Associations of sleep duration and daytime sleepiness with plasma amyloid beta and cognitive performance in cognitively unimpaired, middle-aged and older African Americans

Lifestyle factors and plasma biomarkers of Alzheimer's disease: A narrative review

Alzheimer's disease (AD) is a neurodegenerative disorder characterised by amyloid-β (Aβ), tau hyperphosphorylation and neurodegeneration. Blood-based biomarkers are emerging as a minimally invasive tool for disease detection and monitoring. This review depicts the relationships between modifiable lifestyle factors (nutrition, physical activity (PA), sleep, alcohol consumption, smoking, and social isolation) and plasma biomarkers of AD: Aβ42, Aβ40, Aβ42/40, phosphorylated tau, total tau, neurofilament light chain (NfL) and glial fibrillary acidic protein. Limited evidence suggests that better nutrition is associated with favourable AD plasma biomarker profiles and that PA is associated with less plasma NfL and Aβ, whilst poor sleep is associated with elevated plasma Aβ. However, lack of data and inconsistent findings highlight the need for further investigation to substantiate or refute these trends. Moreover, future research should include the analysis of lifestyle on plasma biomarkers according to gender, metabolic health and APOE status. Considering the growing emphasis on modifiable lifestyle factors for preventing and delaying dementia onset further investigation is justified.

Associations among sleep quality, sleep duration, and Alzheimer's disease biomarkers: A systematic review and meta-analysis

INTRODUCTION

Although sleep disturbances are widely recognized as risk factors for cognitive decline and Alzheimer's disease (AD), their influence on AD biomarkers remains unclear. This study aimed to clarify whether sleep quality or sleep duration affect amyloid beta (Aβ) and tau levels in plasma, cerebrospinal fluid (CSF), and positron emission tomography (PET) in non-demented populations.

METHODS

PubMed, Web of Science, and Embase were systematically searched up to February 2025.

RESULTS

In total, 30 studies were included comprising 14,997 subjects. Individuals with poor sleep quality exhibited greater PET Aβ burden and higher Aβ42 levels in plasma than those with good sleep quality. Shorter sleep duration was associated with higher Aβ burden on PET. However, no association between either sleep quality or sleep duration and tau levels was found.

DISCUSSION

Sleep may be a modifiable marker of early AD management by modulating Aβ levels.

HIGHLIGHTS

lPoor sleep quality and shorter sleep duration were significantly associated with higher amyloid beta (Aβ) burden detected by positron emission tomography (PET) in non-demented populations. Poor sleep quality was also associated with elevated Aβ42 levels in plasma. lNo significant associations were found between sleep quality or sleep duration and tau levels in plasma, cerebrospinal fluid, or PET. lInterventions targeting sleep could serve as a viable and low-cost prevention strategy for early management of Alzheimer's disease.

Interactions among neighborhood conditions, sleep quality, and episodic memory across the adult lifespan

OBJECTIVES

On average, adults racialized as non-Hispanic Black and Hispanic sleep more poorly than adults racialized as non-Hispanic White (hereafter, Black, Hispanic, White), but associations between factors that may moderate sleep-memory associations in these groups, such as neighborhood conditions, are unclear. Poorer neighborhood conditions (e.g. lower neighborhood cohesion) may be negatively associated with sleep quality and multiplicatively influence sleep-memory associations. We hypothesized lower ratings of neighborhood conditions would be associated with poorer sleep quality and moderate the association between sleep quality and episodic memory, especially in Black and Hispanic adults, who are disproportionately situated in poor neighborhood conditions.

DESIGN

Seven-hundred-thirty-six adults across the adult lifespan (27-89 years) were recruited from the northern Manhattan community as a part of the Offspring Study of Racial and Ethnic Disparities in Alzheimer's disease. Sleep quality was assessed using a modified version of the Pittsburgh Sleep Quality Index, and episodic memory was evaluated with the Buschke Selective Reminding Test. With multiple regression models, we measured associations between perceived neighborhood conditions and sleep quality and the interaction between sleep quality and neighborhood conditions on episodic memory stratified by racial/ethnic and gender identity groups.

RESULTS

Overall, poorer neighborhood conditions were associated with poorer sleep quality. In Black and Hispanic women, the sleep-memory association was moderated by neighborhood conditions. With more favorable neighborhood conditions, Black women showed an association between higher sleep quality and higher memory performance, and Hispanic women showed a protective effect of neighborhood (higher memory even when sleep quality was poor).

CONCLUSION

Poorer neighborhood experiences may contribute to poorer sleep quality across groups. In Black and Hispanic women, the association between sleep quality and episodic memory performance was dependent upon neighborhood conditions. These findings may inform tailored, structural level sleep interventions, aimed to improve neighborhood experiences and thereby sleep quality and episodic memory.