Findings underscore the importance of FTP in the self-regulation of social relationships and the subjective experience associated with them.
The idea of reserve against brain damage stems from the repeated observation that there does not appear to be a direct relationship between the degree of brain pathology or brain damage and the clinical manifestation of that damage. This paper attempts to develop a coherent theoretical account of reserve. One convenient subdivision of reserve models revolves around whether they envision reserve as a passive process, such as in brain reserve or threshold, or see the brain as actively attempting to cope with or compensate for pathology, as in cognitive reserve. Cognitive reserve may be based on more efficient utilization of brain networks or of enhanced ability to recruit alternate brain networks as needed. A distinction is suggested between reserve, the ability to optimize or maximize normal performance, and compensation, an attempt to maximize performance in the face of brain damage by using brain structures or networks not engaged when the brain is not damaged. Epidemiologic and imaging data that help to develop and support the concept of reserve are presented.
Background and objectives:
Social connectedness has been linked prospectively to cognitive aging, but there is little agreement about the social mechanisms driving this relationship. This study evaluated nine measures of social connectedness, focusing on two forms of social enrichment - access to an expansive and diverse set of loosely connected individuals (i.e., social bridging) and integration in a supportive network of close ties (i.e., social bonding).
Research design and methods:
This study used egocentric network and cognitive data from 311 older adults in the Social Networks in Alzheimer Disease (SNAD) study. Linear regressions were used to estimate the association between social connectedness and global cognitive function, episodic memory, and executive function.
Results:
Measures indicative of social bridging (larger network size, lower density, presence of weak ties, and proportion non-kin) were consistently associated with better cognitive outcomes, while measures of social bonding (close ties, multiplex support, higher frequency of contact, better relationship quality, and being married) largely produced null effects.
Discussion and implications:
These findings suggest that the protective benefits of social connectedness for cognitive function and memory may operate primarily through a cognitive reserve mechanism that is driven by irregular contact with a larger and more diverse group of peripheral others.
Although it is widely accepted that personal networks influence health and illness, network recall remains a major concern. This concern is heightened when studying a population that is vulnerable to cognitive decline. Given these issues, we use data from the Social Network in Alzheimer Disease project to explore similarities and discrepancies between the network perceptions of focal participants and study partners. By leveraging data on a sample of older adults with normal cognition, mild cognitive impairment, and early stage dementia, we explore how cognitive impairment influences older adults' perceptions of their personal networks. We find that the average individual is more likely to omit weaker, peripheral ties from their self-reported networks than stronger, central ties. Despite observing only moderate levels of focal-partner corroboration across our sample, we find minimal evidence of perceptual differences across diagnostic groups. We offer two broad conclusions. First, self-reported network data, though imperfect, offer a reasonable account of the core people in one's life. Second, our findings assuage concerns that cognitively impaired older adults have skewed perceptions of their personal networks.
Late life is a period frequently marked by decline in personal health and heightened need for social support. Consequently, the social networks in which individuals are embedded assume an increasingly central role in the health and wellbeing of older adults. In the present article, I review the state of the literature on social networks and health in later life. By drawing on insights from the sociology of ageing and the life course, I address new developments and current challenges within the field. Chief among these developments and challenges is the recognition that the ageing process does not occur in a vacuum. Rather, individuals are consistently exposed to numerous changes to their social lives which have strong implications for current and future health outcomes. Upon highlighting the latest innovations within the field of networks and health, I conclude with useful directions for future research.
Several concepts, which in the aggregate get might be used to account for "resilience" against age- and disease-related changes, have been the subject of much research. These include brain reserve, cognitive reserve, and brain maintenance. However, different investigators have use these terms in different ways, and there has never been an attempt to arrive at consensus on the definition of these concepts. Furthermore, there has been confusion regarding the measurement of these constructs and the appropriate ways to apply them to research. Therefore the reserve, resilience, and protective factors professional interest area, established under the auspices of the Alzheimer's Association, established a whitepaper workgroup to develop consensus definitions for cognitive reserve, brain reserve, and brain maintenance. The workgroup also evaluated measures that have been used to implement these concepts in research settings and developed guidelines for research that explores or utilizes these concepts. The workgroup hopes that this whitepaper will form a reference point for researchers in this area and facilitate research by supplying a common language.
