Sleep disturbances and disorders in the memory clinic: Self-report, actigraphy, and polysomnography

Abstract

BackgroundSleep disturbances are common in dementia but rarely studied in memory clinics.ObjectiveIn a memory clinic setting we aimed to (1) identify rates of obstructive sleep apnea (OSA), abnormal sleep duration, circadian phase shift, insomnia, poor sleep quality, and REM sleep behavior disorder (RBD); (2) assess concordance between self-reported and actigraphy-derived measures; investigate associations between sleep disturbances; and (3) neuropsychological performance and (4) cognitive status.MethodsAdults over 50 at a memory clinic between 2009-2024 were included. OSA was assessed via polysomnography and prior history. Sleep duration and circadian phase were measured by self-report and actigraphy. Self-report questionnaires evaluated insomnia, sleep quality, and RBD. Global cognition, processing speed, memory, and executive function were assessed. Analysis of Covariance and multinomial logistic regression examined the impact of OSA, sleep duration, insomnia, and sleep quality on cognition and cognitive status.Results1234 participants (Mage 67.2, 46%M) were included. 75.3% had OSA, while 12.7% were previously diagnosed. Insomnia affected 12.0%, 54.3% had poor sleep quality, and 14.2% endorsed RBD symptoms. Self-reported short (30.5%) and long (10.2%) sleep exceeded actigraphy rates (8.5% and 5.1%) with poor concordance between measures. OSA was linked to impaired global cognition and memory (p < 0.05). Prolonged sleep predicted deficits in global cognition, processing speed, memory, and executive function and a higher risk of aMCI (all p < 0.05). Poor sleep quality was linked to better memory (p < 0.05).ConclusionsDespite discrepancies between self-reported and objective prevalence rates, sleep disturbances are highly prevalent in memory clinics and impact cognition, necessitating further examination.

Keywords: Alzheimer's disease; REM sleep behavior disorder; aging; circadian rhythm; dementia; mild cognitive impairment; sleep apnea.

Figure 1.

Breakdown of participants, showing sample size for self-reported OSA, polysomnography, actigraphy, ISI questionnaire, PSQI questionnaire, and RBD questionnaire. OSA: obstructive sleep apnea; ISI: insomnia severity index; PSQI: Pittsburgh Sleep Quality Index; RBD: REM sleep behavior disorder.

Figure 2.

Histograms illustrating the percentage of older adults at-risk of dementia for a) obstructive sleep apnea (OSA), b) short and long sleep duration, and c) delayed and advanced sleep phase. a) For OSA, 12.7% had a prior diagnosis of OSA before attending the memory clinic and upon polysomnography (PSG) 75.3% had OSA. More specifically, 35% have mild, 24.9% have moderate, and 15.5% have severe OSA. b) For long and short sleep durations, self-report revealed 30.5% have short sleep duration (<6hours) and 10.2% have long sleep duration (>9hours). Actigraphy data suggested lower rates of 8.5% with short and 5.1% with long sleep duration. c) For sleep phase, based on self-report 13.0% had delayed sleep phase while 7.4% had advanced sleep phase. Aligned with actigraphy data which revealed 15.2% with delayed and 4.2% with advanced sleep phase.

Figure 3.

Histograms illustrating percentage of older adults attending memory clinics with a) insomnia symptoms, b) poor sleep quality, and c) REM sleep behavior disorder. a) For insomnia symptoms, 25.7% had subthreshold, 10.6% had moderate, and 1.4% had severe insomnia symptoms. b) For subjective sleep quality, 54.3% had poor sleep quality, c) for REM sleep behavior disorder, 14.2% met cut-off (≥5) on the REM sleep behavior disorder screening questionnaire for REM sleep behavior disorder.