Ronald Cohen

University of Florida, Gainesville, Florida, United States

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Publications (58)164.54 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Reduced physical activity (PA) may be one factor that contributes to cognitive decline and dementia in heart failure (HF). Yet, the longitudinal relationship between PA and cognition in HF is poorly understood due to limitations of past work, including single time assessments of PA. This is the first study to examine changes in objectively measured PA and cognition over time in HF. At baseline and 12-weeks, 57 HF patients completed psychosocial self-report measures, a neuropsychological battery, and wore an accelerometer for seven days. At baseline, HF patients spent an average of 597.83 (SD = 75.91) minutes per day sedentary. Steps per day declined from baseline to the 12-week follow-up; there was also a trend for declines in moderate-vigorous PA. Regression analyses controlling for sex, HF severity, and depressive symptoms showed that decreases in light (p = 0.08) and moderate-vigorous (p = 0.04) daily PA emerged as strong predictors of declines in attention/executive function over the 12-week period, but not memory or language. Reductions in daily PA predicted acute decline in attention/executive function in HF, but not memory or language. Modifications to daily PA may attenuate cognitive decline and prospective studies are needed to test this possibility. Copyright © 2014 Elsevier Inc. All rights reserved.
    Journal of cardiac failure. 01/2015;
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    ABSTRACT: Heart failure patients require assistance with instrumental activities of daily living in part because of the high rates of cognitive impairment in this population. Structural brain insult (eg, reduced gray matter volume) is theorized to underlie cognitive dysfunction in heart failure, although no study has examined the association among gray matter, cognition, and instrumental activities of daily living in heart failure. The aim of this study was to investigate the associations among gray matter volume, cognitive function, and functional ability in heart failure. A total of 81 heart failure patients completed a cognitive test battery and the Lawton-Brody self-report questionnaire to assess instrumental activities of daily living. Participants underwent magnetic resonance imaging to quantify total gray matter and subcortical gray matter volume. Impairments in instrumental activities of daily living were common in this sample of HF patients. Regression analyses controlling for demographic and medical confounders showed that smaller total gray matter volume predicted decreased scores on the instrumental activities of daily living composite, with specific associations noted for medication management and independence in driving. Interaction analyses showed that reduced total gray matter volume interacted with worse attention/executive function and memory to negatively impact instrumental activities of daily living. Smaller gray matter volume is associated with greater impairment in instrumental activities of daily living in persons with heart failure, possibly via cognitive dysfunction. Prospective studies are needed to clarify the utility of clinical correlates of gray matter volume (eg, cognitive dysfunction) in identifying heart failure patients at risk for functional decline and determine whether interventions that target improved brain and cognitive function can preserve functional independence in this high-risk population.
    The Journal of cardiovascular nursing 11/2014; · 1.81 Impact Factor
  • Journal of the American Geriatrics Society 11/2014; 62(11). · 4.22 Impact Factor
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    ABSTRACT: Introduction: Treatment nonadherence is common in heart failure (HF) and is associated with poor health outcomes in this population. Recent cross-sectional work in heart failure and past work in other medical populations suggest that cognitive function is a key determinant of a patient's ability to adhere to treatment recommendations. However, it is also possible that treatment adherence is an important modifier and predictor of cognitive function, though no study has examined this possibility, and we sought to do so in a sample of heart failure patients. Method: A total of 115 patients with heart failure self-reported adherence to treatment recommendations. The Modified Mini Mental State Examination (3MS), Trail Making Test Parts A and B, and the California Verbal Learning Test-II (CVLT-II) assessed cognitive function. These procedures were performed at baseline and a 12-month follow-up. Results: Global cognition and memory abilities improved over the 12-month period. Regression analyses controlling for baseline and medical and demographic factors showed that better baseline treatment adherence predicted improved 12-month performances on the 3MS and CVLT-II. Adherence to medication and diet regimens and smoking abstinence emerged as the most important contributors. Conclusions: Better treatment adherence predicted improved cognition one year later in HF. Prospective studies that utilize objective assessments of treatment adherence are needed to confirm our findings and examine whether improved treatment adherence preserves cognitive function in heart failure.
