Advances in pathophysiology and neuroimaging: Implications for sleep and dementia

Sleep Duration and Executive Function in Adults

PURPOSE OF REVIEW

To review the literature examining the relationship between sleep and cognition, specifically examining the sub-domain of executive function. We explore the impact of sleep deprivation and the important question of how much sleep is required for optimal cognitive performance. We consider how other sleep metrics, such as sleep quality, may be a more meaningful measure of sleep. We then discuss the putative mechanisms between sleep and cognition followed by their contribution to developing dementia.

RECENT FINDINGS

Sleep duration and executive function display a quadratic relationship. This suggests an optimal amount of sleep is required for daily cognitive processes. Poor sleep efficiency and sleep fragmentation are linked with poorer executive function and increased risk of dementia during follow-up. Sleep quality may therefore be more important than absolute duration. Biological mechanisms which may underpin the relationship between sleep and cognition include brain structural and functional changes as well as disruption of the glymphatic system. Sleep is an important modifiable lifestyle factor to improve daily cognition and, possibly, reduce the risk of developing dementia. The impact of optimal sleep duration and sleep quality may have important implications for every ageing individual.

Influence of Snoring on the Incidence of Metabolic Syndrome: A Community-Based Prospective Cohort Study in Rural Northeast China

In recent years, there has been an increase in the incidence of metabolic syndrome (MetS) in rural China. Thus, for better intervention, it is necessary to identify the possible risk factors of MetS. This community-based prospective cohort study was performed to evaluate the relationship between the snoring status and incidence of MetS. In this Northeast China rural cardiovascular health study, 4980 residents aged ≥35 years (2586 men and 2394 women; follow-up proportion: 87.5%) at baseline were recruited between 2012 and 2013 and were followed up between 2015 and 2017. The primary outcome was the incidence of MetS, as defined by the unified criteria for MetS defined in 2009. The residents were classified based on their snoring status, and the outcomes were compared between the two groups. The odds ratio (OR) for MetS incidence was estimated using a logistic regression model and adjusted for confounding factors. With a median follow-up duration of 4.6 years, the MetS incidence was higher among the snorers (men, 26.2%; women, 33.5%) than in the non-snorers (men, 19.7%; women, 23.2%). The participants' diastolic blood pressure was increased at follow-up as compared with the baseline values among the male snorers; however, a decrease was noted among the male non-snorers. Similarly, the female snorers had higher blood glucose levels during the follow-up, whereas the non-snorers had lower blood sugar levels. A significant association was noted between snoring and the incidence of MetS (adjusted OR = 1.51; 95% confidence interval = 1.32-1.74). Moreover, the incidence of severe snoring increased with increased levels of snoring, with severe snorers having an OR twice as high as that of the non-snorers (adjusted OR = 2.10; 95% confidence interval = 1.38-3.20). Overall, snoring was independently associated with a higher incidence of newly diagnosed MetS in rural Northeast China. Thus, more attention should be paid to residents with snoring problems.

Potentially Inappropriate Medication Among People With Dementia in China: A Nationwide Cross-Sectional Study

Objectives: The purpose of this study was to explore the prevalence of potentially inappropriate medication (PIM) among older outpatients (age ≥ 65 years old) with dementia in eight cities in China using the AGS Beers criteria of 2019 and to identify the potential factor increasing the number of PIMs.

Methods: A cross-sectional study about PIM in older outpatients with dementia from January 2020 to December 2020 was carried out in eight cities in China, Chengdu, Beijing, Guangzhou, Shanghai, Shenyang, Tianjin, Zhengzhou, and Hangzhou, distributing five major geographical regions in China (east, west, north, south, central). The diagnosis of dementia was based on the International Classification of Diseases (ICD-10) to identify. Based on the 2019 AGS Beers criteria, the PIM prescriptions were evaluated. The identification of potential factors was completed using a binary logistic regression model.

Results: Of 18,624 older outpatients with dementia, 3.52% were detected with 1 PIM, and 35.91% received at least two PIMs. The antipsychotic drugs quetiapine and olanzapine were most frequently prescribed in patients with PIM, accounting for 8.01 and 7.36%, respectively. Logistic regression analyses showed that female patients with dementia aged >80 years who took more medications were exposed easily to PIM use.

Conclusion: PIM use among older outpatients with dementia in China is highly prevalent, and the associated risk factors were increasing age, female sex, and number of medications. The most frequently prescribed drugs by clinicians were anpsychotropic drugs, which were much more frequent than other drugs.

Sleep-disordered breathing was associated with lower health-related quality of life and cognitive function in a cross-sectional study of older adults

Background and objective

The clinical significance of sleep‐disordered breathing (SDB) in older age is uncertain. This study determined the prevalence and associations of SDB with mood, daytime sleepiness, quality of life (QOL) and cognition in a relatively healthy older Australian cohort.

Methods

A cross‐sectional analysis was conducted from the Study of Neurocognitive Outcomes, Radiological and retinal Effects of Aspirin in Sleep Apnoea. Participants completed an unattended limited channel sleep study to measure the oxygen desaturation index (ODI) to define mild (ODI 5–15) and moderate/severe (ODI ≥ 15) SDB, the Centre for Epidemiological Studies Scale, the Epworth Sleepiness Scale, the 12‐item Short‐Form for QOL and neuropsychological tests.

