Karra Danyelle Harrington

• PhD
• PostDoc Position at Pennsylvania State University

Objective Remote assessment for cognitive screening and monitoring in the elderly has many potential advantages, including improved convenience/access and ease of repeat testing. As remote testing becomes more feasible and common, it is important to examine what factors might influence performance and adherence with these new methods. Personal beli...

From the perspective of traditional assessment approaches, variation in cognitive performance due to participant factors (e.g. mood, fatigue) are treated as part of measurement error. This talk will discuss how high-frequency assessment methods, such as ecological momentary assessment (EMA), can be leveraged to capture meaningful signal from variat...

Objective Intraindividual variability (IIV) is defined as fluctuations in an individual’s cognitive performance over time1. IIV has been identified as a marker of neurobiological disturbance making it a useful method for detecting changes in cognition among cognitively healthy individuals as well as those with prodromal syndromes2. IIV on laborator...

With an aging population, understanding cognitive aging is essential for developing interventions to support independence and well-being. Additionally, there is a need for sensitive measures that can differentiate subtle cognitive decline related to neurodegenerative disease from age-related changes. In particular, Alzheimer’s Disease and Related D...

Objective Routine cognitive screening in the elderly may facilitate earlier diagnosis of neurodegenerative diseases and access to care and resources for patients and families. However, despite growing rates of Alzheimer's and related disorders (ADRD), the availability and implementation of cognitive screening for older adults in the US remains quit...

INTRODUCTION We evaluated the accuracy of remote and in‐person digital tests to distinguish between older adults with and without AD pathological change and used the Montreal Cognitive Assessment (MoCA) as a comparison test. METHODS Participants were 69 cognitively normal older adults with known beta‐amyloid (Aβ) PET status. Participants completed...

DNA methylation-derived epigenetic clocks offer the opportunity to examine aspects of age acceleration (ie, the difference between an individual’s biological age and chronological age), which vary among individuals and may better account for age-related changes in cognitive function than chronological age. Leveraging existing ambulatory cognitive a...

Background Early life adversity and psychiatric disorders are associated with earlier declines in neurocognitive abilities during adulthood. These declines may be preceded by changes in biological aging, specifically epigenetic age acceleration, providing an opportunity to uncover genome-wide biomarkers that identify individuals most likely to bene...

Objectives: Loneliness in later life increases the risk for adverse health outcomes; however, less is known about how loneliness is maintained. Anxiety may play an important role in maintaining loneliness, but little is known about how this connection plays out over time in daily life. This study thus focused on the within-person associations betw...

DNA methylation-derived epigenetic clocks offer the opportunity to examine aspects of age acceleration (i.e., the difference between an individual’s biological age and chronological age), which vary among individuals and may better account for age-related changes in cognitive function than chronological age. Leveraging existing ambulatory cognitive...

Background Loneliness has been highlighted as a risk factor for dementia. However, the nature of the relationship between loneliness and cognitive function prior to onset of dementia is unclear. Objective The aim of this systematic review and meta-analysis was to examine the relationship between loneliness and cognitive function in samples screene...

Loneliness has consistently been associated with dementia risk. An important precursor to dementia is cognitive decline, which can begin decades prior to clinical diagnosis of dementia. Therefore, understanding about the relationship between loneliness and cognitive function in healthy older adults may inform our understanding of how loneliness con...

Repetitive negative thinking (RNT) has been associated with faster cognitive decline and accumulation of Alzheimer’s disease pathology in otherwise healthy older adults. According to the cognitive debt hypothesis, RNT functions as a psychological mechanism that depletes cognitive resources and increases vulnerability for dementia. The aim of this p...

Loneliness is associated with increased dementia risk, and greater amyloid‐β (Aβ) and tau accumulation in cognitively normal older adults. However, the potential for loneliness to influence cognitive dysfunction during the preclinical disease stage has not yet been examined. Subjective cognitive complaints are an early indicator of cognitive dysfun...

Objectives: Deviations from normative trajectories of receptive language abilities following early life adversity (ELA) may indicate an elevated risk for advanced cognitive aging and related morbidities. Accelerated epigenetic aging at midlife may further identify those at greatest risk for advanced cognitive aging following ELA. We examined wheth...