Background
Having a larger social network has been shown to have beneficial effects on health and survival in adults, but few studies have evaluated the role of network diversity, in addition to network size. We explore whether social network diversity is associated with mortality, cognition and physical function among older black and white adults.
Methods
Data are obtained from the Chicago Health and Aging Project, a longitudinal, population-based study of adults aged 65 years and older at baseline. Using Cox proportional hazards regression, we estimate the hazard of mortality by network diversity (n=6497). The association between network diversity and cognition (n=6560) and physical function (n=6561) is determined using generalised estimating equations. Models were adjusted for age, gender, race, socioeconomic status, marital status and health-related variables.
Results
In fully adjusted models, elderly with more diverse social networks had a lower risk of mortality (HR=0.93, p<0.01) compared with elderly with less diverse networks. Increased diversity in social networks was also associated with higher global cognitive function (coefficient=0.11, p<0.001) and higher physical function (coefficient=0.53, p<0.001).
Conclusions
Social networks are particularly important for older adults as they face the greatest threats to health and depend on network relationships, more than younger individuals, to meet their needs. Increasing diversity, and not just increasing size, of social networks may be essential for improving health and survival among older adults.
Introduction:
Precision medicine methodologies and approaches have advanced our understanding of the clinical presentation, development, progression, and management of Alzheimer's disease (AD) dementia. However, sex and gender have not yet been adequately integrated into many of these approaches.
Methods:
The Society for Women's Health Research Interdisciplinary Network on AD, comprised of an expert panel of scientists and clinicians, reviewed ongoing and published research related to sex and gender differences in AD.
Results:
The current review is a result of this Network's efforts and aims to: (1) highlight the current state-of-the-science in the AD field on sex and gender differences; (2) address knowledge gaps in assessing sex and gender differences; and (3) discuss 12 priority areas that merit further research.
Discussion:
The exclusion of sex and gender has impeded faster advancement in the detection, treatment, and care of AD across the clinical spectrum. Greater attention to these differences will improve outcomes for both sexes.
Cambridge Core - Research Methods In Politics - Egocentric Network Analysis - by Brea L. Perry
Objectives: The concept of cognitive reserve (CR) is defined as a moderator, which allows an individual to preserve cognition despite underlying brain pathology. There is no consensus of what potentially modifiable CR determinants are of greatest importance. The aim of this review was to identify life-course factors which protect older individuals from expressing cognitive decline despite the presence of brain pathology.
Method: A systematic review search was performed in MEDLINE (1946–06/09/13), EMBASE (1947–06/09/13), and PsycheInfo (1967–06/09/13). We included studies examining CR in the context of the four commonest subtypes of dementia, mild cognitive impairment or healthy aging. Studies which combined measurement of underlying dementia-related neuropathology, cognitive function, and factors providing CR in a single model were accepted. We performed a qualitative synthesis of the results.
Results: Thirty-four studies out of 9229 screened records met our inclusion criteria and were therefore quality assessed and data extracted. Variation in CR definition made comparison across studies difficult. One hundred and forty-four out of 156 models examined education and occupation: overall, 58% of eligible models classified education and 60% occupation as a CR determinant, with 12% and 44% of those, respectively, being of high quality. Within healthy population suitable to inform preventative interventions, there was consistent evidence for education having a protective effect on general cognition in the face of multiple brain burden measures, while occupation presented inconclusive results within cognitive groups.
Conclusions: Further research on modifiable determinants of CR beyond education/occupation including early-life factors and consensus on CR definition are warranted.
