Sleep and markers of cardiovascular disease risk in elderly Alzheimer's caregivers

Background : Sleep has been shown to be shorter and more disturbed in Alzheimer's caregivers compared to non- caregivers, presumably due to challenges associated with caregiving. Caring for a spouse with Alzheimer's disease has also been associated with increased risk for cardiovascular disease (CVD) morbidity and mortality. The increased risk of CVD may be due to the effect that insufficient sleep (disrupted sleep or inadequate sleep duration) has on numerous physiologic processes that can stress the cardiovascular system. Objectives : This dissertation aimed to (1) assess associations of both sleep duration and efficiency with prevalence of the traditional CVD risk factors of type 2 diabetes, dyslipidemia, and hypertension; (2) investigate whether both sleep duration and efficiency were associated with morning plasma catecholamine concentrations; and (3) determine the associations of both sleep duration and disturbance with carotid intima-media thickness (CIMT) in a sample of community-dwelling elderly Alzheimer's caregivers. Methods : Participants were 126 caregivers for spouses with Alzheimer's disease who underwent sleep assessment by wrist actigraphy for 72 consecutive hours. Sleep data were averaged across the 3 days/nights; nighttime sleep and daytime napping were computed. Morning fasting blood samples were collected to determine measures of blood lipids, glucose, and catecholamines (dopamine, epinephrine and norepinephrine); the average of three resting blood pressure measurements was used to estimate mean resting blood pressure; and carotid artery ultrasound was used to measure CIMT. All collections, measurements and assessments were conducted in participants' homes. Results : Analyses indicate that in an elderly sample of Alzheimer's caregivers, sleep parameters were not significantly associated with prevalent type 2 diabetes, dyslipidemia, or hypertension. However, greater nighttime sleep efficiency and duration were associated with increased morning plasma catecholamine concentrations in this sample of elderly Alzheimer's caregivers. In addition, shorter naps and more disturbed nighttime sleep were associated with increased CIMT. Conclusions : While findings presented suggest that sleep was not significantly associated with prevalent metabolic conditions, sufficient nighttime sleep and/or napping were associated with increased morning plasma catecholamine concentrations and reduced subclinical carotid atherosclerosis in a sample of elderly Alzheimer's caregivers. These analyses contribute to understanding associations between sleep and markers of cardiovascular disease risk in elderly caregivers. Further research on elderly adults with non-invasive, objective sleep measures is recommende