Monitoring early changes in cognitive performance is useful for studying cognitive aging as well as for detecting early markers of neurodegenerative diseases. Repeated evaluation of cognition via a measurement burst design can accomplish this goal. In such design participants complete brief evaluations of cognition, multiple times per day for sever...

Objectives: Loneliness has been linked to poor mental and physical health outcomes in later life. Little is known about how daily social interactions relate to older adults' everyday experiences of loneliness. This study examined the dynamic associations between social interactions and the momentary feelings of loneliness in older adults' daily li...

Introduction: The early detection of cognitive impairment is one of the most important challenges in Alzheimer's disease (AD) research. The use of brief, short-term repeated test sessions via mobile app has demonstrated similar or better reliability and validity compared to standard in-clinic assessments in adult samples. The present study examine...

In March 2020, residents of the Bronx, New York experienced one of the first significant community COVID-19 outbreaks in the United States. Focusing on intensive longitudinal data from 78 Bronx-based older adults, we used a multi-method approach to (1) examine 2019 to early pandemic (February-June 2020) changes in momentary psychological well-being...

Purpose This paper aims to provide an overview of a peer-supported writing and wellbeing pilot program for higher degree by research (HDR) students in Australia. It proposes a six-month program is a beneficial service to HDR students that improves not only their productivity and writing confidence but assists with their perceived mental wellbeing a...

Loneliness has been linked to poor mental and physical health outcomes. Past research suggests that inflammation is a potential pathway linking loneliness and health, but little is known about how loneliness assessed in daily life links with inflammation, or about linkages between loneliness and inflammation among older adults specifically. As part...

This study focused on investigating the short-term effect of loneliness on older adults’ cognitive performances in daily life. Loneliness is suggested as a risk factor for cognitive health, but results in previous studies are inconsistent due to the lack of valid measures and limited research design. The attention-depletion hypothesis highlights th...

Loneliness is prevalent among older adults and is associated with increased risks for morbidity and mortality. This study examined what types of social interactions could reduce loneliness for older adults and who would benefit the most from social interactions. We used data from 312 community-dwelling older adults (aged 70 to 90 years) who complet...

Self-reported cognitive difficulties are common in older adults and may be an early indicator of future cognitive decline or dementia. In past retrospective reports, cognitive difficulties have been linked with differences in social engagement or social relationships among older adults. However, little is known about how self-reported cognitive dif...

Objectives: Physical activity (PA) is beneficial for older adults' cognition. There is limited research investigating perspectives of support persons (SPs) of next-of-kins (NOKs) with cognitive impairment. This exploratory study aimed to investigate perspectives of SPs of older adults with Alzheimer's Dementia (AD) or Mild Cognitive Impairment (MCI...

This paper presents the co-design process of a digital tool that may prevent or alleviate feelings of loneliness in older adults. Six workshops were conducted with older adults (n=34) aged between 65-80 years old to investigate the role of technology in maintaining and establishing meaningful relationships. Participants’ contributions throughout th...

Neurodegenerative disease is highly prevalent among older adults and, if undetected, may obscure estimates of cognitive change among aging samples. Our aim in this study was to determine the nature and magnitude of cognitive change in the absence of common neuropathologic markers of neurodegenerative disease. Cognitively normal older adults (ages 6...

Loneliness is an important health issue facing older people due to its association with poor quality of life and poor health outcomes. This paper aimed to clarify key issues around loneliness among older adults and draw attention to innovative programs and the translation of emerging research into practice. Loneliness is a mismatch between a person...

Older adults may be particularly vulnerable to experiencing loneliness as a result of stay-at-home and social distancing orders during the COVID-19 pandemic. This study evaluated change in loneliness following the COVID-19 outbreak, using a longitudinal design and a validated loneliness measure, in a well-characterized sample who are at heightened...

Loneliness is a risk factor for dementia, however it’s relationship with cognitive health during midlife is unclear. We evaluated whether loneliness was associated with profiles of objective and subjective memory in younger and middle-aged adults. Participants (aged 25 to 64 years) underwent an initial loneliness assessment, followed by 14-days of...