    Journal of Clinical and Experimental Neuropsychology 10/2014; · 2.16 Impact Factor
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    ABSTRACT: Objective: Bariatric surgery is associated with improved cognitive function, though the mechanisms are unclear. Elevated inflammation is common in obesity and associated with impaired cognition. Inflammation decreases after bariatric surgery, implicating it as a possible mechanism for cognitive improvement. The objective of this study was to examine whether reduced inflammation is a possible mechanism for post-operative cognitive improvement in bariatric surgery patients. Methods: Participants were 77 bariatric surgery patients who completed cognitive testing before surgery and one year post-surgery. Cognitive domains assessed were attention/executive function, language, and memory. High-sensitivity C-reactive protein (hs-CRP) was assessed at both time points. Results: Patients exhibited pre-operative cognitive impairment, though attention/ executive (M±SDbaseline= 53.57 ± 8.68 vs. M±SDfollow-up= 60.32 ± 8.19) and memory (M±SDbaseline= 44.96 ± 7.98 vs. M±SDfollow-up= 51.55 ± 8.25) improved one year post-surgery. CRP was elevated at baseline and fell into the normative range post-surgery (M±SDbaseline= 0.9 ± 0.7 vs. M±SDfollow-up= 0.2 ± 0.3 mg/dL). Pre-operative CRP was not associated with baseline cognitive function (β-values = -0.10 to 0.02) and changes in CRP also did not correspond to changes in cognition post-surgery (β-values = 0.02 to β = 0.11; ps >0.05 for all domains). A trend was detected for smaller improvements in memory among participants with elevated baseline CRP (>0.30 mg/dL) versus those with normal levels (Group x Time: p=0.083). Conclusions: Improvements in hs-CRP were not associated with post-operative cognitive benefits. Future studies are needed to explore other inflammatory markers and potential mechanisms of cognitive improvement after bariatric surgery, including improved glycemic control and neurohormone changes.
    Psychosomatic Medicine 10/2014; in press. · 4.09 Impact Factor
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    ABSTRACT: Obesity-associated cognitive impairments may be partially reversible through bariatric surgery. Depression, a prevalent comorbidity in bariatric surgery candidates, is linked with cognitive impairment and poorer surgical outcomes in other populations. No study has examined the effects of pre-operative depression on cognitive changes in bariatric surgery patients. Sixty-seven bariatric surgery patients completed a computerized cognitive test battery prior to surgery and 12 months post-operatively. The structured clinical interview for the DSM-IV Axis I disorders assessed major depressive disorder (MDD). Pre-surgery history of MDD was found in 47.8% of patients, but was not associated with greater baseline cognitive impairments. Repeated measures revealed improved cognitive abilities 12 months after surgery. Pre-surgery history of MDD did not influence post-operative cognitive function. Pre-operative history of MDD did not limit post-operative cognitive improvements. Larger studies with extended follow-ups are needed to clarify our findings and identify factors (e.g. older age) that may modify cognitive changes following surgery.
    Psychology Health and Medicine 09/2014; · 1.53 Impact Factor
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    ABSTRACT: Evidence suggests that both obesity and binge eating disorder (BED) may be associated with deficits in cognitive functioning. The purpose of this study was to examine whether a lifetime history of BED would be associated with changes in several domains of cognitive functioning (attention, executive function, language, and memory) following bariatric surgery. Participants were 68 bariatric surgery patients who completed a computerized battery of cognitive tests within 30 days prior to undergoing surgery and again at a 12-Month postoperative follow-up. Results revealed that on the whole, participants displayed improvements from baseline to follow-up in attention, executive function, and memory, even after controlling for diagnostic history of depression; no changes were observed for language. However, individuals with and without a history of BED did not differ in changes in body mass index or in the degree of improvement in cognitive functioning from baseline to follow-up. Such results suggest that a history of BED does not influence changes in cognitive functioning following bariatric surgery. Future research will be needed to further clarify the role of BED in predicting cognitive function over time.
