Ronald Cohen

University of Florida, Gainesville, Florida, United States

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Publications (53)123.96 Total impact

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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;
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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;
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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: 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; · 0.86 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; · 3.83 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 01/2014; · 4.12 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 01/2014; · 2.32 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. · 2.79 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: 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; · 2.98 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
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    ABSTRACT: Objective Depression is common among persons with heart failure (HF) and has been linked to cognitive impairment in this population. The mechanisms of this relationship are unclear, and the current study examined whether cerebral perfusion moderates the association between depressive symptoms and cognitive impairment in patients with HF.Methods Persons with HF (n = 89; mean [standard deviation] age = 67.61 [11.78] years) completed neuropsychological testing and impedance cardiography. Depressive symptoms were assessed using the Beck Depression Inventory II, and transcranial Doppler was used to quantify cerebral perfusion.ResultsDepression was associated with reduced performance on tasks assessing attention/executive function (r = -0.28), language (r = -0.0.30), and motor function (r = -0.28) in unadjusted models (p values <.05). Global cerebral blood flow was correlated with memory performance (r = 0.22, p = .040) but not with other tasks. A moderation analysis was performed using hierarchical regression models for attention/executive function, memory, language, and motor function. For each model, medical and demographic characteristics were entered into the initial blocks, and the final block consisted of an interaction term between global cerebral blood flow velocity and the Beck Depression Inventory II. The interaction between greater depressive symptoms and decreased global cerebral blood flow velocity was associated with greater deficits in attention/executive function (β = .32, ΔR(2) = 0.08, p = .003).Conclusions Depressive symptoms and cerebral hypoperfusion interact to adversely affect cognitive performance in older adults with HF. Longitudinal studies are needed to clarify this relationship and elucidate subsequent neuropathology.
    Psychosomatic Medicine 07/2013; · 4.08 Impact Factor
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    ABSTRACT: Background:Occurrences of impaired activities of daily living (ADL) are common in heart failure (HF) patients and contribute to the elevated mortality and hospitalization rates in this population. Cognitive impairment is also prevalent in HF, though its ability to predict functional decline over time is unknown.Aims:This study examined the longitudinal pattern of activities of daily living (ADL) in HF persons and whether reduced baseline cognitive status predicts functional decline in this population.Methods:Altogether 110 persons with HF completed the Lawton-Brody Instrumental Activities of Daily Living (IADL) scale and were administered the Modified Mini-Mental Status Examination (3MS) at baseline and a 12-month follow-up. Three composite scores were derived from the Lawton-Brody scale, including total, instrumental, and basic ADL.Results:HF patients reported high rates of baseline impairments in instrumental ADL, including shopping, food preparation, housekeeping duties, laundry, among others. Repeated measures analyses showed significant declines in total and instrumental ADL from baseline to the 12-month follow-up in HF (p<0.05). Hierarchical regression analyses showed that poorer baseline performance on the 3MS predicted worse total ADL performance at 12-months (β=0.15, p=0.049), including greater dependence in shopping, driving, feeding, and physical ambulation (p<0.05 for all).Conclusion:The current results show that HF patients report significant functional decline over a 12-month period and brief cognitive tests can identify those patients at highest risk for decline. If replicated, such findings encourage the use of cognitive screening measures to identify HF patients most likely to require assistance with ADL tasks.
    European Journal of Cardiovascular Nursing 06/2013; · 2.04 Impact Factor
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    ABSTRACT: BACKGROUND: Reduced systemic perfusion and comorbid medical conditions are key contributors to adverse brain changes in heart failure (HF). Hypertension, the most common co-occurring condition in HF, accelerates brain atrophy in aging populations. However, the independent and interactive effects of blood pressure and systemic perfusion on brain structure in HF have yet to be investigated. METHODS: Forty-eight older adults with HF underwent impedance cardiography to assess current systolic blood pressure status and cardiac index to quantify systemic perfusion. All participants underwent brain magnetic resonance imaging to quantify total brain, total and subcortical gray matter volume, and white matter hyperintensities (WMH) volume. RESULTS: Regression analyses adjusting for medical and demographic factors showed decreased cardiac index was associated with smaller subcortical gray matter volume (P < .01), and higher systolic blood pressure predicted reduced total gray matter volume (P = .03). The combination of higher blood pressure and lower cardiac index exacerbated WMH (P = .048). CONCLUSIONS: Higher blood pressure and systemic hypoperfusion are associated with smaller brain volume, and these factors interact to exacerbate WMH in HF. Prospective studies are needed to clarify the effects of blood pressure on the brain in HF, including the role of long-term blood pressure fluctuations.
    Journal of the American Society of Hypertension (JASH) 06/2013;