Cognitive Reserve and Brain Maintenance have traditionally been understood as complementary concepts: Brain Maintenance captures the processes underlying the structural preservation of the brain with age, and might be assessed relative to age-matched peers. Cognitive Reserve, on the other hand, refers to how cognitive processing can be performed regardless of how well brain structure has been maintained. Thus, Brain Maintenance concerns the “hardware,” whereas Cognitive Reserve concerns “software,” that is, brain functioning explained by factors beyond mere brain structure. We used structural brain data from 368 community-dwelling adults, age 20–80, to derive measures of Brain Maintenance and Cognitive Reserve. We found that Brain Maintenance and Cognitive were uncorrelated such that values on one measure did not imply anything about the other measure. Further, both measures were positively correlated with verbal intelligence and education, hinting at formative influences of the latter to both measures. We performed extensive split-half simulations to check our derived measures’ statistical robustness. Our approach enables the out-of-sample quantification of Brain Maintenance and Cognitive Reserve for single subjects on the basis of chronological age, neuropsychological performance and structural brain measures. Future work will investigate the prognostic power of these measures with regard to future cognitive status.
This is a review of argument and evidence on the connection between social networks and social capital. My summary points are three: (1) Research and theory will better cumulate across studies if we focus on the network mechanisms responsible for social capital effects rather than trying to integrate across metaphors of social capital loosely tied to distant empirical indicators. (2) There is an impressive diversity of empirical evidence showing that social capital is more a function of brokerage across structural holes than closure within a network, but there are contingency factors. (3) The two leading network mechanisms can be brought together in a productive way within a more general model of social capital. Structural holes are the source of value added, but network closure can be essential to realizing the value buried in the holes.
The associations between proxy measures of cognitive reserve (CR) and cognition vary across studies and cognitive domains. This meta-analysis aimed to assess the relationship between CR and cognition in multiple domains (memory, executive function, visuospatial ability, and language). CR was considered in terms of three key proxy measures - educational level, occupational status, and engagement in cognitively stimulating activities - individually and in combination. One-hundred and thirty-five studies representing 128,328 participants were included. Of these, 109 used a measure of education, 19 used a measure of occupation, 31 used a measure of participation in cognitively stimulating activities, and 6 used a combination of these. All three proxy measures had a modest positive association with cognition; occupational status and cognitive activities showed the most variation across cognitive domains. This supports the view that the commonly used proxy measures of CR share an underlying process but that each additionally provides a unique contribution to CR.
This is a review of argument and evidence on the connection between social networks and social capital. My summary points are three: (1) Research and theory will better cumulate across studies if we focus an the network mechanisms responsible for social capital effects rather than trying to integrate across metaphors of social capital loosely tied to distant empirical indicators. (2) There is an impressive diversity of empirical evidence showing that social capital is more a function of brokerage across structural holes than closure within a network, bur there are contingency factors. (3) The two leading network mechanisms can be brought together in a productive way within a more general model of social capital. Structural holes are the source of value added, but network closure can be essential to realizing the value buried in the holes.
Objective:
The pathologic indices of Alzheimer disease, cerebrovascular disease, and Lewy body disease accumulate in the brains of older persons with and without dementia, but the extent to which they account for late life cognitive decline remains unknown. We tested the hypothesis that these pathologic indices account for the majority of late life cognitive decline.
Methods:
A total of 856 deceased participants from 2 longitudinal clinical-pathologic studies, Rush Memory and Aging Project and Religious Orders Study, completed a mean of 7.5 annual evaluations, including 17 cognitive tests. Neuropathologic examinations provided quantitative measures of global Alzheimer pathology, amyloid load, tangle density, macroscopic infarcts, microinfarcts, and neocortical Lewy bodies. Random coefficient models were used to examine the linear relation of pathologic indices with global cognitive decline. In subsequent analyses, random change point models were used to examine the relation of the pathologic indices with the onset of terminal decline and rates of preterminal and terminal decline (ie, nonlinear decline).
Results:
Cognition declined a mean of about 0.11 U per year (estimate = -0.109, standard error [SE] = 0.004, p < 0.001), with significant individual differences in rates of decline; the variance estimate for the individual slopes was 0.013 (SE = 0.112, p < 0.001). In separate analyses, global Alzheimer pathology, amyloid, tangles, macroscopic infarcts, and neocortical Lewy bodies were associated with faster rates of decline and explained 22%, 6%, 34%, 2%, and 8% of the variation in decline, respectively. When analyzed simultaneously, the pathologic indices accounted for a total of 41% of the variation in decline, and the majority remained unexplained. Furthermore, in random change point models examining the influence of the pathologic indices on the onset of terminal decline and the preterminal and terminal components of the cognitive trajectory, the common pathologic indices accounted for less than a third of the variation in the onset of terminal decline and rates of preterminal and terminal decline.
