Sex differences in the effects of sleep disorders on cognitive dysfunction

Deciphering the impairment of perimenopausal insomnia on visual search from a neurocognitive processing perspective

STUDY OBJECTIVES

Perimenopausal insomnia (PMI) is associated with observable performance impairments in visual search tasks. This study examines how various cognitive processing stages contribute to search performance delays in PMI compared to healthy controls (HCs).

METHODS

We recruited 76 participants diagnosed with PMI and 63 HCs. Event-related potentials (ERPs) were recorded as participants engaged in a visual search task, reporting the orientation of a color popout target within an array of ellipses. We analyzed group differences in behavioral performance and ERP components across cognitive processing stages.

RESULTS

Compared to HCs, PMI patients exhibited behavioral response delays, although accuracy was not different between groups. Electrophysiological analyses revealed group differences across several ERP components. Firstly, the N1 component's amplitude increased bilaterally, suggesting enhanced visual sensory processing. Secondly, a slower and smaller N2pc indicated reduced attentional orienting. Thirdly, a decreased sustained posterior-contralateral negativity amplitude pointed to deficits in target discrimination. Fourthly, an increased amplitude of the stimulus-locked lateralized readiness potential (LRP), with unchanged latency, suggested heightened neural inputs for maintaining motor initiation speed. Fifthly, prolonged response-locked LRP latency indicated slower motor execution. Finally, these changes in ERP components, along with significant correlations between LRP components and insomnia symptoms, suggest potential neural biomarkers for PMI.

CONCLUSIONS

Our findings provide high-temporal-resolution insights into the neurocognitive disruptions associated with PMI, highlighting how sleep disturbances affect cognitive processing in visual tasks. These insights enhance our understanding of PMI and contribute to discussions on neural mechanisms driving behavioral performance in various conditions.

Antioxidants and the risk of sleep disorders: results from NHANES and two-sample Mendelian randomization study

Background

Sleep disorders have emerged as a major public health concern. Observational research indicates that antioxidants might mitigate the risk of sleep disturbances, yet the causal relationship remains uncertain.

Materials and methods

This study utilized data from the National Health and Nutrition Examination Survey (NHANES) spanning 2011 to 2018, focusing on adults who reported sleep disorders. The analysis included 25,178 American adults. We examined the association between the Composite Dietary Antioxidant Index (CDAI) and the prevalence of sleep disorders. Additionally, a two-sample Mendelian randomization analysis was conducted to explore the potential causal link between CDAI and the risk of sleep disorders.

Results

Analysis of data from the 2011-2018 NHANES survey revealed a significant negative association between CDAI and sleep disorders (OR = 0.854, 95% CI 0.821-0.888, P < 0.001). A multivariable logistic regression model showed that each unit increase in CDAI corresponded to a 14.6% reduction in sleep disorder risk, exhibiting a nonlinear trend where the risk decreased until reaching the inflection point of -0.134. Additionally, MR analysis demonstrated that genetically determined selenium reduces the risk of OSA (OR = 0.992, 95% CI 0.860-0.989, P = 0.023). Furthermore, vitamin E (γ-tocopherol) and vitamin C were protective against sleep-wake disorders (OR = 0.016, 95% CI 0.001-0.674, P = 0.03) and (OR = 0.049, 95% CI 0.007-0.346, P = 0.002), respectively.

Conclusion

Dietary antioxidants may help prevent sleep disorders. However, further studies are required to clarify the pathways through which antioxidants exert this protective effect.

Association of sleep quality with cognitive dysfunction in middle-aged and elderly adults: a cross-sectional study in China

Objectives

Sleep is an indispensable part of human health, which can help us to restore physical strength, enhance immunity and maintain nervous system stability. The relationship between sleep quality and cognitive dysfunction is unclear, especially at the community population level. This study aims to explore the association between sleep quality and cognitive dysfunction.

Methods

A total of 5,224 community residents were enrolled in this cross-sectional study. Cognitive function was assessed by the Mini-Mental State Examination (MMSE). Sleep quality was assessed by the multidimensional sleep questionnaire. Multivariate logistic regression was used to analyze the association between sleep quality and cognitive dysfunction. The adjusted models took into account relevant demographic, clinical, and sleep variables.