    Journal of Psychiatric Research 08/2014; · 4.09 Impact Factor
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    ABSTRACT: Heart failure (HF) is a known risk factor for cognitive impairment. Cardiac rehabilitation (CR) may attenuate poor neurocognitive outcomes in HF via improved physical fitness--a significant promoter of cognitive function. However, no study has examined the possible acute and lasting benefits of CR on cognitive function in persons with HF.
    Acta cardiologica. 08/2014; 69(4):407-14.
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    ABSTRACT: The mechanisms for improved cognitive function post-bariatric surgery are not well understood. Markers of kidney and liver function (i.e., cystatin C and alkaline phosphatase (ALP)) are elevated in obese individuals and associated with poor neurocognitive outcomes in other samples. Bariatric surgery can improve cystatin C and ALP levels, but no study has examined whether such changes correspond to post-operative cognitive benefits.
    Journal of the Neurological Sciences 07/2014; · 2.26 Impact Factor
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    ABSTRACT: Cognitive impairment is common in heart failure. Obesity is a known risk factor for cognitive dysfunction in heart failure, though the mechanisms remain unclear. Obesity increases risk for conditions like hypertension and type 2 diabetes mellitus (T2DM) as well as poor fitness levels, and this may serve as one possible pathway accounting for association between obesity and cognitive dysfunction. We used structural equation modeling to test whether the combination of hypertension, T2DM, and reduced fitness mediate the association between obesity and cognitive dysfunction. Two hundred heart failure patients completed neuropsychological testing and a physical fitness assessment. Hypertension and T2DM were ascertained via self-report and medical records. Body mass index (BMI) was calculated. Forty-three percent of the sample was obese. Hypertension (70%) and T2DM (36%) were common, and fitness levels were reduced. The structural equation model with these factors as mediators between BMI and cognitive function demonstrated excellent fit (comparative fit index = 0.98; root mean-square error of approximations = 0.03). Higher BMI correlated with hypertension, T2DM, and poorer fitness. Each of these factors predicted worse cognition. Models that isolated medical comorbidities and physical fitness as the mediator were weaker than the full model. Increased risk for medical comorbidities and reduced fitness levels helped to explain the negative effects of obesity on cognitive dysfunction in heart failure. Prospective studies should confirm this pattern and examine how weight loss benefits cognitive function in heart failure.
    European Journal of Cardiovascular Nursing 05/2014; · 2.04 Impact Factor
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    ABSTRACT: Background Bariatric surgery is associated with cognitive benefits, but the nature of such gains may be variable across demographically and clinically diverse persons. Older adults achieve less weight loss and resolution of fewer medical comorbidities after surgery compared to younger patients, and are also at heightened risk for nutritional deficiencies. However, no study has examined the influence of age on cognitive improvements after bariatric surgery. Objective To determine the effects of age on cognitive function post-bariatric surgery. Setting Hospital. Methods 95 participants enrolled in the Longitudinal Assessment for Bariatric Surgery completed a computerized cognitive test battery prior to bariatric surgery and at 12-weeks, and 12-months post-operatively. Results Baseline cognitive impairments were common. Significant improvements were found in attention/executive function and memory abilities 12-weeks and 12-months after surgery. Age was not associated with baseline cognitive test performance. Separate multivariable regression analyses controlling for baseline attention/executive function and memory also showed that age was not a significant predictor of 12-week or 12-month performances in these domains (p > 0.05 for all). Conclusions The current study provides preliminary evidence suggesting that older age does not preclude post-bariatric surgery cognitive benefits. Prospective studies in more age diverse samples (i.e., up to 70 years) are needed to determine whether bariatric surgery can reduce risk of age-related neurological conditions like Alzheimer’s disease and stroke.