Interpretation:
The pathologic indices of the common causes of dementia are important determinants of cognitive decline in old age and account for a large proportion of the variation in late life cognitive decline. Surprisingly, however, much of the variation in cognitive decline remains unexplained, suggesting that other important determinants of cognitive decline remain to be identified. Identification of the mechanisms that contribute to the large unexplained proportion of cognitive decline is urgently needed to prevent late life cognitive decline.
Objective:
To examine the hypothesis that diverse ties to friends, family, work, and community are associated with increased host resistance to infection.
Design:
After reporting the extent of participation in 12 types of social ties (eg, spouse, parent, friend, workmate, member of social group), subjects were given nasal drops containing 1 of 2 rhinoviruses and monitored for the development of a common cold.
Setting:
Quarantine.
Participants:
A total of 276 healthy volunteers, aged 18 to 55 years, neither seropositive for human immunodeficiency virus nor pregnant.
Outcome measures:
Colds (illness in the presence of a verified infection), mucus production, mucociliary clearance function, and amount of viral replication.
Results:
In response to both viruses, those with more types of social ties were less susceptible to common colds, produced less mucus, were more effective in ciliary clearance of their nasal passages, and shed less virus. These relationships were unaltered by statistical controls for prechallenge virus-specific antibody, virus type, age, sex, season, body mass index, education, and race. Susceptibility to colds decreased in a dose-response manner with increased diversity of the social network. There was an adjusted relative risk of 4.2 comparing persons with fewest (1 to 3) to those with most (6 or more) types of social ties. Although smoking, poor sleep quality, alcohol abstinence, low dietary intake of vitamin C, elevated catecholamine levels, and being introverted were all associated with greater susceptibility to colds, they could only partially account for the relation between social network diversity and incidence of colds.
Conclusions:
More diverse social networks were associated with greater resistance to upper respiratory illness.
Background:
Cognitive lifestyle may be an important modifiable risk factor for dementia but has not yet been comprehensively studied in healthy elderly.
Objective:
To examine gender- and lifespan-related differences in cognitive lifestyle in a population-based cohort.
Methods:
872 individuals from the second wave of the Sydney Memory and Ageing Study (MAS) cohort were invited to complete the Lifetime of Experiences Questionnaire (LEQ), a validated measure of cognitive lifestyle. Of 555 questionnaires returned (64%), 253 were excluded due to prior diagnosis of mild cognitive impairment, leaving n = 302 cognitively-intact elders (mean age 80.1 years, ±SD 4.7, 40.1% men).
Results:
Total LEQ was significantly higher in men (97.9 ± 20.0) than women (90.0 ± 24.5), resulting mainly from midlife LEQ differences. Men were more likely to have worked in managerial or professional jobs (73.8% versus 39.5% women), and twice as likely to have supervised large groups of workers. In late life, women were significantly more likely to be living alone (68.1% versus 25.4% men), but otherwise significantly more engaged in specific cognitive activities, including reading novels (72.3% versus 52.0% men) and incorporating volunteer work (31.9% versus 19.7% men) and socializing (59.0% versus 37.0% men) into their typical day. Over the adult lifespan, it was more common for men and women to transition between LEQ tertiles than remain the same.
Conclusions:
Cognitive lifestyle changes over the adult lifespan and exhibits a range of gender-based differences. While older women are more likely to be living alone they generally lead a more active current cognitive lifestyle.
