Neurocognitive dysfunction associated with sleep quality and sleep apnea in patients with mild cognitive impairment

Long Objective Sleep Duration is a Marker of Cognitive Impairment in Older Adults: Findings from the Cretan Aging Cohort

 We examined associations between objective sleep duration and cognitive status in older adults initially categorized as cognitively non-impaired (CNI, n = 57) or diagnosed with mild cognitive impairment (MCI, n = 53). On follow-up, 8 years later, all participants underwent neuropsychiatric/neuropsychological evaluation and 7-day 24-h actigraphy. On re-assessment 62.7% of participants were cognitively declined. Patients who developed dementia had significantly longer night total sleep time (TST) than persons with MCI who, in turn, had longer night TST than CNI participants. Objective long sleep duration is a marker of worse cognitive status in elderly with MCI/dementia and this association is very strong in older adults.

Sleep structure assessed by objective measurement in patients with mild cognitive impairment: A meta-analysis

OBJECTIVES

A meta-analysis was used to explore the characteristic changes in objective sleep structure of patients with mild cognitive impairment (MCI) compared with cognitively healthy older adults.

MATERIALS AND METHODS

PubMed, EMBAS, Cochrane Library, Scopus, and Web of Science were searched until November 2023. A literature quality evaluation was performed according to the Newcastle-Ottawa Scale, and a meta-analysis was performed by RevMan 5.3 software.

RESULTS

Fifteen studies with 771 participants were finally included. Compared with normal control groups, patients with MCI had a decreased total sleep time by 34.44 min, reduction in sleep efficiency by 7.96 %, increased waking after sleep onset by 19.61 min, and increased sleep latency by 6.97 min. Ten included studies showed that the patients with MCI had increased N1 sleep by 2.72 % and decreased N3 sleep by 0.78 %; however, there was no significant difference between the MCI and control groups in percentage of N2 sleep. Moreover, Twelve included studies reported the MCI groups had shorter REM sleep of 2.69 %.

CONCLUSION

Our results provide evidence of abnormal sleep architecture in patients with MCI. As a "plastic state," abnormal sleep architecture may be a promising therapeutic target for slowing cognitive decline and dementia prevention.

Obstructive Sleep Apnea Among Patients with Mild Cognitive Impairment

Background

Obstructive sleep apnea (OSA) is associated with cognitive disorders, but little is known about prevalence of co-occurring OSA and mild cognitive impairment (MCI) as well as about co-occurring OSA and Alzheimer's disease (AD). Pathophysiological models integrating OSA, cognitive deficits and neurodegeneration remain speculative. Findings in this area could contribute to the knowledge about pathophysiological processes in cognitive disorders and neurodegenerative processes, be helpful for the diagnosis of cognitive disorders and provide approaches for the treatment of cognitive disorders.

Objective

Examining the prevalence of OSA and patterns of cognitive deficits as well as AD biomarker profiles associated with OSA in a cohort of 104 MCI patients.

Methods

Assessments used include: respiratory polygraphy, The Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Battery (CERAD NB), Tau, phosphoTau181, amyloid-β-1-42/1-40, 18F-fluorodeoxyglucose positron emission tomography (F18-FDG-PET).

Results

Prevalence of OSA of any severity: 58,7% (Apnea Hypopnea Index (AHI)≥5/h), OSA in a moderate-to-severe extent (AHI≥15/h): 25%. Only 13.1% of MCI patients with OSA reported daytime sleepiness. MCI-OSA patients showed no specific neuropsychological pattern. Presence of OSA was not associated with specific AD biomarker profiles in the whole study group besides a positive association between AD positivity in an AD biomarker sub cohort.

Conclusions

OSA is highly prevalent in patients with MCI. It might often remain undiagnosed as only a small number of MCI-OSA patients report daytime sleepiness. OSA could contribute to MCI symptoms and even to AD pathology. Further research is needed to validate these findings and to investigate possible pathophysiological relationships between OSA and MCI as well as between OSA and AD.