    Surgery for Obesity and Related Diseases 04/2014; · 4.94 Impact Factor
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    ABSTRACT: Objective Cognitive impairment in heart failure (HF) is believed to result from brain hypoperfusion subsequent to cardiac dysfunction. Physical inactivity is prevalent in HF and correlated with reduced cardiac and cognitive function. Yet, no longitudinal studies have examined the neurocognitive effects of physical inactivity in HF. The current study examined whether reduced physical activity increases risk for cognitive impairment and brain hypoperfusion over time in HF. Methods At baseline and 12-months later, 65 HF patients underwent neuropsychological testing, transcranial doppler ultrasonography, and were asked to wear an accelerometer for seven days. Results Lower baseline step count and less time spent in moderate free-living activity best predicted worse attention/executive function and decreased cerebral perfusion at the 12-month follow-up. Decreased baseline cerebral perfusion also emerged as a strong predictor of poorer 12-month attention/executive function. Conclusions Lower physical activity predicted worse cognition and cerebral perfusion 12-months later in HF. Physical inactivity in HF may contribute to cognitive impairment and exacerbate risk for conditions such as Alzheimer’s disease. Larger studies are needed to elucidate the mechanisms by which physical inactivity leads to cognitive dysfunction in HF, including clarification of the role of cerebral hypoperfusion.
    Journal of the neurological sciences 04/2014; · 2.32 Impact Factor
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    ABSTRACT: Abstract Cognitive impairment is common in severe obesity. Lack of physical activity is a likely contributor to impairment in this population, as many obese persons are inactive and physical activity has been positively and independently associated with cognitive function in healthy and medically-ill samples. This study investigated whether physical activity, measured by self-report of aerobic physical activity in 85 bariatric surgery candidates, was associated with cognitive function. A subset of 31 participants also completed objective activity monitoring. Steps/day and high-cadence minutes/week, representative of ambulatory moderate to vigorous physical activity (MVPA), were calculated. Approximately one quarter of participants self-reported at least 30 minutes/day of aerobic MVPA, at least 5 days per week. Median steps/day was 7949 (IQR = 4572) and median MVPA min/week was 105 (IQR = 123). Cognitive deficits were found in 32% of participants (29% memory, 10% executive function, 13% language, 10% attention). Controlling for demographic and medical factors, self-reported aerobic physical activity was weakly correlated with lower attention (r = -.21, p = .04) and executive function (r = -.27, p < .01) and both self-reported aerobic physical activity and objectively-determined MVPA min/week were negatively correlated with memory (r = -.20, p = .04; r = -.46; p = .02, respectively). No other correlations between physical activity measures and cognitive function were significant. Contrary to expectations, greater levels of physical activity were not associated with better cognitive functioning. Such findings encourage future studies to clarify the association among cognitive function and physical activity in obese persons.
    The International journal of neuroscience 02/2014; 124(12). · 1.53 Impact Factor
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    ABSTRACT: Objective: Nearly 6 million Americans have heart failure (HF), up to 80% of which exhibit cognitive deficits on testing. Physical inactivity is common in HF, yet little is known about the possible contribution of physical inactivity to cognitive dysfunction in this population. Method: Older adults with HF (N = 93; Mage = 68.5 years, 33.7% women) completed neuropsychological testing, as well as cardiac and physical activity assessment as part of a larger protocol. HF severity was measured via impedance cardiography. Physical activity was assessed via an Actigraph accelerometer and operationalized using daily step count and time engaged in moderate-vigorous activity (minutes/day). Results: Linear regression analyses controlling for sex, high blood pressure, diabetes, depressive symptomatology, and HF severity showed that greater physical activity (both step count and minutes spent in moderate-vigorous activity) was associated with better executive function/attention, processing speed, and scores on a screening measure of cognition. Conclusions: These findings indicate that physical activity is an independent predictor of cognitive function in persons with HF. Future work is needed to clarify the mechanisms by which physical activity benefits cognitive function in HF and determine whether interventions to promote physical activity can attenuate cognitive decline over time. (PsycINFO Database Record (c) 2014 APA, all rights reserved).