Objective
This study aims to evaluate the impact of social isolation and loneliness, individually and simultaneously, on cognitive function in older adults during a 4-year period, using data from the English Longitudinal Study of Ageing, and to evaluate if these associations are moderated by educational level.Methods
Data on social isolation, loneliness, and cognitive function (verbal fluency, immediate recall, and delayed recall) were obtained at baseline. Follow-up measures on cognitive function were obtained 4 years later for 6034 participants (mean age at baseline = 65.6 years). Regression analyses were used to evaluate the association between baseline isolation, loneliness, and cognitive function at follow-up. Interactions between social isolation, loneliness, and educational level were also evaluated.ResultsBaseline isolation was significantly associated with decreases in all cognitive function measures at follow-up (β = -.05 to -.03, p < .001), independently of baseline scores, whereas loneliness was associated with poorer immediate recall (β = -.05, p < .001) and delayed recall (β = -.03, p = .02). There was a significant interaction between educational level and both isolation (p = .02) and loneliness (p = .01) for delayed recall, such that isolation and loneliness were associated with poorer recall only among those with low levels of education.Conclusions
Loneliness and isolation are associated with poorer cognitive function among older adults. Interventions to foster social connections may be particularly beneficial for individuals with low levels of education.
A Monte Carlo simulation examined the performance of 4 missing data methods in structural equation models: full information maximum likelihood (FIML), listwise deletion, pairwise deletion, and similar response pattern imputation. The effects of 3 independent variables were examined (factor loading magnitude, sample size, and missing data rate) on 4 outcome measures: convergence failures, parameter estimate bias, parameter estimate efficiency, and model goodness of fit. Results indicated that FIML estimation was superior across all conditions of the design. Under ignorable missing data conditions (missing completely at random and missing at random), FIML estimates were unbiased and more efficient than the other methods. In addition, FIML yielded the lowest proportion of convergence failures and provided near-optimal Type 1 error rates across both simulations.
Analysis of Ordinal Categorical Data Alan Agresti Statistical Science Now has its first coordinated manual of methods for analyzing ordered categorical data. This book discusses specialized models that, unlike standard methods underlying nominal categorical data, efficiently use the information on ordering. It begins with an introduction to basic descriptive and inferential methods for categorical data, and then gives thorough coverage of the most current developments, such as loglinear and logit models for ordinal data. Special emphasis is placed on interpretation and application of methods and contains an integrated comparison of the available strategies for analyzing ordinal data. This is a case study work with illuminating examples taken from across the wide spectrum of ordinal categorical applications. 1984 (0 471-89055-3) 287 pp. Regression Diagnostics Identifying Influential Data and Sources of Collinearity David A. Belsley, Edwin Kuh and Roy E. Welsch This book provides the practicing statistician and econometrician with new tools for assessing the quality and reliability of regression estimates. Diagnostic techniques are developed that aid in the systematic location of data points that are either unusual or inordinately influential; measure the presence and intensity of collinear relations among the regression data and help to identify the variables involved in each; and pinpoint the estimated coefficients that are potentially most adversely affected. The primary emphasis of these contributions is on diagnostics, but suggestions for remedial action are given and illustrated. 1980 (0 471-05856-4) 292 pp. Applied Regression Analysis Second Edition Norman Draper and Harry Smith Featuring a significant expansion of material reflecting recent advances, here is a complete and up-to-date introduction to the fundamentals of regression analysis, focusing on understanding the latest concepts and applications of these methods. The authors thoroughly explore the fitting and checking of both linear and nonlinear regression models, using small or large data sets and pocket or high-speed computing equipment. Features added to this Second Edition include the practical implications of linear regression; the Durbin-Watson test for serial correlation; families of transformations; inverse, ridge, latent root and robust regression; and nonlinear growth models. Includes many new exercises and worked examples.
Over the past 30 years investigators have called repeatedly for research on the mechanisms through which social relationships and social support improve physical and psychological well-being, both directly and as stress buffers. I describe seven possible mechanisms: social influence/social comparison, social control, role-based purpose and meaning (mattering), self-esteem, sense of control, belonging and companionship, and perceived support availability. Stress-buffering processes also involve these mechanisms. I argue that there are two broad types of support, emotional sustenance and active coping assistance, and two broad categories of supporters, significant others and experientially similar others, who specialize in supplying different types of support to distressed individuals. Emotionally sustaining behaviors and instrumental aid from significant others and empathy, active coping assistance, and role modeling from similar others should be most efficacious in alleviating the physical and emotional impacts of stressors.