Association between circadian sleep regulation and cortical gyrification in young and older adults

The circadian system orchestrates sleep timing and structure and is altered with increasing age. Sleep propensity, and particularly REM sleep is under strong circadian control and has been suggested to play an important role in brain plasticity. In this exploratory study, we assessed whether surface-based brain morphometry indices are associated with circadian sleep regulation and whether this link changes with age. Twenty-nine healthy older (55-82 years; 16 men) and 28 young participants (20-32 years; 13 men) underwent both structural magnetic resonance imaging and a 40-h multiple nap protocol to extract sleep parameters over day and night time. Cortical thickness and gyrification indices were estimated from T1-weighted images acquired during a classical waking day. We observed that REM sleep was significantly modulated over the 24-h cycle in both age groups, with older adults exhibiting an overall reduction in REM sleep modulation compared to young individuals. Interestingly, when taking into account the observed overall age-related reduction in REM sleep throughout the circadian cycle, higher day-night differences in REM sleep were associated with increased cortical gyrification in the right inferior frontal and paracentral regions in older adults. Our results suggest that a more distinctive allocation of REM sleep over the 24-h cycle is associated with regional cortical gyrification in aging, and thereby point towards a protective role of circadian REM sleep regulation for age-related changes in brain organization.

Gut microbiota: Candidates for a novel strategy for ameliorating sleep disorders

The aim of this review was to evaluate the feasibility of treating sleep disorders using novel gut microbiota intervention strategies. Multiple factors can cause sleep disorders, including an imbalance in the gut microbiota. Studies of the microbiome-gut-brain axis have revealed bidirectional communication between the central nervous system and gut microbes, providing a more comprehensive understanding of mood and behavioral regulatory patterns. Changes in the gut microbiota and its metabolites can stimulate the endocrine, nervous, and immune systems, which regulate the release of neurotransmitters and alter the activity of the central nervous system, ultimately leading to sleep disorders. Here, we review the main factors affecting sleep, discuss possible pathways and molecular mechanisms of the interaction between sleep and the gut microbiota, and compare common gut microbiota intervention strategies aimed at improving sleep physiology.

Characteristics of macroscopic sleep structure in patients with mild cognitive impairment: a systematic review

Objectives

Conducting a systematic analysis of objective measurement tools to assess the characteristics of macroscopic sleep architecture in patients with mild cognitive impairment (MCI), amnestic MCI (aMCI), and non-amnestic MCI (naMCI) in order to provide sleep disorder guidance for MCI patients.

Methods

PubMed, EMbase, Web of Science, Cochrane Library, CNKI, SinoMed, Wanfang Data, and VIP Data were examined to find literature relating to sleep in patients with MCI, aMCI, and naMCI, with a search time frame of build to April 2023. Following independent literature screening, data extraction, and quality evaluation by two researchers, statistical analysis was performed using RevMan 5.4 software.

Results

Twenty-five papers with 1,165 study subjects were included. Patients with MCI and aMCI were found to have altered total sleep time (TST), reduced sleep efficiency (SE), more wake-time after sleep onset (WASO), longer sleep latency (SL), a higher proportion of N1 stage and a lower proportion of N2 and N3 stage. naMCI was only found to have statistically significant differences in WASO.

Conclusions

The results of this study provide evidence for macroscopic sleep architecture abnormalities among MCI patients with sleep disorders. Maintaining a normal sleep time, improving SE, and reducing sleep fragmentation may have an association with a slowed development of cognitive impairment. Further exploration is required of the effects each component of macroscopic sleep structure after the intervention has on altered sleep disturbance and cognition in MCI, aMCI, and naMCI.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023401937, identifier: CRD42023401937.

The prevalence of obstructive sleep apnoea risk factors in individuals with cognitive impairment: south London cross-sectional study

AIMS AND METHOD

We aimed to determine the prevalence of risk factors for obstructive sleep apnoea (OSA) in patients with mild cognitive impairment (MCI) or dementia. Using patient records across a 5 year period, we identified 16 855 patients with dementia or MCI. We gave scores for keywords relating to each modified STOP BANG parameter in patient progress notes. Based on individual scores, we stratified the population into groups with low, intermediate and high risk of OSA.

RESULTS

Our population had a high prevalence of risk factors and consequently high risk scores for OSA (18.21% high risk). Parameters directly related to sleep had a low prevalence.

CLINICAL IMPLICATIONS

The risk of developing or having OSA is high among patients with MCI and dementia. Low sleep parameter frequency probably suggests poor documentation of sleep rather than true prevalence. Our findings support the implementation of the STOP BANG or a similar screening tool as a standardised method to identify OSA risk in memory clinics.

