Association of Sleep Duration and Change Over Time With Imaging Biomarkers of Cerebrovascular, Amyloid, Tau, and Neurodegenerative Pathology

Long sleep duration, cognitive performance, and the moderating role of depression: A cross-sectional analysis in the Framingham Heart Study

INTRODUCTION

We investigated whether depression modified the associations between sleep duration and cognitive performance.

METHODS

We examined the associations between sleep duration and cognition in 1853 dementia-and-stroke-free participants (mean age 49.8 years, [range 27-85]; 42.7% male). Participants were categorized into four groups: no depressive symptoms, no antidepressants; depressive symptoms without antidepressant use; antidepressant use without depressive symptoms; and depressive symptoms and antidepressant use.

RESULTS

Long sleep was associated with reduced overall cognitive function (β ± standard error = -0.25 ± 0.07, p < 0.001), with strongest effects in those with depressive symptoms using (-0.74 ± 0.30, p = 0.017) and not using antidepressants (-0.60 ± 0.26, p = 0.024). Weaker but significant effects were observed in those without depressive symptoms (-0.18 ± 0.09, p = 0.044). No significant associations were observed in participants using antidepressants without depressive symptoms.

DISCUSSION

Associations between sleep duration and cognitive performance are strongest in individuals with depressive symptoms, regardless of antidepressant use. Future research should elucidate underlying mechanisms and temporal relationships.

HIGHLIGHTS

Sleeping ≥ 9 hours/night was associated with worse cognitive performance. This association was stronger among those with depression. Long sleepers were more likely to report symptoms of depression. Sleep may be a modifiable risk for cognitive decline in people with depression.

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.

Sleep Patterns and Human Brain Health

It is a widely held opinion that sleep is important for human brain health. Here we examine the evidence for this view, focusing on normal variations in sleep patterns. We discuss the functions of sleep and highlight the paradoxical implications of theories seeing sleep as an adaptive capacity versus the theory that sleep benefits clearance of metabolic waste from the brain. We also evaluate the proposition that sleep plays an active role in consolidation of memories. Finally, we review research on possible effects of chronic sleep deprivation on brain health. We find that the evidence for a causal role of sleep in human brain health is surprisingly weak relative to the amount of attention to sleep in science and society. While there are well-established associations between sleep parameters and aspects of brain health, results are generally not consistent across studies and measures, and it is not clear to what extent alterations in sleep patterns represent symptoms or causes. Especially, the proposition that long sleep (>8 hours) in general is beneficial for long-term brain health in humans seems to lack empirical support. We suggest directions for future research to establish a solid foundation of knowledge about a role of sleep in brain health based on longitudinal studies with frequent sampling, attention to individual differences, and more ecologically valid intervention studies.

Long Sleep Duration, Cognitive Performance, and the Moderating Role of Depression: A Cross-Sectional Analysis in the Framingham Heart Study

INTRODUCTION

We investigated whether depression modified the associations between sleep duration and cognitive performance.

METHODS

Multivariable linear regression models examined the associations between sleep duration and cognition in 1,853 dementia- and stroke-free participants from the Framingham Heart Study. Participants were categorized in four groups: no depressive symptoms, no antidepressants; depressive symptoms without antidepressants use; antidepressant use without depressive symptoms; both depressive symptoms and antidepressant use.

RESULTS

Long sleep was associated with reduced overall cognitive function. Strong associations between sleep duration and cognitive performance were found in individuals with depressive symptoms, regardless of antidepressant use. Weaker but significant effects were observed in those without depressive symptoms. No significant associations were observed in participants using antidepressants without depressive symptoms.

DISCUSSION

These findings provide new evidence that sleep duration may be a modifiable risk factor for cognitive decline, particularly in individuals with depressive symptoms. Future research should elucidate underlying mechanisms and temporal relationships.

Brain function assessment of acupuncture for chronic insomnia disorder with mild cognitive dysfunction based on fNIRS: protocol for a randomized controlled trial

Background

Chronic Insomnia Disorder (CID) is highly prevalent among older adults and impairs cognitive function. Insomnia accelerates the progression of mild cognitive impairment (MCI) and increases the risk of developing dementia. Acupuncture has been demonstrated in improving sleep quality and cognitive function. This study aims to explore the functional brain characteristics of CID with MCI patients and to assess the effects of acupuncture therapy using functional near-infrared spectroscopy (fNIRS).