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    ABSTRACT: AIMS AND OBJECTIVES: To examine the independent association between executive function with instrumental activities of daily living and health behaviours in older adults with heart failure. BACKGROUND: Executive function is an important contributor to functional independence as it consists of cognitive processes needed for decision-making, planning, organising and behavioural monitoring. Impairment in this domain is common in heart failure patients and associated with reduced performance of instrumental activities of daily living in many medical and neurological populations. However, the contribution of executive functions to functional independence and healthy lifestyle choices in heart failure patients has not been fully examined. DESIGN: Cross-sectional analyses. METHODS: One hundred and seventy-five heart failure patients completed a neuropsychological battery and echocardiogram. Participants also completed the Lawton-Brody Instrumental Activities of Daily Living Scale and reported current cigarette use. RESULTS: Hierarchical regressions revealed that reduced executive function was independently associated with worse instrumental activity of daily living performance with a specific association for decreased ability to manage medications. Partial correlations showed that executive dysfunction was associated with current cigarette use. CONCLUSIONS: Our findings suggest that executive dysfunction is associated with poorer functional independence and contributes to unhealthy behaviours in heart failure. Future studies should examine whether heart failure patients benefit from formal organisation schema (i.e. pill organisers) to maintain independence. RELEVANCE TO CLINICAL PRACTICE: Screening of executive function in heart failure patients may provide key insight into their ability to perform daily tasks, including the management of treatment recommendations.
    Journal of Clinical Nursing 05/2013; · 1.32 Impact Factor
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    ABSTRACT: Clinically significant cognitive impairment, particularly in attention/executive and memory function, is found in many patients undergoing bariatric surgery. These difficulties have previously been linked to decreased weight loss 12 months after surgery, but more protracted examination of this relationship has not yet been conducted. The present study prospectively examined the independent contribution of cognitive function to weight loss 24 months after bariatric surgery. Given the rapid rate of cognitive improvement observed after surgery, postoperative cognitive function (i.e., cognition 12 weeks after surgery, controlling for baseline cognition) was expected to predict lower body mass index (BMI) and higher percent total weight loss (%WL) at 24-month follow-up. Data were collected by 3 sites of the Longitudinal Assessment of Bariatric Surgery (LABS) parent project. Fifty-seven individuals enrolled in the LABS project who were undergoing bariatric surgery completed cognitive evaluation at baseline, 12 weeks, and 24 months. BMI and %WL were calculated for 24-month postoperative follow-up. Better cognitive function 12 weeks after surgery predicted higher %WL and lower BMI at 24 months, and specific domains of attention/executive and memory function were robustly related to decreased BMI and greater %WL at 24 months. Results show that cognitive performance shortly after bariatric surgery predicts greater long-term %WL and lower BMI 24 months after bariatric surgery. Further work is needed to clarify the degree to which this relationship is mediated by adherence to postoperative guidelines.
    Surgery for Obesity and Related Diseases 05/2013; · 4.12 Impact Factor
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    ABSTRACT: Objective: Obesity is as an independent risk factor for poor neurocognitive outcomes, including Alzheimer's disease. Bariatric surgery has recently been shown to result in improved memory at 12-weeks post-operatively. However, the long-term effects of bariatric surgery on cognitive function remain unclear. Design and Methods: 86 individuals (63 bariatric surgery patients, 23 obese controls) were recruited from a prospective study examining the neurocognitive effects of bariatric surgery. All participants completed self-report measurements and a computerized cognitive test battery prior to surgery and at 12-week and 24-month follow-up; obese controls completed measures at equivalent time points. Results: Bariatric surgery patients exhibited high rates of pre-operative cognitive impairments in attention, executive function, memory, and language. Relative to obese controls, repeated measures ANOVA showed improvements in memory from baseline to 12-weeks and 24-months post-operatively (p <.05). Regression analyses controlling for baseline factors revealed that a lower BMI at 24-months demonstrated a trend toward significance for improved memory (β = -.30, p =.075). Conclusion: These findings suggest that cognitive benefits of bariatric surgery may extend to 24-months post-operatively. Larger prospective studies with extended follow-up periods are needed to elucidate whether bariatric surgery decreases risk for cognitive decline and possibly the development of dementia.
    Obesity 04/2013; · 3.92 Impact Factor
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    ABSTRACT: BACKGROUND: Reduced cognitive function is common in persons with heart failure (HF). Cardiovascular fitness is a known contributor to cognitive function in many patient populations, but has only been linked to cognition based on estimates of fitness in HF. The current study examined the relationship between fitness as measured by metabolic equivalents (METs) from a standardized stress test and cognition in persons with HF, as well as the validity of office-based predictors of fitness in this population. METHODS: Forty-one HF patients enrolled in cardiac rehabilitation completed a standardized exercise stress test protocol, a brief neuropsychological battery, the 2-minute step test (2MST), and a series of medical history and self-report questionnaires. RESULTS: Maximum METs from stress testing demonstrated incremental predictive validity for attention (beta = .41, p = .03), executive function (beta = .37, p = .04), and memory domains (beta = .46, p = .04). Partial correlations accounting for key medical and demographic characteristics revealed greater METs was associated with the 2MST (r (32) = .41, p = .02) but not with the Duke Activity Status Index (DASI) (r(32) = .24, p = .17). CONCLUSION: The current findings indicate that better fitness levels measured by METs is independently associated with better cognitive function in older adults with HF. Results also showed that METs was closely associated with one office-based measure of fitness (2MST), but not another (DASI). Prospective studies are needed to clarify the mechanisms linking fitness and cognitive function in HF.
    BMC Cardiovascular Disorders 04/2013; 13(1):29. · 1.46 Impact Factor

Publication Stats

391 Citations
123.96 Total Impact Points


  • 2013–2014
    • University of Florida
      Gainesville, Florida, United States
  • 2011–2013
    • Kent State University
      • Department of Psychology
      Kent, OH, United States
  • 2011–2012
    • Rhode Island Hospital
      Providence, Rhode Island, United States
  • 2010–2012
    • Brown University
      • • Department of Psychiatry and Human Behavior
      • • Department of Medicine
      Providence, Rhode Island, United States
    • Florida State University
      • Department of Statistics
      Tallahassee, FL, United States
  • 2003–2011
    • Alpert Medical School - Brown University
      • Department of Psychiatry and Human Behavior
      Providence, Rhode Island, United States
  • 2009
    • Brigham and Women's Hospital
      • Department of Medicine
      Boston, MA, United States
  • 2008
    • University of Missouri
      Columbia, Missouri, United States