    Health Psychology 01/2014; · 3.95 Impact Factor
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    ABSTRACT: Poor sleep is common in heart failure (HF), though mechanisms of sleep difficulties are not well understood. Adverse brain changes among regions important for sleep have been demonstrated in patients with HF. Cerebral hypoperfusion, a correlate of sleep quality, is also prevalent in HF and a likely contributor to white matter hyperintensities (WMH). However, no study to date has examined the effects of cerebral blood flow, WMH, and brain volume on sleep quality in HF. Fifty-three HF patients completed the Pittsburgh Sleep Quality Index and underwent brain magnetic resonance imaging to quantify brain and WMH volume. Transcranial Doppler ultrasonography assessed cerebral blood flow velocity of the middle cerebral artery (CBF-V of the MCA). 75.5% of HF patients reported impaired sleep. Regression analyses adjusting for medical and demographic factors showed decreased CBF-V of the MCA and greater WMH volume were associated with poor sleep quality. No such pattern emerged on total brain or regional volume indices. Decreased cerebral perfusion and greater WMH may contribute to sleep difficulties in HF. Future studies are needed to confirm these findings and clarify the effects of cerebral blood flow and WMH on sleep in healthy and patient samples.
    Behavioral and Brain Functions 10/2013; 9(1):42. · 2.00 Impact Factor
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    ABSTRACT: Bariatric surgery is associated with improved cognition, and it is possible that such improvements are found at extended follow-ups. We hypothesized that cognitive improvement would be maintained 3 years after bariatric surgery. Fifty bariatric patients were recruited from the Longitudinal Assessment of Bariatric Surgery parent project. Participants completed a computerized cognitive test battery to assess cognitive function at 12 weeks, 12 months, 24 months, and 36 months after surgery. Repeated measures revealed main effects for attention, executive function, and memory. Attention improved up to 24 months and then slightly declined although it still fell within the average range at 36 months. Improvements in executive function reached their peak at 36 months after surgery. Short-term improvements in memory were maintained at 36 months. No main effect emerged for language. Bariatric surgery may lead to lasting improvements in cognition. Prospective studies with extended follow-ups (eg, 10 years) should examine whether bariatric surgery can attenuate cognitive decline in severely obese patients.
    American journal of surgery 10/2013; · 2.36 Impact Factor
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    ABSTRACT: Chronic systemic immune activation and inflammatory processes have been linked to brain dysfunction in medically stable HIV-infected people. We investigated the association between verbal memory performance and plasma concentrations of 13 cytokines measured using multiplexed bead array immunoassay in 74 HIV-seropositive individuals and 50 HIV-seronegative controls. Memory performance was positively related to levels of IL-8 and IFN-γ, and negatively related to IL-10 and IL-18 and to hepatitis C infection. Memory performance was not significantly related to HIV disease markers. The results indicate the importance of systemic immune and inflammatory markers to neurocognitive function in chronic and stable HIV disease.
    Journal of neuroimmunology 09/2013; · 2.84 Impact Factor
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    ABSTRACT: Exposure to early life trauma (ELT) is known to have a profound impact on mental development, leading to a higher risk for depression and anxiety. Our aim was to use multiple structural imaging methods to systematically investigate how traumatic stressors early in life impact the emotional brain circuits, typically found impaired with clinical diagnosis of depression and anxiety, across the lifespan in an otherwise healthy cohort. MRI data and self-reported histories of ELT from 352 healthy individuals screened for no psychiatric disorders were analyzed in this study. The volume and cortical thickness of the limbic and cingulate regions were assessed for all participants. A large subset of the cohort also had diffusion tensor imaging data, which was used to quantify white matter structural integrity of these regions. We found a significantly smaller amygdala volume and cortical thickness in the rostral anterior cingulate cortex associated with higher ELT exposure only for the adolescence group. White matter integrity of these regions was not affected. These findings demonstrate that exposure to early life trauma is associated with alterations in the gray matter of cingulate-limbic regions during adolescence in an otherwise healthy sample. These findings are interesting in the context that the affected regions are central neuroanatomical components in the psychopathology of depression, and adolescence is a peak period for risk and onset of the disorder.
