2011 Student Research
Prefrontal white matter volume and systolic blood pressure mediate age-related differences in processing speed and working memory in ApoE ε4 carriers
Andrew R. Bender, M.A. and Naftali Raz, Ph. D.
Introduction: Advanced age and vascular risk factors are associated with declines in prefrontal cortical and white matter volumes, executive functions, and processing speed in healthy adults. Carriers of the ε4 allele of the apolipoprotein E (ApoE) gene, a known risk factor for dementia, show greater age-associated vascular damage and decreased cognitive functioning in comparison to non-carriers.
Methods: In the present study, we examined the effects of a vascular health indicator (blood pressure, BP), volumes of dorsolateral prefrontal cortex (dlPFC) and prefrontal white matter (pFWM) on two age-sensitive cognitive functions: processing speed (PS) and working memory (WM) in healthy adults (age 19-77). Path analyses modeled indirect effects of age, systolic BP, and brain volumes on PS and WM for ε4 carriers and ε3 homozygotes.
Results: Among ε4 carriers, age differences in WM were mediated by increase in systolic BP via reduced FWM volume via slower PS. In contrast, dlPFC and FWM volumes, but not BP, mediated the effects of age on working memory among ε3 homozygotes.
Conclusions: These findings show that even in healthy adults, the ApoE ε4 allele may produce a phenotypic pattern, in which increased age and vascular risk negatively affect FWM volume and therefore impair cognitive functions.
Age-related differences in spatial navigation are mediated by increased iron presence in the basal ganglia
Ana M. Daugherty, M.A. & Naftali Raz, Ph.D.
Introduction: Aging is associated with declines in multiple cognitive domains, including spatial navigation. Age-related alterations of brain metabolism that result in increased deposition of iron have been proposed as predictors of cognitive declines in later life. In some studies, elevation of brain iron has been linked to increased cardiovascular risk
Methods: In this study we examined the relationship between in vivo estimates of non-heme iron (∆R2*), cardiovascular risk, and spatial navigation in healthy adults (age 19-79 years). ∆R2* was manually measured from susceptibility-weighted magnitude images across several subcortical regions. In a structural equation model, cardiovascular risk was a composite of hypertension classification, and blood serum glucose, low-density lipids, and total cholesterol concentrations.
Results & Conclusions: Advanced age was associated with an increase in non-heme iron in the basal ganglia, hippocampus, and insula cortex, but not in the corpus callosum. Elevated cardiovascular risk was unrelated to regional differences in ∆R2*. Increased iron content in the basal ganglia (but not in the hippocampus) predicted deficits in the spatial navigation task (virtual Morris Water Maze), and mediated age-related differences therein. Thus, increase in non-heme iron in the basal ganglia of healthy adults may be a sensitive marker of cognitive declines.
Efficacy of a Train-the-Trainer Curriculum for Occupational Therapists’ Mental Health Knowledge
Cathy Lysack, Ph.D., Carrie Leach, M.P.A.,
Peter Lichtenberg, Ph.D., Daniel Paulson, M.A,
Theresa Russo, B.S
Introduction: Although occupational therapists (OTs) are trained in mental health assessment and intervention, these skills are under-utilized in clinical practice with older adults. The purpose of this study was to assess the efficacy of a 7-DVD set of depression training materials (Lysack et al., in press) utilizing a randomized control trial research design to measure a train-the-trainer (TTT) curriculum on therapists’ pre and post training knowledge.
Methods: Baseline testing was conducted for all OTs (n=70) before any training was conducted to measure pre-training knowledge. The TTT curriculum consisted of one 2-day intensive training. The trainers then conducted training for their OT staff. Testing on all OTs was conducted after training was completed for all OTs in the intervention (n=37) and control groups (n=33). A 2X2 Repeated Measures Analysis of Variance was performed.
Results: The intervention group significantly improved their knowledge at post test (from 61 to 78% correct responses) whereas the control group remained at 61% correct at both testing time-points (F=32.245; p<.05).
Conclusions: The TTT model was efficacious in increasing OTs knowledge regarding mental health in late life. Given major shortfalls in the recognition and treatment of late life depression, the study emphasizes the importance of mental health screening, particularly in older adults.
Longevity Assurance Gene’s (LASS1) Relationship with Electrophysiological Correlates of Wayfinding and Cue Recognition Memory in a Virtual Environment
John Dillon, B.S., Scott Moffat, Ph.D., Voyko Kavcic, Ph.D.
Introduction: Spatial cognition literature identifies preference for cues at directional decision points of an environment (critical) over non-critical cues in recognition memory. The current study seeks to identify electrophysiological correlates of successful cue encoding and impact of cue preference on subsequent spatial memory.