Methods and design

This study is a single-center randomized controlled trial. Participants will be randomly assigned to the manual acupuncture group or the placebo acupuncture group for an 8-week intervention period. fNIRS data will be collected during resting test and working memory test at baseline and at end of the intervention. The primary outcome is the change of the Montreal Cognitive Assessment (MoCA) score, secondary outcomes include the change of Mini-Mental State Examination (MMSE), Insomnia Severity Index (ISI), Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder Scale (GAD-7), and Apathy Evaluation Scale-Informant (AES-I).

Discussion

The results of the study will provide insights into the effects of acupuncture on sleep quality and cognitive performance in CID with MCI patients. By utilizing fNIRS technology, we will elucidate the neural functional characteristic underlying the therapeutic benefits of acupuncture.

Clinical trial registration

https://ClinicalTrials.gov, identifier ChiCTR2300076182.

Sleep disorders and risk of alzheimer's disease: A two-way road

Substantial sleep impairment in patients with Alzheimer's disease (AD) is one of the emerging points for continued efforts to better understand the disease. Individuals without cognitive decline, an important marker of the clinical phase of AD, may show early alterations in the sleep-wake cycle. The objective of this critical narrative review is to explore the bidirectional pathophysiological correlation between sleep disturbances and Alzheimer's Disease. Specifically, it examines how the disruption of sleep homeostasis in individuals without dementia could contribute to the pathogenesis of AD, and conversely, how neurodegeneration in individuals with Alzheimer's Disease might lead to dysregulation of the sleep-wake cycle. Recent scientific results indicate that sleep disturbances, particularly those related to impaired glymphatic clearance, may act as an important mechanism associated with the genesis of Alzheimer's Disease. Additionally, amyloid deposition and tau protein hyperphosphorylation, along with astrocytic hyperactivation, appear to trigger changes in neurotransmission dynamics in areas related to sleep, which may explain the onset of sleep disturbances in individuals with AD. Disruption of sleep homeostasis appears to be a modifiable risk factor in Alzheimer's disease. Whenever possible, the use of non-pharmacological strategies becomes important in this context. From a different perspective, additional research is needed to understand and treat the dysfunction of the sleep-wake cycle in individuals already affected by AD. Early recognition and correction of sleep disturbances in this population could potentially mitigate the progression of dementia and improve the quality of life for those with AD.

Rescuing impaired hippocampal-cortical interactions and spatial reorientation learning and memory during sleep in a mouse model of Alzheimer's disease using hippocampal 40 Hz stimulation

In preclinical Alzheimer's disease (AD), spatial learning and memory is impaired. We reported similar impairments in 3xTg-AD mice on a virtual maze (VM) spatial-reorientation-task that requires using landmarks to navigate. Hippocampal (HPC)-cortical dysfunction during sleep (important for memory consolidation) is a potential mechanism for memory impairments in AD. We previously found deficits in HPC-cortical coordination during sleep coinciding with VM impairments the next day. Some forms of 40 Hz stimulation seem to clear AD pathology in mice, and improve functional connectivity in AD patients. Thus, we implanted a recording array targeting parietal cortex (PC) and HPC to assess HPC-PC coordination, and an optical fiber targeting HPC for 40 Hz or sham optogenetic stimulation in 3xTg/PV cre mice. We assessed PC delta waves (DW) and HPC sharp wave ripples (SWRs). In sham mice, SWR-DW cross-correlations were reduced, similar to 3xTg-AD mice. In 40 Hz mice, this phase-locking was rescued, as was performance on the VM. However, rescued HPC-PC coupling no longer predicted performance as in NonTg animals. Instead, DWs and SWRs independently predicted performance in 40 Hz mice. Thus, 40 Hz stimulation of HPC rescued functional interactions in the HPC-PC network, and rescued impairments in spatial navigation, but did not rescue the correlation between HPC-PC coordination during sleep and learning and memory. Together this pattern of results could inform AD treatment timing by suggesting that despite applying 40 Hz stimulation before significant tau and amyloid aggregation, pathophysiological processes led to brain changes that were not fully reversed even though cognition was recovered.