Loneliness has been investigated as a risk factor for cognitive health, but results were inconsistent. This study used three measurement bursts of ambulatory cognitive assessment to determine whether loneliness affects longitudinal changes in cognitive functioning in daily life. At each burst, participants performed cognitive assessment five times...

Understanding age-related change in cognition and identification of pathological changes requires sensitive and valid measurement of cognitive performance across time. Technological advances, such as ambulatory assessment of cognition using smartphones, have enabled intensive longitudinal methods where data is collected with many measurements over...

Background University students are vulnerable to poor mental health, psychological distress, and loneliness relative to nonuniversity student peers. However, the rate of seeking mental health treatment among university students is low. Web-based psychological interventions may provide an opportunity for supporting vulnerable university students who...

BACKGROUND University students are vulnerable to poor mental health, psychological distress, and loneliness relative to nonuniversity student peers. However, the rate of seeking mental health treatment among university students is low. Web-based psychological interventions may provide an opportunity for supporting vulnerable university students who...

Introduction: Superior cognitive performance in older adults may reflect underlying resistance to age-associated neurodegeneration. While elevated amyloid β (Aβ) deposition (Aβ+) has been associated with increased cortical atrophy, it remains unknown whether "SuperAgers" may be protected from Aβ-associated neurodegeneration. Methods: Neuropsycho...

Introduction: Preclinical Alzheimer’s disease (AD) is characterized by amyloid-related cognitive decline. Reduction in this decline is used to determine the efficacy of drug therapies designed to forestall the disease in preclinical AD clinical trials, measured by a Preclinical Alzheimer’s Cognitive Composite (PACC). Most studies estimate rates of...

Objective: To prospectively examine 8-year risk of clinical disease progression to mild cognitive impairment (MCI)/dementia in older adults ≥60 with superior episodic memory (SuperAgers) compared to those cognitively normal for their age (CNFA). Additionally, to determine the extent to which SuperAgers were resilient to the negative effects of ele...

Background It is possible that estimates of normal age-related decline in intellectual function have been biased negatively by undetected preclinical Alzheimer's disease (AD). This prospective study aimed to determine the nature and magnitude of changes in crystallized and fluid intelligence, as well as their relationship to one another, in normal...

Background Preclinical Alzheimer’s disease (AD) is defined by cerebral amyloid-β positivity (Aβ+) in cognitively normal (CN) older adults. Objective To estimate the risk of progression to the symptomatic stages of AD due to PET Aβ+ and the extent that progression was influenced by other demographic, genetic, and clinical characteristics in a large...

Doctoral students can use writing meet-ups to overcome isolation and depression — and boost their motivation, says Karra Harrington. Doctoral students can use writing meet-ups to overcome isolation and depression — and boost their motivation.

Cognitive decline is considered an inevitable consequence of aging; however, estimates of cognitive aging may be influenced negatively by undetected preclinical Alzheimer's disease (AD). This study aimed to determine the extent to which estimates of cognitive aging were biased by preclinical AD. Cognitively normal older adults (n = 494) with amyloi...

Background: Relationships between depression and Alzheimer's disease (AD) may become clearer if studied in preclinical AD where dementia is not present. Method: The aim of this study was to evaluate prospectively, relationships between brain amyloid-β (Aβ), depressive symptoms and screen positive depression in cognitively normal (CN) older adult...

Alzheimer's Disease (AD) is the most common form of dementia, characterised by extracellular amyloid deposition as plaques and intracellular neurofibrillary tangles of tau protein. As no current clinical test can diagnose individuals at risk of developing AD, the aim of this project is to evaluate a blood-based biomarker panel to identify individua...

Introduction High levels of amyloid β (Aβ) are associated with cognitive decline in cognitively normal (CN) older adults. This study investigated the nature of cognitive decline in healthy individuals who did not progress to mild cognitive impairment or dementia. Method Cognition was measured over 72 months and compared between low (Aβ−) and high...

Evidence suggests that a diet low in carbohydrates can impact on cognitive performance among those with Alzheimer’s disease (AD). However, there is a lack of data assessing this relationship among cognitively normal (CN) older adults at increased future risk of developing AD due to carriage of the apolipoprotein E (APOE) ɛ4 allele. We assessed the...