Methods: EEG was recorded according to International 10-20 system and ERPs analyzed for a prototypical subject. Participants navigated through a virtual environment (VE) consisting of interconnected hallways containing cues at critical and non-critical points. After learning the VE, cue recognition was tested, identifying prior cues. Subjects were also given a spatial memory test, identifying the goal direction from VE stills from several headings.
Results: Reaction times were lower and hits greater for critical cues in either task. ERPs from a prototypical subject with well-defined waveforms revealed higher P300 amplitudes (300-400ms after onset) in recognition memory parietally, and late positivity frontally for spatial memory. Both components demonstrated hemispheric asymmetry, with greater right frontal and left parietal amplitudes.
Conclusions: Findings reveal critical cue preference and reflect its spatial utility, echoing neuroanatomical correlates of wayfinding. Additional data is necessary, as the data may not be representative of the population. Still, the results suggest this method should elaborate on preference and its spatial memory impact.
Medicare Part D and Its Impact on Racial/Ethnic Disparities in Access to Prescription Medications
Elham Mahmoudi, Ph.D. Candidate, Gail A. Jensen, Ph.D.
Introduction: This study evaluates the effect of Medicare Part D on racial/ethnic disparities in access to prescription medications. Medicare Part D, implemented in January 2006, is the most extensive addition to Medicare since 1965.
Methods:. Medical Expenditure Panel Survey (MEPS) data covering 2003 through 2008 is used for the analysis. Two measures of access are examined: whether an individual has prescription drug insurance, and the number of prescriptions actually filled during the year. A “pre-post-with-comparison-group” quasi-experimental design is implemented using the framework of multivariate regression analysis. Specifically, a regression-based difference-in-differences (DD) estimator is adopted. Three alternative definitions for a “disparity” between a minority group and Whites are explored, specifically, the AHRQ definition, the IOM definition, and the “Residual Direct Effect” definition.
Results: Medicare Part D increased Access to prescription medications among all seniors. It did not, however, have any significant effects on reducing racial/ethnic disparities in access to prescription medications.
Conclusions: Failure of Medicare Part D in reducing disparities might be the result of over complications of the program. In addition, many eligible low-income beneficiaries are unaware of Medicare Part D’s subsidies. Additional intervention for disadvantaged and minorities might be needed.
Examining Anxiety Sensitivity Index (ASI)
Scores Longitudinally in Older Adults
Pamela E. May, M.A., John L. Woodard, Ph.D., John E. Calamari, Ph.D., Moira Dux, Ph.D., Michael Messina, Ph.D., Noelle Pontarelli, M.A., Jami Socha, M.A., Brandon DeJong, M.S., and Kerrie M. Armstrong, B.A.
Wayne State University, Rosalind Franklin University, Department of Veterans Affairs, Baltimore, Department of Veterans Affairs, Ann Arbor
Objective: The Anxiety Sensitivity Index (ASI) was developed to assess anxiety sensitivity (AS), fears of symptoms related to anxiety and panic. The developers of the ASI conceptualized AS as a stable trait. Given the wide use of the ASI and the paucity of studies on late-life AS, latent growth curve modeling (LGC) was conducted to test the stability of ASI scores over two years in older adults.
Methods: At baseline, 204 participants (Mage = 76.7 years) were recruited from senior centers. Data were collected across four time points at six-month intervals. Participants completed self-report measures, such as the ASI, at home.
Results: LGC was used to examine ASI ratings across four time points. Mean ASI scores decreased over time, indicating less fear of anxiety. An intercept-only model was first specified; there was disagreement among fit indices. To examine ASI scores over time, a linear slope was added to the model; this additional parameter improved model fit.
Conclusions: Findings suggest that older adults’ AS might vary over time. ASI scores were best modeled with two factors, an intercept and slope, and they typically decreased over time. Further research is needed to examine the nature of longitudinal AS changes in older adults.
Vascular Depression and Frailty: A Compound Threat to Longevity among Older-Old Women
Daniel Paulson, M.A., TLLP, Peter A. Lichtenberg, Ph.D., ABPP
Introduction: Vascular depression theory posits that high cerebrovascular burden predisposes, precipitates and perpetuates development of depression symptoms in late life (Alexopoulos et al., 1997). Building on past work suggesting that vascular depression is a prodrome for frailty (Paulson & Lichtenberg, 2011), this paper tests a theoretical framework that vascular depression symptoms are an early marker of a broader pattern of decline characterized by more frailty symptoms and shortened lifespan. The specific hypothesis tested in this model is that depression predicts mortality through frailty.
Methods: The sample, drawn from the Health and Retirement Study, includes 1361 stroke-free women over the age of 80. A 5-level vascular depression variable was based on CES-D scores and number of cerebrovascular risk factors. Frailty was measured as a semi-continuous variable based wasting, slowness, weakness, fatigue and falls (score 0-6). Vascular depression and frailty symptoms were modeled using slope and intercept terms. Mortality was modeled using a discrete-time survival term.
