Vonetta M. Dotson

Recurrent depressive symptoms and the incidence of dementia and mild cognitive impairment

Objective: A history of depression has been linked to an increased dementia risk. This risk may be particularly high in recurrent depression due to repeated brain insult. We investigated whether there is a dose-dependent relationship between the number of episodes of elevated depressive symptoms (EDS) and the risk for mild cognitive impairment (MCI) and dementia. Methods: A total of 1,239 older adults from the Baltimore Longitudinal Study of Aging were followed for a median of 24.7 years. Diagnoses of MCI and dementia were made based on prospective data. Participants completed the Center for Epidemiologic Studies Depression Scale at 1- to 2-year intervals and were considered to have an EDS if their score was ≥16. Kaplan-Meier survival curves, log-rank test for trend for survivor functions, and Cox proportional hazards models were conducted to examine the risk of MCI and dementia by number of EDS. Results: We observed a monotonic increase in risk for all-cause dementia and Alzheimer disease as a function of the number of EDS. Each episode was associated with a 14% increase in risk for all-cause dementia. Having 1 EDS conferred an 87%–92% increase in dementia risk, while having 2 or more episodes nearly doubled the risk. Recurrence of EDS did not increase the risk of incident MCI. Conclusions: Our findings support the hypothesis that depression is a risk factor for dementia and suggest that recurrent depression is particularly pernicious. Preventing the recurrence of depression in older adults may prevent or delay the onset of dementia.

Differential Association of Concurrent, Baseline, and Average Depressive Symptoms With Cognitive Decline in Older Adults

OBJECTIVES The impact of depressive symptoms on cognitive decline in older adults remains unclear due to inconsistent findings in the literature. It is also unclear whether effects of depressive symptoms on cognitive decline vary with age. This study investigated the effect of concurrent, baseline, and average depressive symptoms on cognitive functioning and decline, and examined the interactive effect of age and depressive symptoms on cognition. DESIGN Prospective observational design with examination of cognitive performance and depressive symptoms at 1- to 2-year intervals for up to 26 years. SETTING Baltimore Longitudinal Study of Aging, National Institute on Aging. PARTICIPANTS One thousand five hundred eighty-six dementia-free adults 50 years of age and older. MEASUREMENTS Scores over time on the Center for Epidemiologic Studies Depression Scale and measures of learning and memory, attention and executive functions, verbal and language abilities, visuospatial functioning, and general cognitive status. RESULTS Increased depressive symptoms were associated with poor cognitive functioning and cognitive decline in multiple domains. Concurrent, baseline, and average depressive symptoms had differential associations with cognition. Average depressive symptoms, a measure of chronic symptoms, seemed to show the most widespread effects on cognitive abilities. Effects of depressive symptoms on some frontal functions were greater with advancing age. CONCLUSION Depressive symptoms are associated with poor cognitive functioning and cognitive decline, particularly with advancing age. The widespread impact of average depressive symptoms on cognition suggests that clinicians should consider the chronicity of depressive symptoms when evaluating cognitive functioning in older adults.

Temporal dissociation of components of cognitive control dysfunction in severe TBI: ERPs and the cued-Stroop task.

Cognitive control comprises two essential interactive component processes: a regulative component supporting the activation and implementation of control and an evaluative component that monitors the need for regulative control and signals when adjustments in control are necessary. Survivors of severe traumatic brain injury (TBI) experience cognitive control impairments, but the specific nature of these impairments is poorly characterized. Using event-related potentials (ERPs) acquired in the context of a trial-by-trial task-switching version of the Stroop task we temporally dissociated the regulative and evaluative processes in order to shed light on the potential roles of these components in TBI-related cognitive control impairment. Behaviorally, TBI patients showed a specific performance deficit suggestive of a failure to implement cognitive control in the service of processing conflict information. ERP findings showed that TBI patients were impaired in both the implementation of control and subsequent detection and processing of conflict. TBI patients were also impaired on a measure of working memory capacity, a measure that correlated with the ability to implement regulative control and overcome conflict. These findings suggest that patients with predominantly chronic severe TBI patients are impaired on both regulative and evaluative components of cognitive control, and may have implications for the design and evaluation of behavioral and pharmacological remediation strategies.

Effects of race and socioeconomic status on the relative influence of education and literacy on cognitive functioning.

Previous research has shown that reading ability is a stronger predictor of cognitive functioning than years of education, particularly for African Americans. The current study was designed to determine whether the relative influence of literacy and education on cognitive abilities varies as a function of race or socioeconomic status (SES). We examined the unique influence of education and reading scores on a range of cognitive tests in low- and higher-SES African Americans and Whites. Literacy significantly predicted scores on all but one cognitive measure in both African American groups and low-SES Whites, while education was not significantly associated with any cognitive measure. In contrast, both education and reading scores predicted performance on many cognitive measures in higher-SES Whites. These findings provide further evidence that reading ability better predicts cognitive functioning than years of education and suggest that disadvantages associated with racial minority status and low SES affect the relative influence of literacy and years of education on cognition.

Longitudinal study of chronic depressive symptoms and regional cerebral blood flow in older men and women

Late‐life depression is associated with alterations in regional cerebral blood flow (rCBF) and metabolism in a neural network that includes frontostriatal and limbic regions and the cerebellum. Prior studies suggest that clinical depression and subthreshold depressive symptoms (SDS) are associated with similar cognitive deficits and structural brain changes, but little is known about the relationship between SDS and patterns of brain activity. Additionally, the neural correlates of depression have not been fully explored in men and women separately. This study investigated cross‐sectional and longitudinal relationships between SDS and rCBF in older men and women.