Background: In cognitively normal (CN) older adults, carriage of the apolipoprotein E (APOE) ɛ4 allele is associated with increased risk for dementia of the Alzheimer type (AD-dementia). It is unclear whether this occurs solely through APOE ɛ4 increasing amyloid-β (Aβ) accumulation or through processes independent of Aβ. Objective: To determine the...

Objective: The extent to which increasing age is associated with impairment in cognitive function, termed cognitive aging, may have been overestimated in prior studies. The inclusion of individuals with severe or uncontrolled systemic medical illness or prodromal neurodegenerative disease in normal aging samples is likely to bias estimates toward...

Alzheimer’s disease (AD) is a degenerative brain disorder and is the most common form of dementia. Minimally invasive approaches are required that combine biomarkers to identify individuals who are at risk of developing mild cognitive impairment (MCI) and AD, to appropriately target clinical trials for therapeutic discovery as well as lifestyle str...

Objective: Several studies have reported that non-demented older adults with clinical depression show changes in amyloid-β (Aβ) levels in blood, cerebrospinal fluid and on neuroimaging that are consistent with those observed in patients with Alzheimer's disease. These findings suggest that Aβ may be one of the mechanisms underlying the relation be...

Alzheimer disease (AD) is now known to have a long preclinical phase in which pathophysiologic processes develop many years, even decades, before the onset of clinical symptoms. Although the presence of abnormal levels of amyloid-β (Aβ) is associated with higher rates of progression to clinically classified mild cognitive impairment or dementia, li...

Memory changes in preclinical Alzheimer's disease (AD) are often characterized by heterogenous trajectories. However, data regarding the nature and determinants of predominant trajectories of memory changes in preclinical AD are lacking. We analyzed data from 333 cognitively healthy older adults who participated in a multicenter prospective cohort...

The apolipoprotein E (APOE) ɛ4 allele and high levels of beta-amyloid (Aβ) are associated with episodic memory decline and risk for Alzheimer's disease. However, there is debate about independent or interactive effects of ɛ4 on Aβ-related memory decline in healthy older adults. Healthy older adults with high Aβ burden (n = 84) enrolled in Australia...

We investigated the extent to which decline in memory and working memory in beta-amyloid (Aβ) positive non-demented individuals was related to hippocampal atrophy and Aβ accumulation over 36 months. Cognitively normal older adults (CN) (n = 178) and adults with mild cognitive impairment (MCI) (n = 49) underwent positron emission tomography neuroima...

Depression has been shown to be a risk factor for Alzheimer's disease (AD), and in older adults may provide a marker for the beginning of the prodromal phase of AD. The purpose of this systematic review is to examine the relationship between amyloid-β (Aβ), a key biomarker of AD, and depression in older adults. The literature search was limited to...

Background High β-amyloid (Aβ) is associated with faster memory decline in healthy individuals and adults with mild cognitive impairment (MCI). However, longer prospective studies are required to determine if Aβ-related memory decline continues and whether it is associated with increased rate of disease progression. Methods Healthy controls (HCs;...

Accumulation of β-amyloid (Aβ) in the brain is associated with memory decline in healthy individuals as a prelude to Alzheimer’s disease (AD). Genetic factors may moderate this decline. We examined the role of apolipoprotein E (ε4 carrier[ε4+], ε4 non-carrier[ε4−]) and brain-derived neurotrophic factor (BDNFVal/Val, BDNFMet) in the extent to which...

Background The detection of early Alzheimer's disease (AD) can rely on subjective and informant reports of cognitive impairment. However, relationships between subjective cognitive impairment, objectively measured cognitive function, and amyloid-β (Aβ) biomarkers remain unclear. Objective To determine the extent to which impairment or decline in s...

Methods: Participants include N¼168 patients ages 60-90 recruited from the Saint Louis University Geriatric Medicine and Geriatric Psychiatry outpatient clinics during summer 2013.The study sample included 61% females and 42% African Americans. Receiver operator characteristic (ROC) curves were calculated to determine the RCS sensitivity and specif...