Results

A total of 3,106 participants were enrolled in this study, of whom 463 (15%) had cognitive dysfunction. Total sleep duration, staying up, sleep latency, number of awakenings, and history of sleep medications were associated with cognitive dysfunction in unadjusted models, and these effects were consistent after adjustment. First, those who slept 6-7.9 h per day (OR = 0.57, 95% CI 0.40 to 0.80, p = 0.001) had a lower risk for cognitive dysfunction compared to those who slept less than 6 h per day. Second, participants who stayed up more than 10 times over the 3 months (OR = 1.90, 95% CI 1.20 to 3.00, p = 0.006) were more likely to suffer cognitive dysfunction than those who never stayed up. Third, we also found that participants with sleep latencies of 16-30 min were less likely to experience cognitive dysfunction than those with sleep latencies of less than 16 min after adjusting confounders (OR = 0.33, 95% CI 0.23 to 0.47, p < 0.001). Fourth, participants who woke up once (OR = 1.65, 95% CI 1.19 to 2.30, p = 0.003) and three or more times (OR = 2.34, 95% CI 1.25 to 4.36, p = 0.008) after falling asleep had a higher risk than those who did not wake up at night. Last, participants taking sleep medication (OR = 2.97, 95% CI 1.19 to 7.45, p = 0.020) were more vulnerable to cognitive dysfunction, relative to participants without taking any medications.

Conclusion

Our results suggest that after adjustment for potential confounding variables, poor sleep quality is associated with cognitive dysfunction.

SGLT2 inhibition, circulating proteins, and insomnia: A mendelian randomization study

BACKGROUND

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) initially emerged as oral antidiabetic medication but were subsequently discovered to exhibit pleiotropic actions. Insomnia is a prevalent and debilitating sleep disorder. To date, the causality between SGLT2 inhibitors and insomnia remains unclear. This study aims to evaluate the causality between SGLT2 inhibitors and insomnia and identify potential plasma protein mediators.

METHODS

Using a two-sample Mendelian Randomization (MR) analysis, we estimated the causality of SGLT2 inhibition on insomnia and sleep duration. Additionally, employing a two-step and proteome-wide MR analysis, we evaluated the causal link of SGLT2 inhibition on 4907 circulating proteins and the causality of SGLT2 inhibition-driven plasma proteins on insomnia. We applied a false discovery rate (FDR) correction for multiple comparisons. Furthermore, mediation analyses were used to identify plasma proteins that mediate the effects of SGLT2 inhibition on insomnia.

RESULTS

SGLT2 inhibition was negatively correlated with insomnia (odds ratio [OR] = 0.791, 95 % confidence interval [CI] [0.715, 0.876], P = 5.579*10^-6) and positively correlated with sleep duration (β = 0.186, 95 % CI [0.059, 0.314], P = 0.004). Among the 4907 circulating proteins, diadenosine tetraphosphatase (Ap4A) was identified as being linked to both SGLT2 inhibition and insomnia. Mediation analysis indicated that the effect of SGLT2 inhibition on insomnia partially operates through Ap4A (β = -0.018, 95 % CI [-0.036, -0.005], P = 0.023), with a mediation proportion of 7.7 %.

CONCLUSION

The study indicated a causality between SGLT2 inhibition and insomnia, with plasma Ap4A potentially serving as a mediator.

Older adults at greater risk for Alzheimer's disease show stronger associations between sleep apnea severity in REM sleep and verbal memory

BACKGROUND

Obstructive sleep apnea (OSA) increases risk for cognitive decline and Alzheimer's disease (AD). While the underlying mechanisms remain unclear, hypoxemia during OSA has been implicated in cognitive impairment. OSA during rapid eye movement (REM) sleep is usually more severe than in non-rapid eye movement (NREM) sleep, but the relative effect of oxyhemoglobin desaturation during REM versus NREM sleep on memory is not completely characterized. Here, we examined the impact of OSA, as well as the moderating effects of AD risk factors, on verbal memory in a sample of middle-aged and older adults with heightened AD risk.

METHODS

Eighty-one adults (mean age:61.7 ± 6.0 years, 62% females, 32% apolipoprotein E ε4 allele (APOE4) carriers, and 70% with parental history of AD) underwent clinical polysomnography including assessment of OSA. OSA features were derived in total, NREM, and REM sleep. REM-NREM ratios of OSA features were also calculated. Verbal memory was assessed with the Rey Auditory Verbal Learning Test (RAVLT). Multiple regression models evaluated the relationships between OSA features and RAVLT scores while adjusting for sex, age, time between assessments, education years, body mass index (BMI), and APOE4 status or parental history of AD. The significant main effects of OSA features on RAVLT performance and the moderating effects of AD risk factors (i.e., sex, age, APOE4 status, and parental history of AD) were examined.