    PLoS ONE 09/2013; 8(9):e75524. · 3.53 Impact Factor
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    ABSTRACT: Cerebral hypoperfusion is common in heart failure (HF) and believed to underlie poor neurocognitive outcomes in this population. Up to 42% of HF patients also exhibit depressive symptomatology that may stem from reduced cerebral blood flow. However, no study has examined this possibility or whether reduced brain perfusion increases risk for future cognitive dysfunction in older adults with HF. One hundred HF patients underwent transcranial Doppler ultrasonagraphy to quantify global cerebral blood flow velocity (CBF-V) and were administered a cognitive test battery to assess global cognition, attention/executive function, and memory abilities. All participants then completed the Beck Depression Inventory-II to assess depressive symptomatology. These procedures were performed at baseline and at 12-month follow-up. Repeated measures revealed that CBF-V declined over the 12-month period. Regression analyses showed that reduced baseline CBF-V predicted worse performances in attention/executive function (p < 0.05 for all) and a trend for memory (p = 0.09) in addition to greater depressive symptomatology (p < 0.05) at the 12-month follow-up, even after controlling for baseline factors and medical and demographic variables. Cerebral perfusion declined over time and was associated with poorer cognitive function and greater depressive symptoms at a 1-year follow-up in HF. Prospective studies with long-term follow-ups that employ neuroimaging are needed to examine whether cognitive dysfunction and depression in HF stem from the adverse effects of cerebral hypoperfusion on the cerebral structure. Copyright © 2013 John Wiley & Sons, Ltd.
    International Journal of Geriatric Psychiatry 09/2013; · 3.09 Impact Factor
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    ABSTRACT: ABSTRACT Cognitive impairment is prevalent in heart failure (HF), though substantial variability in the pattern of cognitive impairment is found across studies. To clarify the nature of cognitive impairment in HF, we examined longitudinal trajectories across multiple domains of cognition in HF patients using latent growth class modeling. 115 HF patients completed a neuropsychological battery at baseline, 3-months and 12-months. Participants also completed the Beck Depression Inventory-II (BDI-II). Latent class growth analyses revealed a three-class model for attention/executive function, four-class model for memory, and a three-class model for language. The slope for attention/executive function and language remained stable, while improvements were noted in memory performance. Education and BDI-II significantly predicted the intercept for attention/executive function and language abilities. The BDI-II also predicted baseline memory. The current findings suggest that multiple performance-based classes of neuropsychological test performance exist within cognitive domains, though case-controlled prospective studies with extended follow-ups are needed to fully elucidate changes and predictors of cognitive function in HF.
    Aging Neuropsychology and Cognition 08/2013; · 1.07 Impact Factor

Publication Stats

457 Citations
164.54 Total Impact Points

Institutions

  • 2013–2014
    • University of Florida
      Gainesville, Florida, United States
  • 2003–2014
    • Alpert Medical School - Brown University
      • Department of Psychiatry and Human Behavior
      Providence, Rhode Island, United States
  • 2011–2013
    • Kent State University
      • Department of Psychology
      Kent, OH, United States
  • 2010–2013
    • Brown University
      • • Department of Psychiatry and Human Behavior
      • • Department of Medicine
      Providence, Rhode Island, United States
  • 2011–2012
    • Rhode Island Hospital
      Providence, Rhode Island, United States
  • 2009
    • Brigham and Women's Hospital
      • Department of Medicine
      Boston, MA, United States
  • 2002
    • Providence Hospital
      Mobile, Alabama, United States