Results: The data supported the proposed model (RMSEA=.051; CFI=.971; X2=429.27, p<.001). Higher vascular depression symptom slope predicted higher frailty symptom slope (β= .23, p=.02). Higher vascular depression intercept values significantly predicted higher frailty intercept term values (β=.42, p<.001), which predicted probability of mortality (β=.07, p=.04). Additionally, vascular depression symptoms significantly predicted mortality through frailty symptoms (β=.03, p=.04).
Conclusions: Our results support the proposed theoretical framework and suggest that vascular depression symptoms are associated with a clinical trajectory including more frailty symptoms and shorted remaining lifespan. This finding supports integrated care for geriatric patients and suggests specific targets for intervention with older patients experiencing vascular depression symptoms.
Depression, Cognitive Functioning and Mortality in an Physical health variables predict additional variance in late-life cognitive, memory, mood and functional outcomes beyond demographics.
Annalise Rahman, John L.Woodard, L. Stephen Miller, Peter Martin, Adam Davey & Leonard W. Poon
Wayne State University, University of Georgia, Iowa State University, Temple University
Introduction: Physical ability and nutritional status can strongly influence cognition and mood in late-life, but the nature of their effects has not been well-investigated among the oldest-old. We investigated the influence of physical performance, nutritional status, and body mass index (BMI) on cognition, mood, and functional capacity in centenarians and octogenarians.
Methods: Eighty octogenarians and 244 centenarians from the Georgia Centenarian Study completed evaluations of cognition, mood, functional capacity, physical performance and nutritional status. Hierarchical regressions evaluated the incremental predictive value of physical health factors beyond demographic variables (age, gender, ethnicity, education). The Physical Performance Mobility Exam (PPME), Mini-Nutritional Assessment (MNA) and Body Mass Index (BMI) were entered on the second step. Outcome measures included the Mini-Mental State Examination, Fuld Object Memory Evaluation, Geriatric Depression Scale (GDS), and Direct Assessment of Functional Status.
Results: A model including demographic variables and the PPME, MNA and BMI accounted for significantly more variance in global cognition, memory, mood and functional capacity than a model including only demographic predictors. Physical performance and nutrition accounted for more variance in GDS score than demographic factors.
Conclusions: Physical performance and nutritional status have substantial influences on cognition, mood and functional capacity in the oldest old, even after adjustment for demographic factors.
White Matter Hyperintensities, Metabolic Syndrome Risk, and Cognitive Performance in Healthy Middle-Aged and Older Adults
Yiqin Yang, M.A. & Naftali Raz, Ph.D.
Introduction: Advanced age is associated with reduced performance in multiple cognitive domains. However, the reasons for age differences are poorly understood. In this study of 161 healthy volunteers we investigated whether age-related differences in episodic memory (EM), executive functions (EF), and speed of processing (Speed), are mediated by individual variation in cerebral white matter and vascular/metabolic risk.
Methods: We measured volume of periventricular (PV) and deep (D) white matter hyperintensities (WMH) as well as components of the Metabolic Syndrome Score (hypertension status, fasting glucose, high-density lipoprotein, triglyceride, and waist circumference). We tested the mediation hypotheses using Structural Equation Modeling (SEM).
Results: In SEM, a latent factor formed by the measures of metabolic syndrome components (MetS) was unrelated to age and showed no effect on cognition. The latent construct formed by WMH volumes in four brain lobes showed a reliable increase with age but no role in mediating age differences in cognitive measures. However, a separate analysis of PV-WMH and D-WMH revealed that the latter mediated age differences in EF and EM but not Speed.
Conclusions: Normal range metabolic/vascular risk indicators do not contribute significantly to age differences in cognition in healthy adults.
Change of Movement Direction: A study on Turning Behaviors in Virtual Morris Water Maze
Peng Yuan, B.A.
Introduction: Morris Water Maze (MWM) is a popular test of navigation skill. Traditional MWM-derived behavioral indices of navigational proficiency have demonstrated age-related deficit in navigation performance. However, these indices don’t inform about the shape of the tracks and the trajectory of search.
Methods: In the current study of human navigation in a virtual MWM (vMWM), we introduced a new measure that provided information about that neglected aspect of navigational behavior by quantifying changes of participants’ movement vectors. The cumulative change of movement direction served as a major index of turning. We hypothesized that older age and female gender would be associated with larger turning angle.
Results: The total turning angles increased with age, and were larger in women than in men. Older participants and women lost direction more frequently than younger participants and men did. Older participants evidenced a higher proportion right (clockwise) turns than did their younger counterparts.
Conclusions: The measures introduced provided information about participants’ turning behaviors in vMWM. The change of movement direction could serve as an index of wandering and may supplement current measures of navigational behavior.