Depressive Symptoms, Brain Volumes and Subclinical Cerebrovascular Disease in Postmenopausal Women: The Women’s Health Initiative MRI Study

OBJECTIVE Late-life depressive symptoms (DS) increase the risk of incident mild cognitive impairment and probable dementia in the elderly. Our objectives were to examine the relationship between elevated DS and regional brain volumes including frontal lobe subregions, hippocampus and amygdala, and to determine whether elevated DS were associated with increased subclinical cerebrovascular disease in postmenopausal women. METHODS DS were assessed an average of 8years prior to structural brain MRI in 1372 women. The 8-item Burnam regression algorithm was used to define DS with a cut-point of 0.009. Adjusting for potential confounders, mean differences in total brain, frontal lobe subregions, hippocampus and amygdala volumes and total ischemic lesion volumes in the basal ganglia and the cerebral white and gray matter outside the basal ganglia were compared between women with and without DS. RESULTS Depressed women had lower baseline global cognition and were more likely to have prior hormone therapy history. After full adjustment, DS at baseline were associated with smaller superior and middle frontal gyral volumes. Hippocampal and amygdala volumes, and ischemic lesion volumes were similar in depressed and non-depressed women. LIMITATIONS Depression was not assessed based on semi-structured interview, and MRI scans were obtained cross-sectionally rather than longitudinally. Longitudinal MRI assessments will be necessary to define the temporal relationships between DS and frontal lobe volumes. CONCLUSIONS Elevated DS were associated with lower volumes in certain frontal lobe subregions but not in the medial temporal lobe structures. Our findings support the role of frontal lobe structures in late-life DS among women.

Literacy-based normative data for low socioeconomic status African Americans

Clinical neuropsychology relies on the use of appropriate test norms. Normative studies frequently stratify based on age, education, sex, and race. None to date has reported norms based on literacy, despite the substantial evidence that literacy impacts cognitive functioning. Some researchers have suggested that literacy is a more accurate reflection of academic achievement and quality of education than years of education, particularly for African Americans. The current study provides literacy-based normative data for multiple neuropsychological measures based on a sample of predominantly low socioeconomic status African Americans. These normative data should improve the diagnostic accuracy of performances by African-American clients with similar demographic backgrounds.

Depressive symptoms, symptom dimensions, and white matter lesion volume in older adults: a longitudinal study.

OBJECTIVE White matter lesions (WMLs) are associated with depressive symptoms in older adults. However, it is not clear whether different symptom dimensions of depression have distinct associations with WMLs. The authors assessed the longitudinal relationships of the Center for Epidemiologic Studies Depression Scale (CES-D) total score and subscale scores with WML volume in the Baltimore Longitudinal Study of Aging. METHODS Using a prospective observational design, the authors examined WML volume and depressive symptoms at 1- to 2-year intervals for up to 9 years in 116 dementia-free participants (mean age: 68.78 ± 7.68). At each visit, depressive symptoms were measured with the CES-D and WML volumes were quantified from structural magnetic resonance imaging scans. RESULTS Higher CES-D full-scale scores were associated with greater WML volume and with a faster rate of volume increases over time in women, especially at older ages. Higher depressed mood and somatic symptoms subscale scores were associated with greater increases in WML volume over time at older ages. In men, depressed mood and somatic symptoms were associated with larger WML volume at baseline. CONCLUSION Findings confirm an association between WMLs and depressive symptoms and suggest that depressed mood and somatic symptoms may be stronger predictors of depression-related brain changes than lack of well-being. Age and sex may moderate the relationships between depressive symptoms and WMLs. Understanding particular symptom dimensions of depressive symptoms has implications for treatment and may lead to targeted interventions and more precise knowledge of mechanisms underlying depression.

Unique and Interactive Effect of Anxiety and Depressive Symptoms on Cognitive and Brain Function in Young and Older Adults

OBJECTIVE Depression and anxiety and are associated with cognitive deficits and brain changes, especially in older adults. Despite the frequent co-occurrence of these conditions, cognitive neuroscience studies examining comorbid depression and anxiety are limited. The goal of the present study was to examine the unique and combined effect of depressive and anxiety symptoms on cognitive and brain functioning in young and older adults. METHODS Seventy-one healthy, community-dwelling adults between the ages of 18 and 81 were administered a neuropsychological battery and completed the Center for Epidemiologic Studies Depression Scale (CES-D) and the trait form of the State-Trait Anxiety Inventory (STAI-T). A subset of 25 participants also underwent functional magnetic resonance imaging (fMRI) scanning while completing the n-back working memory task. RESULTS Total depressive symptoms, depressed mood symptoms, and somatic symptoms were associated with deficits in speed, working memory and executive functions, especially in older adults. Symptoms of lack of well-being were not associated with any neuropsychological test. Anxiety was associated with better attention and working memory. Moreover, anxiety modified the relationship between depressive symptoms and executive functioning in older adults, as elevated depressive symptoms were associated with worse performance at low levels of anxiety, but not at higher anxiety levels. Similarly, analysis of fMRI data showed that total depressive symptoms and depressed mood symptoms were associated with decreased activity in the superior frontal gyrus at low anxiety levels, but not at high anxiety levels. CONCLUSION Results confirm previous reports that subthreshold depression and anxiety impact cognitive and brain functioning and suggest that the interaction of depression and anxiety results in distinct cognitive and brain changes. Findings highlight the importance of assessing and controlling for symptoms of depression and anxiety in research studies of either condition.

Temporal relationships between depressive symptoms and white matter hyperintensities in older men and women

Associations between vascular disease and depression in late life, including increased white matter hyperintensities (WMHs), have been reported. Whether depression is an etiology or a consequence of vascular disease is still unknown. We investigated the temporal relationship between depressive symptoms and WMHs in older men and women.