Age-associated cognitive changes in community dwelling adults

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Although clinical cardiovascular and cerebrovascular diseases are established risk factors for cognitive decline and dementia, less is known about the relations between vascular health and cognition among individuals without these diseases. Carotid intimal medial thickness (IMT), a measure of subclinical vascular disease, is associated with concurrent decrements in cognitive function, but relatively little research has examined longitudinal relations between carotid IMT and prospective cognitive decline. We examined relations of carotid IMT to prospective trajectories of cognitive function among 538 (aged 20 to 93, 39% male, 66% white) participants in the Baltimore Longitudinal Study of Aging (BLSA) free of known cardiovascular, cerebrovascular, and neurological disease. Participants underwent initial carotid ultrasonography and repeat neuropsychological testing on up to 8 occasions over up to 11 years of follow-up. Mixed-effects regression analyses were adjusted for age, gender, race, education, mean arterial pressure, body mass index, total cholesterol, smoking, depressive symptoms, and cardiovascular medication use. Individuals with greater carotid IMT displayed accelerated decline in performance over time on multiple tests of verbal and nonverbal memory, as well as a test of semantic association fluency and executive function. Carotid IMT predicts accelerated cognitive decline, particularly in the domain of memory, among community-dwelling individuals free of vascular and neurological disease. In a second study, we examined the relation between longitudinal trajectories of depressive symptoms as well as history of significant symptoms and subsequent carotid intimal medial thickness (IMT) among participants enrolled in the Baltimore Longitudinal Study of Aging. We also assessed longitudinal covariation of depressive symptoms and carotid IMT over two time points. Prior literature has identified inconsistent cross-sectional associations between depressive symptoms and carotid IMT in healthy persons, and existing longitudinal work has relied on depression assessment at a single time point. Our sample include 556 participants (303 women and 253 men), aged 20 to 93 years (mean +/- standard deviation = 55.8 +/- 15.9 years) who completed the Center for Epidemiological Studies-Depression (CES-D) scale from one to eight times over 1 to 15 years. These BLSA participants later underwent high-resolution B-mode ultrasonography to assess IMT of the far wall of the common carotid artery. A subset of these participants (n = 68) underwent reassessment of IMT an average of 3.9 years later. Linear and mixed-effects regression models were adjusted for sex, race, education, systolic blood pressure, low-density lipoprotein cholesterol, body mass index, diabetes, smoking, and antihypertensive, lipid-lowering, and antidepressant medications. We found no relation between trajectory of depressive symptoms or history of significant depressive symptoms and future carotid IMT. There was also no evidence for longitudinal covariation of depressive symptoms and IMT over time. Additional analyses similarly revealed a lack of significant associations. There is no association between depressive symptoms and carotid IMT in the present sample of healthy community-dwelling volunteers.