The aim of this paper was to investigate the association of three well-recognised dietary patterns with cognitive change over a 3-year period. Five hundred and twenty-seven healthy participants from the Australian Imaging, Biomarkers and Lifestyle study of ageing completed the Cancer Council of Victoria food frequency questionnaire at baseline and...

Although beta-amyloid, anxiety and depression have been linked cross-sectionally to reduced memory function in healthy older adults without dementia, prospective data evaluating these associations are lacking. Using data from an observational cohort study of 178 healthy older adults without dementia followed for 3 years, we found that anxiety sympt...

High amyloid has been associated with substantial episodic memory decline over 18 and 36 months in healthy older adults and individuals with mild cognitive impairment. However, the nature and magnitude of amyloid-related memory and non-memory change from the preclinical to the clinical stages of Alzheimer's disease has not been evaluated over the s...

Background: To date evidence of the relationship between cognition and Aβ amyloid during the early stages of Alzheimer's Disease (AD) has been inconsistent. This study aimed to describe the nature and magnitude of the relationship between Aβ amyloid and cognitive performance of individuals without dementia. Methods: Composite cognitive measures...

Brain-derived neurotrophic factor (BDNF) Val66Met polymorphism has previously been implicated in Alzheimer's disease (AD)erelated cognitive impairment. We aimed to determine the relationship between BDNF Val66Met and beta-amyloid (Ab) on cognitive decline, hippocampal atrophy, and Ab accumulation over 36 months in 165 healthy adults enrolled in the...

Background: It has been proposed that only mild cognitive impairment (MCI) with high Aβ amyloid is indicative of incipient Alzheimer’s disease (AD), yet MCI with low Aβ amyloid may reflect other neurodegenerative processes. We aimed to determine the extent to which high Aβ amyloid influenced cognitive function in healthy older adults and adults wit...

Large prospective studies of Alzheimer's disease (AD) have sought to understand the pathological evolution of AD and factors that may influence the rate of disease progression. Estimates of rates of cognitive change are available for 12 or 24 months, but not for shorter time frames (e.g., 3 or 6 months). Most clinical drug trials seeking to reduce...

We aimed to characterize the nature and magnitude of cognitive decline in a group of healthy older adults with high and low levels of amyloid-β (Aβ) and who were APOE ε4 carriers and non-carriers. Healthy older adults underwent positron emission tomography neuroimaging for Aβ, APOE genotyping, and cognitive and clinical assessment as part of their...

We aimed to characterize the nature and magnitude of cognitive decline in a group of adults with amnestic mild cognitive impairment (aMCI) with high and low levels of amyloid-β (Aβ) in relation to healthy older adults with low Aβ levels. Healthy older adults and adults with aMCI enrolled in the Australian Imaging, Biomarker, and Lifestyle study, co...

Background: Only one study has investigated the relationship between cerebral β-amyloid (Aβ), apolipoprotein E (APOE) ε4 genotype, and cognition. Although significant relationships between cerebral Aβ and cognition were observed in ε4 carriers but not noncarriers, the magnitude of this relationship was not reported. Further, when demographic varia...

Objective: Although the APOE ε4 allele is associated with more rapid decline in memory in healthy older adults, the significance of elevated cerebral β-amyloid (Aβ) load for longitudinal changes in cognition is unclear. Methods: Healthy and cognitively normal older adults (n = 141; mean age 76 years) underwent PET neuroimaging for cerebral Aβ, A...

There is a need for culture neutral neuropsychological instruments. The International Shopping List Test (ISLT) is sensitive to memory impairment in Alzheimer's disease (AD) in different cultural groups, although its sensitivity to mild cognitive impairment (MCI) and ability to be given repeatedly at short retest intervals is unknown. Performance o...

The aim of this study was to validate the CogState Brief Battery, which assesses psychomotor, attentional, working memory, and visual learning functions, in healthy older people and in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD), enrolled in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study. In healthy old...

High levels of amyloid-β (Aβ) have been associated with greater rates of decline in episodic memory over 18 months in healthy older adults. Serial assessments over shorter time intervals may facilitate earlier detection of Aβ-related memory decline in healthy older adults. In forty-four healthy older adults enrolled in the Australian Imaging, Bioma...