Sleep and Cognition: A Narrative Review Focused on Older Adults

Little is known regarding sleep's association with the traditional developmental course of late-life cognitive functioning. As the number of older adults increases worldwide, an enhanced understanding of age-related changes in sleep and cognition is necessary to slow decline and promote optimal aging. This review synthesizes the extant literature on sleep and cognitive function in healthy older adults, older adults with insomnia, and older adults with sleep apnea, incorporating information on the potential promising effects of treating poor sleep on cognitive outcomes in older adults. Unifying theories of the sleep-cognition association, possible mechanisms of action, and important unanswered questions are identified.

Subjective cognitive decline and self-reported sleep problems: The SCIENCe project

We aim to investigate the frequency and type of sleep problems in memory clinic patients with subjective cognitive decline (SCD) and their association with cognition, mental health, brain magnetic resonance imaging (MRI), and cerebrospinal fluid (CSF) biomarkers. Three hundred eight subjects (65 ± 8 years, 44% female) were selected from the Subjective Cognitive Impairment Cohort (SCIENCe) project. All subjects answered two sleep questionnaires, Berlin Questionnaire (sleep apnea) and Pittsburgh Sleep Quality Index (sleep quality) and underwent a standardized memory clinic work-up. One hundred ninety-eight (64%) subjects reported sleep problems, based on 107 (35%) positive screenings on sleep apnea and 162 (53%) on poor sleep quality. Subjects with sleep problems reported more severe depressive symptoms, more anxiety, and more severe SCD. Cognitive tests, MRI, and CSF biomarkers did not differ between groups. Our results suggest that improvement of sleep quality and behaviors are potential leads for treatment in many subjects with SCD to relieve the experienced cognitive complaints.

Apnea Detection in Polysomnographic Recordings Using Machine Learning Techniques

Sleep disorders are diagnosed in sleep laboratories by polysomnography, a multi-parameter examination that monitors biological signals during sleep. The subsequent evaluation of the obtained records is very time-consuming. The goal of this study was to create an automatic system for evaluation of the airflow and SpO2 channels of polysomnography records, through the use of machine learning techniques and a large database, for apnea and desaturation detection (which is unusual in other studies). To that end, a convolutional neural network (CNN) was designed using hyperparameter optimization. It was then trained and tested for apnea and desaturation. The proposed CNN was compared with the commonly used k-nearest neighbors (k-NN) method. The classifiers were designed based on nasal airflow and blood oxygen saturation signals. The final neural network accuracy for apnea detection reached 84%, and that for desaturation detection was 74%, while the k-NN classifier reached accuracies of 83% and 64% for apnea detection and desaturation detection, respectively.

The Importance of Diagnosing and the Clinical Potential of Treating Obstructive Sleep Apnea to Delay Mild Cognitive Impairment and Alzheimer's Disease: A Special Focus on Cognitive Performance

Obstructive sleep apnea (OSA) is a highly frequent sleep disorder in the middle-aged and older population, and it has been associated with an increased risk of developing cognitive decline and dementia, including mild cognitive impairment (MCI) and Alzheimer's disease (AD). In more recent years, a growing number of studies have focused on: 1) the presence of OSA in patients with MCI or AD, 2) the link between OSA and markers of AD pathology, and 3) the role of OSA in accelerating cognitive deterioration in patients with MCI or AD. Moreover, some studies have also assessed the effects of continuous positive airway pressure (CPAP) treatment on the cognitive trajectory in MCI and AD patients with comorbid OSA. This narrative review summarizes the findings of studies that analyzed OSA as a risk factor for developing MCI and/or AD in the middle-aged and older populations with a special focus on cognition. In addition, it describes the results regarding the effects of CPAP treatment in hampering the progressive cognitive decline in AD and delaying the conversion to AD in MCI patients. Considering the importance of identifying and treating OSA in patients with MCI or AD in order to prevent or reduce the progression of cognitive decline, further larger and adequately powered studies are needed both to support these findings and to set programs for the early recognition of OSA in patients with cognitive impairment.

A case for the role of memory consolidation in speech-motor learning

This review will explore the role of memory consolidation in speech-motor learning. Existing frameworks of speech-motor control account for the protracted time course of building the speech-motor representation. These perspectives converge on the speech-motor representation as a multimodal unit that is comprised of auditory, motor, and linguistic information. Less is known regarding the memory mechanisms that support the emergence of a generalized speech-motor unit from instances of speech production. Here, we consider the broader learning and memory consolidation literature and how it may apply to speech-motor learning. We discuss findings from relevant domains on the stabilization, enhancement, and generalization of learned information. Based on this literature, we provide our predictions for the division of labor between conscious and unconscious memory systems in speech-motor learning, and the subsequent effects of time and sleep to memory consolidation. We identify both the methodological challenges, as well as the practical importance, of advancing this work empirically. This discussion provides a foundation for building a memory-based framework for speech-motor learning.