Significance Statement

One of the earliest symptoms of Alzheimer's disease (AD) is getting lost in space or experiencing deficits in spatial navigation, which involve navigation computations as well as learning and memory. We investigated cross brain region interactions supporting memory formation as a potential causative factor of impaired spatial learning and memory in AD. To assess this relationship between AD pathophysiology, brain changes, and behavioral alterations, we used a targeted approach for clearing amyloid beta and tau to rescue functional interactions in the brain. This research strongly connects brain activity patterns during sleep to tau and amyloid accumulation, and will aid in understanding the mechanisms underlying cognitive dysfunction in AD. Furthermore, the results offer insight for improving early identification and treatment strategies.

Sleep duration in midlife and old age and risk of mortality over a 48-year follow-up: The Helsinki businessmen study (HBS) cohort

OBJECTIVES

Both short and long sleep duration have been associated with increased mortality, but there are few truly long-term studies.

STUDY DESIGN

This is a cohort study of 2504 men born between 1919 and 1934. In 1974-1975 (mean age 48), participants underwent baseline clinical examinations and sleep duration assessments. A follow-up examination took place 35 years later, in 2010 (mean age 82).

MAIN OUTCOME MEASURE

All-cause mortality data from baseline and from old age were collected through to December 31, 2022.

RESULTS

At baseline, short sleep duration (≤6 h per night), normal sleep duration (>6 and ≤ 8 h), and long sleep duration (>8 h) was reported by 266, 2019 and 219 men, respectively. Men with short sleep duration had higher levels of smoking, alcohol consumption, body mass index, and poorer self-rated health than those with normal sleep duration. During the 48-year follow-up, 2287 men died. The unadjusted hazard ratio for mortality was 1.20 (95 % confidence interval [CI] 1.05-1.37) for short compared with normal sleep duration, but this association vanished after adjustments (1.01, 95 % CI 0.87-1.17). In old age, the corresponding hazard ratios were 1.41 (1.16-1.72) and 1.19 (0.94-1.51) for short sleep duration and 1.33 (1.09-1.63) and 1.31 (1.02-1.67) for long sleep duration.

CONCLUSIONS

In a comprehensive lifespan follow-up, the modestly increased mortality among men with short sleep duration in midlife was attributed to unhealthy lifestyle factors. In old age both long and short sleep duration seemed to be associated with modestly increased mortality.

CLINICALTRIALS

gov identifier for the HBS: NCT02526082.

Neuropathologic changes at age 90+ related to sleep duration 19 to 40 years earlier: The 90+ Study

INTRODUCTION

We investigated the association between sleep duration and neuropathologic changes 19 to 40 years later in oldest-old (age 90+) participants of The 90+ Study.

METHODS

Participants self-reported sleep duration and underwent neuropathologic evaluation. We categorized sleep duration as < 7, 7 to 8 = reference, > 8 hours and dichotomized neuropathologic changes as present/absent. We estimated odds ratio (OR) and 95% confidence intervals (CI) using logistic regression.

RESULTS

In 264 participants, mean age at sleep self-report was 69 years, mean age at autopsy was 98 years, and mean interval between sleep self-report and autopsy was 29 years (range: 19-40). Those reporting > 8 hours of sleep had lower likelihood of limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) inclusions (OR = 0.18; CI = 0.04-0.82) and amyloid beta deposits (OR = 0.34; 95% CI = 0.12-0.94).

DISCUSSION

Long self-reported sleep is associated with lower odds of neurodegenerative neuropathologic changes 19 to 40 years later in the oldest-old, suggesting a potential role of sleep in accumulation of dementia-related neuropathologies.

HIGHLIGHTS

Association of self-reported sleep with non-Alzheimer's disease neuropathologic changes has not been explored. Whether sleep duration is related to dementia neuropathologic changes decades later is unclear. Long self-reported sleep is associated with lower odds of Alzheimer's disease neuropathologic change 19 to 40 years later in the oldest-old. Long self-reported sleep is associated with lower odds of limbic-predominant age-related TDP-43 encephalopathy neuropathologic change 19 to 40 years later in the oldest-old.