Sleep disturbances and change in multiple cognitive domains among older adults: a multicenter study of five Nordic cohorts.

STUDY OBJECTIVES: We examined and compared cross-sectional and longitudinal associations between self-reported sleep disturbances and various cognitive domains in five separate Nordic European longitudinal aging studies (baseline N = 5631, mean age = 77.7, mean follow-up = 4.16 years). METHODS: Comparable sleep parameters across studies included reduced sleep duration/quality, insomnia symptoms (sleep latency, waking up at night, and early awakenings), short and long sleep duration, and daytime napping. The cognitive domains were episodic memory, verbal fluency, perceptual speed, executive functioning, and global cognition (aggregated measure). A series of mixed linear models were run separately in each study and then compared to assess the level and rate of change in cognitive functioning across each sleep disturbance parameter. Models were adjusted for age, sex, education, hypnotic usage, depressive symptoms, lifestyle factors, cardiovascular, and metabolic conditions. By using a coordinated analytic approach, comparable construct-level measurements were generated, and results from identical statistical models were qualitatively compared across studies. RESULTS: While the pattern of statistically significant results varied across studies, subjective sleep disturbances were consistently associated with worse cognition and steeper cognitive decline. Insomnia symptoms were associated with poorer episodic memory and participants sleeping less or more than 7-8 hours had a steeper decline in perceptual speed. In addition, daytime napping (>2 hours) was cross-sectionally and longitudinally associated with all examined cognitive domains. Most observed associations were study-specific (except for daytime napping), and a majority of association estimates remained significant after adjusting for covariates. CONCLUSION: This rigorous multicenter investigation further supports the importance of sleep disturbance, including insomnia, long and short sleep duration, and daytime napping on baseline cognitive functioning and rate of change among older adults. These sleep factors may be targeted in future lifestyle interventions to reduce cognitive decline.

Dissociating memory and executive function impairment through temporal features in a word list verbal learning task.

The Rey Auditory Verbal Learning Test (RAVLT) is an established verbal learning test commonly used to quantify memory impairments due to Alzheimer's Disease (AD) both at a clinical dementia stage or prodromal stage of mild cognitive impairment (MCI). Focal memory impairment-as quantified e.g. by the RAVLT-at an MCI stage is referred to as amnestic MCI (aMCI) and is often regarded as the cognitive phenotype of prodromal AD. However, recent findings suggest that not only learning and memory but also other cognitive domains, especially executive functions (EF) and processing speed (PS), influence verbal learning performance. This research investigates whether additional temporal features extracted from audio recordings from a participant's RAVLT response can better dissociate memory and EF in such tasks and eventually help to better describe MCI subtypes. 675 age-matched participants from the H70 Swedish birth cohort were included in this analysis; 68 participants were classified as MCI (33 aMCI and 35 due to executive impairment). RAVLT performances were recorded and temporal features extracted. Novel temporal features were correlated with established neuropsychological tests measuring EF and PS. Lastly, the downstream diagnostic potential of temporal features was estimated using group differences and a machine learning (ML) classification scenario. Temporal features correlated moderately with measures of EF and PS. Performance of an ML classifier could be improved by adding temporal features to traditional counts. We conclude that RAVLT temporal features are in general related to EF and that they might be capable of dissociating memory and EF in a word list learning task.

Hearing Loss and Cognitive Function in Early Old Age: Comparing Subjective and Objective Hearing Measures.

INTRODUCTION: Population-based research has consistently shown that people with hearing loss are at greater risk of cognitive impairment. We aimed to explore the cross-sectional association of both subjective and objective hearing measures with global and domain-specific cognitive function. We also examined the influence of hearing aid use on the relationship. METHODS: A population-based sample (n = 1,105, 52% women) of 70-year-olds that were representative of the inhabitants of the city of Gothenburg, Sweden completed a detailed cognitive examination, pure-tone audiometry, and a questionnaire regarding perceived hearing problems. A subsample (n = 247, 52% women) also completed a test of speech-recognition-in-noise (SPRIN). Multiple linear regression analyses were conducted to explore the association of hearing with cognitive function, adjusting for sex, education, cardiovascular factors, and tinnitus. RESULTS: Global cognitive function was independently associated with the better ear pure-tone average across 0.5-4 kHz (PTA4, ß = -0.13, 95% CI, -0.18, -0.07), the better ear SPRIN score (ß = 0.30, 95% CI, 0.19, 0.40), but not with the self-reported hearing measure (ß = -0.02, 95% CI, -0.07, 0.03). Both verbally loaded and nonverbally loaded tasks, testing a variety of cognitive domains, contributed to the association. Hearing aid users had better global cognitive function than nonusers with equivalent hearing ability. The difference was only significant in the mild hearing loss category. DISCUSSION: In a population-based sample of 70-year-old persons without dementia, poorer hearing was associated with poorer global and domain-specific cognitive function, but only when hearing function was measured objectively and not when self-reported. The speech-in-noise measure showed the strongest association. This highlights the importance of including standardized hearing tests and controlling for hearing status in epidemiological geriatric research. More research is needed on the role that hearing aid use plays in relation to age-related cognitive declines.

Screening for Mild Cognitive Impairment Using a Machine Learning Classifier and the Remote Speech Biomarker for Cognition: Evidence from Two Clinically Relevant Cohorts.

BACKGROUND: Modern prodromal Alzheimer's disease (AD) clinical trials might extend outreach to a general population, causing high screen-out rates and thereby increasing study time and costs. Thus, screening tools that cost-effectively detect mild cognitive impairment (MCI) at scale are needed. OBJECTIVE: Develop a screening algorithm that can differentiate between healthy and MCI participants in different clinically relevant populations. METHODS: Two screening algorithms based on the remote ki:e speech biomarker for cognition (ki:e SB-C) were designed on a Dutch memory clinic cohort (N = 121) and a Swedish birth cohort (N = 404). MCI classification was each evaluated on the training cohort as well as on the unrelated validation cohort. RESULTS: The algorithms achieved a performance of AUC  0.73 and AUC  0.77 in the respective training cohorts and AUC  0.81 in the unseen validation cohorts. CONCLUSION: The results indicate that a ki:e SB-C based algorithm robustly detects MCI across different cohorts and languages, which has the potential to make current trials more efficient and improve future primary health care.