Older people engage in social interaction less frequently than their younger counterparts. As I mentioned at the start, the change has been interpreted in largely negative terms. Yet when asked about their social relationships, older people describe them as satisfying, supportive, and fulfilling. Marriages are less negative and more positive. Close relationships with siblings are renewed, and relationships with children are better than ever before. Even though older people interact with others less frequently than younger people do, old age is not a time of misery, rigidity, or melancholy. Rather than present a paradox, I argue here that decreasing rates of contact reflect a reorganization of the goal hierarchies that underlie motivation for social contact and lead to greater selectivity in social partners. This reorganization does not occur haphazardly. Self-definition, information seeking, and emotion regulation are ranked differently depending not only on past experiences, but on place in the life cycle and concomitant expectations about the future. I contend that the emphasis on emotion in old age results from a recognition of the finality of life. In most people's lives this does not appear suddenly in old age but occurs gradually across adulthood. At times, however, life events conspire to bring about endings more quickly. Whether as benign as a geographical relocation or as sinister as a fatal disease, endings heighten the salience of surrounding emotions. When each interaction with a grandchild or good-bye kiss to a spouse may be the last, a sense of poignancy may permeate even the most casual everyday experiences. When the regulation of emotion assumes greatest priority among social motives, social partners are carefully chosen. The most likely choices will be long-term friends and loved ones, because they are most likely to provide positive emotional experiences and affirm the self. Information seeking will motivate some social behavior, but for reasons discussed previously, this will also require judicious choices of social partners. Narrowing the range of social partners allows people to conserve physical and cognitive resources, freeing time and energy for selected social relationships. As such, SST is highly consistent with the selective optimization with compensation model of successful aging formulated by P. Baltes and M. Baltes (1990) described above. SST is meant to describe and explain the underlying mechanisms for age-related changes in social behavior. It is not intended to be prescriptive.(ABSTRACT TRUNCATED AT 400 WORDS)
Dementia of the Alzheimer type (DAT) is accompanied by disruption in glucose regulation and utilization that may contribute to its characteristic memory impairment. Increasing glucose availability by raising plasma glucose improves memory in patients with DAT. Such memory improvement is associated with a secondary elevation in plasma insulin levels, raising the question of whether improvement is due to changes in insulin levels, independent of hyperglycemia. Distributions of insulin receptors in the hippocampus and insulin-mediated increases in glucose utilization in entorhinal cortex provide potential mechanisms for such improvement. We show that raising plasma insulin through intravenous infusion while keeping plasma glucose at a fasting baseline level produces striking memory enhancement for patients with DAT. Previous findings of hyperglycemic memory enhancement were also replicated. Patients with DAT also showed abnormal plasma levels of glucoregulatory hormones and metabolites at baseline and during metabolic manipulations. Our findings suggest that neuroendocrine factors play an important role in the pathophysiology of DAT.
To examine the relation of social resources and cognitive decline in older adults.
Data are from the Chicago Health and Aging Project, an epidemiologic study of risk factors for Alzheimer disease (AD) and other common conditions in a geographically defined population of older persons. The sample consisted of 6,102 non-Hispanic African Americans (61.2%) and whites, aged > or = 65, who underwent up to three interviews during an average of 5.3 years of follow-up. Each interview included administration of four cognitive function tests from which a composite measure of cognition was formed. Social networks were based on the number of children, relatives, and friends seen at least once a month. Social engagement was measured with four items related to social and productive activity.
Higher number of social networks and level of social engagement were positively correlated with initial level of cognitive function (networks estimate = 0.003, engagement estimate = 0.060, both p < 0.001). Both resources were also associated with a reduced rate of cognitive decline. A high (90th percentile) number of networks reduced the rate of decline by 39% compared to a low level (10th percentile), and high social engagement reduced decline by 91%. These relations remained after controlling for socioeconomic status, cognitive activity, physical activity, depressive symptoms, and chronic medical conditions.
Greater social resources, as defined by social networks and social engagement, are associated with reduced cognitive decline in old age.
To develop a 10-minute cognitive screening tool (Montreal Cognitive Assessment, MoCA) to assist first-line physicians in detection of mild cognitive impairment (MCI), a clinical state that often progresses to dementia.
Validation study.
A community clinic and an academic center.