RESULTS

Apnea-hypopnea index (AHI), respiratory disturbance index (RDI), and oxyhemoglobin desaturation index (ODI) during REM sleep were negatively associated with RAVLT total learning and long-delay recall. Further, greater REM-NREM ratios of AHI, RDI, and ODI (i.e., more events in REM than NREM) were related to worse total learning and recall. We found specifically that the negative association between REM ODI and total learning was driven by adults 60 + years old. In addition, the negative relationships between REM-NREM ODI ratio and total learning, and REM-NREM RDI ratio and long-delay recall were driven by APOE4 carriers.

CONCLUSION

Greater OSA severity, particularly during REM sleep, negatively affects verbal memory, especially for people with greater AD risk. These findings underscore the potential importance of proactive screening and treatment of REM OSA even if overall AHI appears low.

Association Between Sleep Quantity and Quality in Early Adulthood With Cognitive Function in Midlife

BACKGROUND AND OBJECTIVE

Growing evidence supports an association between sleep quality and risk of dementia. However, little is known about whether objectively measured sleep duration and quality influence cognition in midlife, a period of importance for understanding the direction of the association between sleep and dementia. We examined the association between sleep duration and quality, measured when participants were in their mid-30s to late 40s, and midlife cognition assessed 11 years later among Black and White adults.

METHODS

As part of the Coronary Artery Risk Development in Young Adults cohort study, sleep duration and quality were assessed objectively using wrist actigraphy and subjectively by Pittsburgh Sleep Quality Index (PSQI) at 2003-2005. During 2015-2016, we evaluated midlife cognition using the Digit Symbol Substitution Test (DSST), Stroop test, Rey Auditory Verbal Learning Test, Montreal Cognitive Assessment (MoCA), and Letter Fluency and Category Fluency tests. We used multivariable logistic regression to examine the association between sleep parameters and poor cognitive performance, which was defined as a score that was >1 SD below the mean score.

RESULTS

The 526 participants (58% women and 44% Black) had a mean age of 40.1 ± 3.6 years at baseline, a mean sleep duration of 6.1 ± 1.1 hours, and mean sleep fragmentation index (calculated as the sum of the percentage of time spent moving and the percentage of immobile periods ≤1 minute) of 19.2 ± 8.1%, and 239 (45.6%) participants reported poor sleep as defined by a PSQI global score of >5. After adjustment for demographics, education, smoking, body mass index, depression, physical activity, hypertension, and diabetes, those in the highest vs lowest tertile of sleep fragmentation index had over twice the odds of having poor cognitive performance (>1 SD below the mean) on the DSST (odds ratio [OR] = 2.97; 95% CI 1.34-6.56), fluency (OR = 2.42; 95% CI 1.17-5.02), and MoCA test (OR = 2.29; 95% CI 1.06-4.94). The association between sleep fragmentation and cognitive performance did not differ by race or sex. Objective sleep duration or subjective sleep quality was not associated with cognition in midlife.

DISCUSSION

Actigraphy-measured high sleep fragmentation rather than sleep duration was associated with worse cognition among middle-aged Black and White men and women. Sleep quality is important for cognitive health even as early as midlife.

The association between cortical gyrification and sleep in adolescents and young adults

STUDY OBJECTIVES

Healthy sleep is important for adolescent neurodevelopment, and relationships between brain structure and sleep can vary in strength over this maturational window. Although cortical gyrification is increasingly considered a useful index for understanding cognitive and emotional outcomes in adolescence, and sleep is also a strong predictor of such outcomes, we know relatively little about associations between cortical gyrification and sleep. We aimed to identify developmentally invariant (stable across age) or developmentally specific (observed only during discrete age intervals) gyrification-sleep relationships in young people.

METHODS

A total of 252 Neuroimaging and Pediatric Sleep Databank participants (9-26 years; 58.3% female) completed wrist actigraphy and a structural MRI scan. Local gyrification index (lGI) was estimated for 34 bilateral brain regions. Naturalistic sleep characteristics (duration, timing, continuity, and regularity) were estimated from wrist actigraphy. Regularized regression for feature selection was used to examine gyrification-sleep relationships.

RESULTS

For most brain regions, greater lGI was associated with longer sleep duration, earlier sleep timing, lower variability in sleep regularity, and shorter time awake after sleep onset. lGI in frontoparietal network regions showed associations with sleep patterns that were stable across age. However, in default mode network regions, lGI was only associated with sleep patterns from late childhood through early-to-mid adolescence, a period of vulnerability for mental health disorders.

CONCLUSIONS

We detected both developmentally invariant and developmentally specific ties between local gyrification and naturalistic sleep patterns. Default mode network regions may be particularly susceptible to interventions promoting more optimal sleep during childhood and adolescence.

