Association Between Informant-Reported Sleep Disturbance and Incident Dementia: An Analysis of the National Alzheimer's Coordinating Center Uniform Data Set

The effects of sleep duration on the risk of dementia incidence in short and long follow-up studies: A systematic review and meta-analysis

Sleep duration's association with future dementia could be a cause or consequence, or both. We searched electronic databases on 14th April 2023 for primary peer-reviewed, longitudinal studies examining the relationship between sleep duration and dementia with any follow-up duration. We meta-analysed studies examining brief (≤6 h/night) and extended sleep duration (≥9 h/night) separately and divided the studies into those with follow-up periods of less or more than 10 years. The quality of evidence was assessed using the Newcastle-Ottawa scale. 31 studies fulfilled the inclusion criteria. For brief sleep duration, a meta-analysis of short follow-up studies (≤10 years) found a 46 % increased risk of future dementia (relative risk [RR] - 1·46; 95 % Confidence Intervals [CIs] 1·48-1·77; I2 = 88·92 %, 6 studies). Studies with long follow-ups (>10 years) did not show a significantly increased risk (RR - 1·12; 0·95-1·29; I2 = 65·91 %; 5 studies). For extended sleep duration, a meta-analysis of short and long follow-up studies reported an increased risk of dementia (respectively RR - 2·20; 1·11-3·3; I2 = 94·17 %; 4 studies and RR - 1·74; 1·30-2·18; I2 = 86·56 %; 4 studies). Our findings suggest that brief sleep duration might be a prodromal symptom but not a risk factor of dementia. Extended sleep duration may be a risk factor. However, our results had high heterogeneity limiting external validity and generalisability.

Association of education attainment, smoking status, and alcohol use disorder with dementia risk in older adults: a longitudinal observational study

BACKGROUND

Previous research on the risk of dementia associated with education attainment, smoking status, and alcohol use disorder (AUD) has yielded inconsistent results, indicating potential heterogeneous treatment effects (HTEs) of these factors on dementia risk. Thus, this study aimed to identify the important variables that may contribute to HTEs of these factors in older adults.

METHODS

Using 2005-2021 data from the National Alzheimer's Coordinating Center (NACC), we included older adults (≥ 65 years) with normal cognition at the first visit. The exposure of interest included college education or above, current smoking, and AUD and the outcome was all-cause dementia. We applied doubly robust learning to estimate risk differences (RD) and 95% confidence intervals (CI) between exposed and unexposed groups in the overall cohort and subgroups identified through a decision tree model.

RESULTS

Of 10,062 participants included, 929 developed all-cause dementia over a median 4.4-year follow-up. College education or above was associated with a lower risk of all-cause dementia in the overall population (RD, -1.5%; 95%CI, -2.8 to -0.3), especially among the subpopulations without hypertension, regardless of the APOE4 status. Current smoking was not related to increased dementia risk overall (2.8%; -1.5 to 7.2) but was significantly associated with increased dementia risk among men with (21.1%, 3.1 to 39.1) and without (8.4%, 0.9 to 15.8) cerebrovascular disease. AUD was not related to increased dementia risk overall (2.0%; -7.7 to 11.7) but was significantly associated with increased dementia risk among men with neuropsychiatric disorders (31.5%; 7.4 to 55.7).

CONCLUSIONS

Our studies identified important factors contributing to HTEs of education, smoking, and AUD on risk of all-cause dementia, suggesting an individualized approach is needed to address dementia disparities.

Sleep characteristics and risk of Alzheimer's disease: a systematic review and meta-analysis of longitudinal studies

BACKGROUND

Alzheimer's disease (AD) is on the rise in our aging society, making it crucial to identify additional risk factors to mitigate its increasing incidence. This systematic review and meta-analysis aimed to provide updated evidence regarding the association between sleep and AD.

METHODS

We conducted a comprehensive search of MEDLINE, EMBASE, and Web of Science databases from inception to July 2023 to identify longitudinal studies. Adjusted relative risks were pooled for each sleep characteristic, and a dose-response analysis was performed specifically for sleep duration.

RESULTS

A total of 15,278 records were initially retrieved, and after screening, 35 records were ultimately included in the final analysis. The results showed that insomnia (RR, 1.43; 95%CI, 1.17-1.74), sleep-disordered breathing (RR, 1.22; 95%CI, 1.07-1.39), as well as other sleep problems, including sleep fragmentation and sleep-related movement disorders, were associated with a higher risk of developing AD, while daytime napping or excessive daytime sleepiness (RR, 1.18; 95%CI, 1.00-1.40) only exhibited a trend toward a higher risk of AD development. Furthermore, our analysis revealed a significant association between self-reported sleep problems (RR, 1.34; 95%CI, 1.26-1.42) and the incidence of AD, whereas this association was not observed with sleep problems detected by objective measurements (RR, 1.14; 95%CI, 0.99-1.31). Moreover, both quite short sleep duration (< 4 h) and long duration (> 8 h) were identified as potential risk factors for AD.

