Insomnia and Neurocognitive Functioning in Cognitively Healthy Older Adults

Abstract

AbstractBackgroundInsomnia is the most common sleep disorder in older adults, affecting the ability to fall and stay asleep for approximately 15‐35% of aging adults (Buysse et al., 2011). Additionally, sleep fragmentation and disordered sleep are well‐established symptoms of Alzheimer’s disease (AD). Patients and their caregivers frequently find these sleep changes distressing; however, the relationship between insomnia and preclinical Alzheimer’s disease remains unclear. The purpose of the present study is to compare performance on neurocognitive measures between cognitively healthy older adults with and without clinician‐determined insomnia to assess whether insomnia acutely impacts cognitive functioning.MethodData were obtained from the National Alzheimer’s Coordinating Center (NACC) database. As part of ongoing data collection, NACC participants completed surveys and underwent a neuropsychological evaluation. Participants who were cognitively healthy at baseline, reported insomnia status, and were at least 65 years of age were included (N = 3,733). Clinicians determined the presence of insomnia (present/absent). A series of Welch’s t‐tests were used to compare insomnia status groups on demographic factors (age, educational attainment, and sex) as well as neurocognitive measures typically related to Alzheimer’s disease (animal and vegetable fluency, letter fluency, Trail‐Making Test, Benson Complex Figure delayed recall, Montreal Cognitive Assessment delayed recall).ResultPreliminary analyses of sample characteristics found evidence that individuals with insomnia were older than those without insomnia (t(784.11) = 2.046, p = 0.041). As expected, clinician‐determined insomnia was more common in men than women (χ2 (1) = 29.638, p < .001). Group comparisons indicated no cross‐sectional relationship between insomnia status and neurocognitive measures (all p >.05, all d ≤ .06).ConclusionDisordered sleep is often seen in Alzheimer’s disease, yet the nature and timing of this relationship are unclear. We found no association between insomnia status and neurocognitive performance in a large, cross‐sectional sample of healthy older adults. It is possible that sleep disturbance is not a preclinical symptom of AD but instead may emerge closer to or following AD diagnosis. Alternatively, the nature of the disordered sleep may not be related to insomnia per se but could reflect difficulty sleeping during the night and remaining awake during the day.