Self-Reported Sleep Duration and Bedtime Are Associated with Dementia Risk in Community-Dwelling People Aged 40-74 Years: The Murakami Cohort Study

Background

Sleep is a potentially modifiable factor associated with dementia, including Alzheimer's disease, but current evidence supporting this is insufficient.

Objective

This study aimed to determine whether sleep duration and bedtime patterns are associated with the risk of dementia among middle-aged and older people.

Methods

This cohort study had an eight-year follow-up period. Participants were 13,601 community-dwelling people aged 40-74 years living in Murakami (Niigata, Japan). Data were collected using a self-administered questionnaire. Predictors were self-reported sleep duration and bedtime, and the outcome was newly-diagnosed dementia determined using the long-term care insurance database. Covariates were demographic characteristics, body mass index, smoking, alcohol consumption, total physical activity, insomnia symptoms, disease history, and either bedtime or sleep duration. Cox proportional hazard models were used to calculate hazard ratios (HRs).

Results

The mean age of participants at baseline was 59.2 years. Over a mean follow-up period of 8.0 years, 319 cases of dementia were observed. A long self-reported sleep duration relative to the reference sleep duration (7 hours) was associated with increased dementia risk, with the "8 hours" group (adjusted HR = 1.30, 95% CI:0.99-1.73) and "≥9 hours" group (adjusted HR = 1.46, 95% CI:1.00-2.15) having an increased risk (marginally significant) relative to the reference group. Early bedtime was associated with increased dementia risk (adjusted p for trend = 0.0010), with the "21 : 00 or earlier" group (adjusted HR = 1.61, 95% CI:1.14-2.28) having an increased risk relative to the reference ("23 : 00").

Conclusions

A long self-reported sleep duration and early bedtime are both associated with increased dementia risk in middle-aged and older people.

Decrements in Both Physical and Cognitive Function Are Associated With a Higher Symptom Burden in Oncology Patients

OBJECTIVES

Physical and cognitive function are two of the most important patient-reported outcomes. In oncology patients receiving chemotherapy (N = 1331), purposes were to identify subgroups of patients with distinct joint physical and cognitive function profiles and evaluate for differences in demographic and clinical characteristics, severity of common symptoms, and quality of life outcomes.

DATA SOURCES

Measures of physical and cognitive functions were obtained six times over two cycles of chemotherapy. All of the other measures were done prior to the second or third cycle of chemotherapy. Latent profile analysis was done to identify the distinct joint physical and cognitive function profiles. Differences among the profiles were evaluated using parametric and nonparametric tests.

CONCLUSION

Five distinct profiles were identified (ie, Very Low Physical and Low Cognitive Function [18.4%; Both Low], Low Physical and High Cognitive Function [19.8%], Moderate Physical and Low Cognitive Function [26.7%], Changing Physical and Cognitive Function [5.4%], and Normal Physical and Cognitive Function [29.7%]). Patients in the Both Low class had the highest symptom burden and the poorest quality of life. Over 70% of the sample had moderate to severe decrements in one or both of these extremely important patient outcomes.

IMPLICATIONS FOR NURSING PRACTICE

Clinicians need to assess for both physical and cognitive function using simple subjective and objective measures.

The association between cortical gyrification and sleep in adolescents and young adults

Study objectives

Healthy sleep is important for adolescent neurodevelopment, and relationships between brain structure and sleep can vary in strength over this maturational window. Although cortical gyrification is increasingly considered a useful index for understanding cognitive and emotional outcomes in adolescence, and sleep is also a strong predictor of such outcomes, we know relatively little about associations between cortical gyrification and sleep.

Methods

Using Local gyrification index (lGI) of 34 bilateral brain regions and regularized regression for feature selection, we examined gyrification-sleep relationships in the Neuroimaging and Pediatric Sleep databank (252 participants; 9-26 years; 58.3% female) and identified developmentally invariant (stable across age) or developmentally specific (observed only during discrete age intervals) brain-sleep associations. Naturalistic sleep characteristics (duration, timing, continuity, and regularity) were estimated from wrist actigraphy.

Results

For most brain regions, greater lGI was associated with longer sleep duration, earlier sleep timing, lower variability in sleep regularity, and shorter time awake after sleep onset. lGI in frontoparietal network regions showed associations with sleep patterns that were stable across age. However, in default mode network regions, lGI was only associated with sleep patterns from late childhood through early-to-mid adolescence, a period of vulnerability for mental health disorders.

Conclusions

We detected both developmentally invariant and developmentally specific ties between local gyrification and naturalistic sleep patterns. Default mode network regions may be particularly susceptible to interventions promoting more optimal sleep during childhood and adolescence.