Obstructive Sleep Apnea and Cognitive Decline: A Review of Potential Vulnerability and Protective Factors

Around 40% of dementia risk is attributable to modifiable risk factors such as physical inactivity, hypertension, diabetes and obesity. Recently, sleep disorders, including obstructive sleep apnea (OSA), have also been considered among these factors. However, despite several epidemiological studies investigating the link between OSA and cognitive decline, there is still no consensus on whether OSA increases the risk of dementia or not. Part of the heterogeneity observed in previous studies might be related to some individual characteristics that modulate the association between OSA and cognitive decline. In this narrative review, we present these individual characteristics, namely, age, sex, menopause, obesity, diabetes mellitus, hypertension, cardiovascular diseases, smoking, excessive alcohol consumption, depression, air pollution, Apolipoprotein E ε4 allele, physical activity, and cognitive reserve. To date, large cohort studies of OSA and cognitive decline tended to statistically control for the effects of these variables, but whether they interact with OSA to predict cognitive decline remains to be elucidated. Being able to better predict who is at risk of cognitive decline when they have OSA would improve clinical management and treatment decisions, particularly when patients present relatively mild OSA.

Slow Wave Sleep and EEG Delta Spectral Power are Associated with Cognitive Function in Parkinson's Disease

BACKGROUND

Cognitive and sleep dysfunction are common non-motor symptoms in Parkinson's disease (PD).

OBJECTIVE

Determine the relationship between slow wave sleep (SWS) and cognitive performance in PD.

METHODS

Thirty-two PD participants were evaluated with polysomnography and a comprehensive level II neurocognitive battery, as defined by the Movement Disorders Society Task Force for diagnosis of PD-mild cognitive impairment. Raw scores for each test were transformed into z-scores using normative data. Z-scores were averaged to obtain domain scores, and domain scores were averaged to determine the Composite Cognitive Score (CCS), the primary outcome. Participants were grouped by percent of SWS into High SWS and Low SWS groups and compared on CCS and other outcomes using 2-sided t-tests or Mann-Whitney U. Correlations of cognitive outcomes with sleep architecture and EEG spectral power were performed.

RESULTS

Participants in the High SWS group demonstrated better global cognitive function (CCS) (p = 0.01, effect size: r = 0.45). In exploratory analyses, the High SWS group showed better performance in domains of executive function (effect size: Cohen's d = 1.05), language (d = 0.95), and processing speed (d = 1.12). Percentage of SWS was correlated with global cognition and executive function, language, and processing speed. Frontal EEG delta power during N3 was correlated with the CCS and executive function. Cognition was not correlated with subjective sleep quality.

CONCLUSION

Increased SWS and higher delta spectral power are associated with better cognitive performance in PD. This demonstrates the significant relationship between sleep and cognitive function and suggests that interventions to improve sleep might improve cognition in individuals with PD.

Macro and micro sleep architecture and cognitive performance in older adults

We sought to determine which facets of sleep neurophysiology were most strongly linked to cognitive performance in 3,819 older adults from two independent cohorts, using whole-night electroencephalography. From over 150 objective sleep metrics, we identified 23 that predicted cognitive performance, and processing speed in particular, with effects that were broadly independent of gross changes in sleep quality and quantity. These metrics included rapid eye movement duration, features of the electroencephalography power spectra derived from multivariate analysis, and spindle and slow oscillation morphology and coupling. These metrics were further embedded within broader associative networks linking sleep with aging and cardiometabolic disease: individuals who, compared with similarly aged peers, had better cognitive performance tended to have profiles of sleep metrics more often seen in younger, healthier individuals. Taken together, our results point to multiple facets of sleep neurophysiology that track coherently with underlying, age-dependent determinants of cognitive and physical health trajectories in older adults.