Results

Of the 1399 participants (mean age 74.0 years), 36% (273 of 753) of men and 25% (164 of 646) of women had moderate/severe SDB. SDB was associated with lower physical health‐related QOL (mild SDB: beta coefficient [β] −2.5, 95% CI −3.6 to −1.3, p < 0.001; moderate/severe SDB: β −1.8, 95% CI −3.0 to −0.6, p = 0.005) and with lower global composite cognition (mild SDB: β −0.1, 95% CI −0.2 to 0.0, p = 0.022; moderate/severe SDB: β −0.1, 95% CI −0.2 to 0.0, p = 0.032) compared to no SDB. SDB was not associated with daytime sleepiness nor depression.

Conclusion

SDB was associated with lower physical health‐related quality of life and cognitive function. Given the high prevalence of SDB in older age, assessing QOL and cognition may better delineate subgroups requiring further management, and provide useful treatment target measures for this age group.

The clinical implications for sleep‐disordered breathing (SDB) in older age remain uncertain. This study of healthy community‐dwelling older Australians reports significant associations between SDB and a lower physical health‐related quality of life, in contrast to other studies of SDB in older age, and between SDB and lower cognitive function.

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Dementia in military and veteran populations: a review of risk factors-traumatic brain injury, post-traumatic stress disorder, deployment, and sleep

The military population face a unique set of risk factors that may increase the risk of being diagnosed with dementia. Traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD) have a higher prevalence in this group in comparison to the civilian population. By delving into the individual relationships between TBI and dementia, and PTSD and dementia, we are able to better explore dementia in the military and veteran populations. While there are some inconsistencies in results, the TBI-dementia association has become more widely accepted. Moderate-to-severe TBI has been found to increase the risk of being diagnosed with Alzheimer's disease. A correlation between PTSD and dementia has been established, however, whether or not it is a causal relationship remains unclear. Factors such as blast, combat and chemical exposure may occur during a deployment, along with TBI and/or PTSD diagnosis, and can impact the risk of dementia. However, there is a lack of literature exploring the direct effects of deployment on dementia risk. Sleep problems have been observed to occur in those following TBI, PTSD and deployment. Poor sleep has been associated with possible dementia risk. Although limited studies have focused on the link between sleep and dementia in military and veteran populations, sleep is a valuable factor to study due to its association and interconnection with other military/veteran factors. This review aims to inform of various risk factors to the cognitive health of military members and veterans: TBI, PTSD, deployment, and sleep.

Cognition and 20-year subsequent sleep disturbances

INTRODUCTION

There is a paucity of data exploring the extent that preclinical cognitive changes are predictive of subsequent sleep outcomes.

METHODS

Logistic regression models were used to evaluate data from a cohort of 196 African American adults who had measures of cognitive function assessed at 2 time points during a 20-year period across the mid- to late-life transition. Cognitive testing included the Delayed Word Recall, the Digit Symbol Substitution, and the Word Fluency tests, which were summarized as a composite cognitive z-score. Sleep apnea was measured by in-home sleep apnea testing and sleep duration and quality were derived from 7-day wrist actigraphy at the end of the study period.

RESULTS

A one standard deviation (SD) lower composite cognitive z-score at baseline was significantly associated with greater odds of low sleep efficiency (<85%) (odds ratio [OR] = 1.85, 95% confidence interval [CI] = 1.13, 3.04) and greater odds of increased wakefulness after sleep onset time (WASO; >60 minutes) (OR = 1.65, 95% CI = 1.05, 2.60) in adjusted models. A one SD faster rate of cognitive decline over the study period was significantly associated with greater odds of low sleep efficiency (OR = 1.68, 95% CI = 1.04, 2.73), greater odds of sleep fragmentation (>35%); (OR = 1.73, 95% CI = 1.05, 2.85), and greater odds of increased WASO (OR = 1.85, 95% CI = 1.15, 2.95) in adjusted models. Neither baseline cognitive z-score nor rate of cognitive decline was associated with sleep apnea or the total average sleep duration.

CONCLUSION

Cognition at baseline and change over time predicts sleep quality and may reflect common neural mechanisms and vulnerabilities.

Supporting older people with dementia to sleep well while in hospital

Optimal sleep is essential for health, well-being and recovery from illness but can be challenging to achieve in the acute hospital setting. Older people with dementia may find it particularly challenging to sleep well in the unfamiliar and disruptive environment of a hospital ward. Suboptimal sleep may potentially accelerate the progression of dementia. Conversely, optimal sleep may slow disease progression. Nursing staff who care for older people with dementia in hospital therefore need to find ways of supporting them to sleep well. This article explores the causes and consequences of suboptimal sleep in hospitalised older people with dementia and discusses evidence-based interventions that nursing staff can use to support these patients to sleep well, including person-centred sleep care, changes to sleep hygiene, environmental adaptations and changes to medicine regimens.

The future of sleep-disordered breathing: A public health crisis

Find the whole series here https://onlinelibrary.wiley.com/doi/toc/10.1111/(ISSN)1440-1843.new-frontiers-in-sleep-disordered-breathing See cover image.