CONCLUSIONS

Our study found the association between various types of sleep problems and an increased risk of AD development. However, these findings should be further validated through additional objective device-based assessments. Additional investigation is required to establish a definitive causal connection between sleep problems and AD.

Longitudinal Associations Between Mild Behavioral Impairment, Sleep Disturbance, and Progression to Dementia

Background

Clinical guidelines recommend incorporating non-cognitive markers like mild behavioral impairment (MBI) and sleep disturbance (SD) into dementia screening to improve detection.

Objective

We investigated the longitudinal associations between MBI, SD, and incident dementia.

Methods

Participant data were from the National Alzheimer's Coordinating Center in the United States. MBI was derived from the Neuropsychiatric Inventory Questionnaire (NPI-Q) using a published algorithm. SD was determined using the NPI-Q nighttime behaviors item. Cox proportional hazard regressions with time-dependant variables for MBI, SD, and cognitive diagnosis were used to model associations between baseline 1) MBI and incident SD (n = 11,277); 2) SD and incident MBI (n = 10,535); 3) MBI with concurrent SD and incident dementia (n = 13,544); and 4) MBI without concurrent SD and incident dementia (n = 11,921). Models were adjusted for first-visit age, sex, education, cognitive diagnosis, race, and for multiple comparisons using the Benjamini-Hochberg method.

Results

The rate of developing SD was 3.1-fold higher in older adults with MBI at baseline compared to those without MBI (95% CI: 2.8-3.3). The rate of developing MBI was 1.5-fold higher in older adults with baseline SD than those without SD (95% CI: 1.3-1.8). The rate of developing dementia was 2.2-fold greater in older adults with both MBI and SD, as opposed to SD alone (95% CI:1.9-2.6).

Conclusions

There is a bidirectional relationship between MBI and SD. Older adults with SD develop dementia at higher rates when co-occurring with MBI. Future studies should explore the mechanisms underlying these relationships, and dementia screening may be improved by assessing for both MBI and SD.

Familial natural short sleep mutations reduce Alzheimer pathology in mice

Although numerous studies have demonstrated that poor sleep increases the development of AD, direct evidence elucidating the benefits of good sleep on the AD pathogenesis is lacking. Familial Natural Short Sleepers (FNSS) are genetically wired to have lifelong reduction in nightly sleep duration without evident consequence on cognitive demise, implying that they may have better sleep quality. Here we investigated two FNSS mutations, DEC2-P384R and Npsr1-Y206H, on the development of tau and amyloid pathology in AD-like mouse models. We found that the development of tau pathology is attenuated in the hippocampus of tau mice carrying FNSS mutations. We also found that DEC2-P384R;5XFAD and female Npsr1-Y206H;5XFAD mice exhibit significantly less amyloid plaques than control mice at 6 months of age. Together, these results reveal that these two FNSS alleles are strong genetic modifiers of AD pathology and may confer resilience to the progression of tau pathology and amyloid plaque formation in neurodegeneration.

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Two FNSS mutations are strong genetic modifiers of AD-like pathology in mice

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Mutant DEC2 and Npsr1 reduced tau pathology in PS19 mouse model of tauopathy

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Mutant DEC2 and Npsr1 slowed down amyloid plaques in 5XFAD APP transgenic mouse model

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Efficient sleep may be an exciting therapeutic target for ameliorating AD development

Association of Sleep With Risk of Alzheimer's Disease Mortality: NIH-AARP Diet and Health Study

OBJECTIVES

Alzheimer's disease (AD) and related dementias contribute to one in three senior deaths. Lifestyle factors, including sleep, may contribute to AD risk and mortality; however, current evidence on sleep and AD mortality is mixed.

METHODS

We used data from the NIH-AARP Diet and Health Study. Sleep duration and napping were self-reported and AD death were ascertained via linkage to the National Death Index.

RESULTS

Long sleep and napping were both associated with increased AD mortality. Specifically, 9+ hr of sleep was associated with 50% increase (hazard ratio = 1.50, 95% CI = [1.17, 1.92]) in AD mortality when compared 7 to 8 hr, while napping for 1+ hr was associated with 29% increase (1.29 [1.08, 1.55]) when compared with no napping. Results appeared to be stronger in men and remained after removing AD deaths within first 5 years after baseline.

DISCUSSION

Long sleep and napping may predict higher AD mortality in the older population.