Ninety-four patients meeting MCI clinical criteria supported by psychometric measures, 93 patients with mild Alzheimer's disease (AD) (Mini-Mental State Examination (MMSE) score > or =17), and 90 healthy elderly controls (NC).
The MoCA and MMSE were administered to all participants, and sensitivity and specificity of both measures were assessed for detection of MCI and mild AD.
Using a cutoff score 26, the MMSE had a sensitivity of 18% to detect MCI, whereas the MoCA detected 90% of MCI subjects. In the mild AD group, the MMSE had a sensitivity of 78%, whereas the MoCA detected 100%. Specificity was excellent for both MMSE and MoCA (100% and 87%, respectively).
MCI as an entity is evolving and somewhat controversial. The MoCA is a brief cognitive screening tool with high sensitivity and specificity for detecting MCI as currently conceptualized in patients performing in the normal range on the MMSE.
While most patients with mild cognitive impairment (MCI) transition to Alzheimer disease (AD), others develop non-AD dementia, remain in the MCI state, or improve.
To test the following hypotheses: smaller hippocampal volumes predict conversion of MCI to AD, whereas larger hippocampal volumes predict cognitive stability and/or improvement; and patients with MCI who convert to AD have greater atrophy in the CA1 hippocampal subfield and subiculum.
Prospective longitudinal cohort study.
University of California-Los Angeles Alzheimer's Disease Research Center.
We followed up 20 MCI subjects clinically and neuropsychologically for 3 years.
Baseline regional hippocampal atrophy was analyzed with region-of-interest and 3-dimensional hippocampal mapping techniques.
During the 3-year study, 6 patients developed AD (MCI-c), 7 remained stable (MCI-nc), and 7 improved (MCI-i). Patients with MCI-c had 9% smaller left and 13% smaller right mean hippocampal volumes compared with MCI-nc patients. Radial atrophy maps showed greater atrophy of the CA1 subregion in MCI-c. Patients with MCI-c had significantly smaller hippocampi than MCI-i patients (left, 24%; right, 27%). Volumetric analyses showed a trend for greater hippocampal atrophy in MCI-nc relative to MCI-i patients (eg, 16% volume loss). After permutation tests corrected for multiple comparison, the atrophy maps showed a significant difference on the right. Subicular differences were seen between MCI-c and MCI-i patients, and MCI-nc and MCI-i patients. Multiple linear regression analysis confirmed the group effect to be highly significant and independent of age, hemisphere, and Mini-Mental State Examination scores at baseline.
Smaller hippocampi and specifically CA1 and subicular involvement are associated with increased risk for conversion from MCI to AD. Patients with MCI-i tend to have larger hippocampal volumes and relative preservation of both the subiculum and CA1.
this paper was supported by the Institute Europen d'Administration d'Affaires (INSEAD) and the University of Chicago Graduate School of Business. Portions of the material were presented in 1998 at a "Social Networks and Social Capital" conference organized by Nan Lin and Karen Cook at Duke University, and a "Economic and Organizational Sociology" conference organized by Mauro Guilln and Douglas Massey at the University of Pennsylvania, in 1999 at a "Local Standards and Global Standards in the Age of Multiculturalism" conference organized by Noriyoshi Shiraishi and Yuki Yasuda at Rikkyo University, and in 2000 at the annual Organization Science Winter Conference, Michigan State University, and the annual Sunbelt Social Network Conference. The text has been improved in response to comments from Ranu Capron, Joseph Galaskiewicz, Bruce Kogut, Edward Laumann, Michael Moore, Joel Podolny, William Starbuck, Robert Sutton, Brian Uzzi, and Yuki Yasuda. NOTES For two reasons, focusing on managers probably means more evidence of social capital. First, Carroll and Teo (1996) use survey network data on a probability sample of Americans to show that manager networks (relative to nonmanagers) involve more participation in voluntary associations, more core discussion contacts, a larger proportion of contacts who are colleagues or co-workers, and more contacts who are total strangers to one another. Second, managers have more work autonomy than nonmanagers (Kohn and Schooler, 1983), and social capital is more of an advantage for people who have more autonomy (Burt, 1997a). More evidence of social capital makes professionals and managers a productive research site for studying social capital, but warrants a caution against generalizing to other populations