Association of sleep behaviors with white matter hyperintensities and microstructural injury: a cross-sectional and longitudinal analysis of 26,354 participants

Sleep Characteristics and Risk of Stroke and Dementia: An Observational and Mendelian Randomization Study

BACKGROUND AND OBJECTIVES

Sleep disturbances are implicated as risk factors of both stroke and dementia. However, whether these associations are causal and whether treatment of sleep disorders could reduce stroke and dementia risk remain uncertain. We aimed to evaluate associations and ascertain causal relationships between sleep characteristics and stroke/dementia risk and MRI markers of small vessel disease (SVD).

METHODS

We used data sets from a multicenter population-based study and summary statistics from genome-wide association studies (GWASs) of sleep characteristics and outcomes. We analyzed 502,383 UK Biobank participants with self-reported sleep measurements, including sleep duration, insomnia, chronotype, napping, daytime dozing, and snoring. In observational analyses, the primary outcomes were incident stroke, dementia, and their subtypes, alongside SVD markers. Hazard ratios (HRs) and odds ratios (ORs) were adjusted for age, sex, and ethnicity, and additional vascular risk factors. In Mendelian randomization (MR) analyses, ORs or risk ratios are reported for the association of each genetic score with clinical or MRI end points.

RESULTS

Among 502,383 participants (mean [SD] age, 56.5 [8.1] years; 54.4% female), there were 7,668 cases of all-cause dementia and 10,334 strokes. In longitudinal analyses, after controlling for cardiovascular risk factors, participants with insomnia, daytime napping, and dozing were associated with increased risk of any stroke (HR 1.05, 95% CI 1.01-1.11, p = 8.53 × 10-3; HR 1.09, 95% CI 1.05-1.14, p = 3.20 × 10-5; HR 1.19, 95% CI 1.08-1.32, p = 4.89 × 10-4, respectively). Almost all sleep measures were associated with dementia risk (all p < 0.001, except insomnia). Cross-sectional analyses identified associations between napping, snoring, and MRI markers of SVD (all p < 0.001). MR analyses supported a causal link between genetically predicted insomnia and increased stroke risk (OR 1.31, 95% CI 1.13-1.51, p = 0.00072), but not with dementia or SVD markers.

DISCUSSION

We found that multiple sleep measures predicted future risk of stroke and dementia, but these associations were attenuated after controlling for cardiovascular risk factors and were absent in MR analyses for Alzheimer disease. This suggests possible confounding or reverse causation, implying caution before proposing sleep disorder modifications for dementia treatment.

Cerebrovascular pathology mediates associations between hypoxemia during rapid eye movement sleep and medial temporal lobe structure and function in older adults

Obstructive sleep apnea (OSA) is common in older adults and is associated with medial temporal lobe (MTL) degeneration and memory decline in aging and Alzheimer's disease (AD). However, the underlying mechanisms linking OSA to MTL degeneration and impaired memory remains unclear. By combining magnetic resonance imaging (MRI) assessments of cerebrovascular pathology and MTL structure with clinical polysomnography and assessment of overnight emotional memory retention in older adults at risk for AD, cerebrovascular pathology in fronto-parietal brain regions was shown to statistically mediate the relationship between OSA-related hypoxemia, particularly during rapid eye movement (REM) sleep, and entorhinal cortical thickness. Reduced entorhinal cortical thickness was, in turn, associated with impaired overnight retention in mnemonic discrimination ability across emotional valences for high similarity lures. These findings identify cerebrovascular pathology as a contributing mechanism linking hypoxemia to MTL degeneration and impaired sleep-dependent memory in older adults.

Self-reported childhood adversity, unhealthy lifestyle and risk of new-onset chronic kidney disease in later life: A prospective cohort study

BACKGROUND

The prospective relation of childhood adversity with the risk of chronic kidney disease (CKD) remains unclear. We aimed to investigate the association of childhood adversity with new-onset CKD and examine the potential modifications by unhealthy lifestyle on this association.

METHODS

A total of 115,453 adults without prior CKD at baseline were included from UK Biobank (2006-2010). Childhood adversity was retrospectively evaluated through online Childhood Trauma Screener in 2016. Six common lifestyle factors including smoking, body mass index, sleep, diet, physical activity and alcohol consumption, were combined into an unhealthy lifestyle score. New-onset CKD was the primary outcome.

RESULT

The average age of participants in the study was 55.3 (SD, 7.7) years, and 39.3% of them were male. During a median follow-up duration of 14.1 years, 1905 participants developed new-onset CKD. Childhood adversity was significantly positively related with the risk of new-onset CKD in dose-response pattern. Each additional type of childhood adversity was associated with a 12% increment in the risk of developing CKD (adjusted hazard ratio (HR)1.12; 95% CI 1.08, 1.16). Among participants with high unhealthy lifestyle score, those with 4-5 types of childhood adversity increased the 1.73-fold risk of incident CKD (95% CI 1.17, 2.54) compared with those free of any childhood adversity. However, no statistically significant interaction was observed between unhealthy lifestyle and childhood adversity for new-onset CKD (P interaction = 0.734).

CONCLUSIONS

Childhood adversity was significantly associated with an increased risk of new-onset CKD in a dose-response pattern regardless of unhealthy lifestyle.

Association of socioeconomic deprivation with sleep health in patients with type 2 diabetes

AIMS

To investigate the association between socioeconomic deprivation and indicators of sleep health among patients with type 2 diabetes mellitus (T2DM), and additionally, to examine whether socioeconomic deprivation is associated with higher glycated haemoglobin (HbA1c) levels in these patients.

MATERIALS AND METHODS

We analysed data from the UK Biobank, consisting of 17 206 participants with T2DM, to explore the relationship between socioeconomic deprivation, self-reported indicators of sleep health, and HbA1c levels. Socioeconomic deprivation was assessed using the Townsend deprivation index. Participants were divided into two groups: low socioeconomic deprivation (n = 8604; reference group) and high socioeconomic deprivation (n = 8602). Logistic regression models were employed, adjusting for covariates such as body mass index (BMI), age, and biological sex.

RESULTS

Patients with high socioeconomic deprivation had higher odds of reporting usual difficulties falling asleep or sleeping through the night (adjusted odds ratio 1.20, 95% confidence interval [CI] 1.12, 1.28), and they were more likely to use at least one hypnotic medication (adjusted odds ratio 1.41, 95% CI 1.09, 1.84). They also had higher odds of reporting snoring and difficulties staying awake during the daytime (adjusted odds ratio 1.09, 95% CI 1.01, 1.18), as well as experiencing short sleep duration (defined as <6 hours of sleep per day; adjusted odds ratio 1.69, 95% CI 1.50, 1.91). Moreover, patients with high socioeconomic deprivation had increased odds of experiencing comorbid sleep problems (P ≤ 0.001). Finally, high socioeconomic deprivation was associated with a 0.1% higher HbA1c level (P < 0.001). Controlling for indicators of poor sleep health did not alter the strength of this association.

CONCLUSIONS

Socioeconomic deprivation may represent a risk factor for poor sleep health in patients with T2DM.