Multicenter Study on Sleep and Circadian Alterations as Objective Markers of Mild Cognitive Impairment and Alzheimer’s Disease Reveals Sex Differences

Background: Circadian and sleep disturbances are associated with increased risk of mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Wearable activity trackers could provide a new approach in diagnosis and prevention. Objective: To evaluate sleep and circadian rhythm parameters, through wearable activity trackers, in MCI and AD patients as compared to controls, focusing on sex dissimilarities. Methods: Based on minute level data from consumer wearable devices, we analyzed actigraphic sleep parameters by applying an electromedical type I registered algorithm, and the corresponding circadian variables in 158 subjects: 86 females and 72 males (42 AD, 28 MCI, and 88 controls). Moreover, we used a confusion-matrix chart method to assess accuracy, precision, sensitivity, and specificity of two decision-tree models based on actigraphic data in predicting disease or health status. Results: Wake after sleep onset (WASO) was higher (p < 0.001) and sleep efficiency (SE) lower (p = 0.003) in MCI, and Sleep Regularity Index (SRI) was lower in AD patients compared to controls (p = 0.004). SE was lower in male AD compared to female AD (p = 0.038) and SRI lower in male AD compared to male controls (p = 0.008), male MCI (p = 0.047), but also female AD subjects (p = 0.046). Mesor was significantly lower in males in the overall population. Age reduced the dissimilarities for WASO and SE but demonstrated sex differences for amplitude (p = 0.009) in the overall population, controls (p = 0.005), and AD subjects (p = 0.034). The confusion-matrices showed good predictive power of actigraphic data. Conclusion: Actigraphic data could help identify disease or health status. Sex (possibly gender) differences could impact on neurodegeneration and disease trajectory with potential clinical applications.

Comparison of commonly used screening tools for determining obstructive sleep apnea amongst aviation employees

INTRODUCTION

Epidemiological evidence suggests the prevalence of Obstructive Sleep Apnea (OSA) ranges 9-38%. Multiple screening tools are used to aid diagnosis. In professions that require high levels of attentiveness, safety, and responsibility for other's lives, inaccuracies and biases are probable for self-reported data. We sought to assess the best screening tool for OSA amongst aircraft pilots and air traffic controllers (ATCs).

METHODS

Data were collected as part of routine clinical care for patients presenting to Sleep Disorders Specialized Clinic. A total 1384 patients attended the clinic (2012-2018), of which 254 were either pilots or ATCs. Patients responded to three questionnaires, regularly used for OSA screening: 1) Epworth Sleepiness Scale (ESS); 2) Berlin Questionnaire (BQ); 3) STOP-BANG Questionnaire (SBQ). We used non-parametric ROC analysis, sensitivity, and specificity measures, along with positive and negative predictive values (PPV/NPV) to determine the most accurate diagnostic instrument.

RESULTS

The ROC (95% CI) for the ESS, BQ, and SBQ was 0.49 (0.39-0.59), 0.58 (0.49-0.67), and 0.56 (0.47-0.65), respectively. When the SBQ was used in combination with the ESS, the sensitivity was high at 100% (78.2-100.0), as were the PPV and NPV, 83.3% (58.6-96.4) and 100.0 (2.5-100.0), respectively.

CONCLUSION

The SBQ, in combination with the ESS, was the most reliable diagnostic tool for OSA in pilots and ATCs. Physicians should prioritize use of these screening tools for predicting OSA when assessing those working in the aviation industry and similar occupational groups, such as drivers. Given the scarcity of literature in this population, we recommend future studies replicate ours to either confirm or refute the findings.

Modulation of Slow-Wave Sleep: Implications for Psychiatry

PURPOSE OF REVIEW

The objectives of this review are to examine and integrate existing empirical evidence regarding the impact of slow-wave sleep (SWS) modulation on memory and executive function performance in individuals with psychiatric disorders, and to examine the feasibility of integrating SWS modulation into psychiatric care.

RECENT FINDINGS

SWS modulation in individuals with psychiatric disorders resulted in changes to SWS across multiple psychiatric disorders, using all stimulation methods. SWS stimulation was associated with improved cognitive performance. SWS modulation using acoustic stimulation resulted in improved cognitive performance in children with ADHD, and the use of transcranial stimulation was associated with improved cognitive performance in individuals with mild cognitive impairment. Significant relationships between changes in SWS and cognitive improvement were found for individual with mild cognitive impairment following the use of acoustic or transcranial stimulation night. Our review reveals partial support to the potential efficacy of SWS modulation as a transdiagnostic intervention that uses sleep to improve cognitive functions of individuals diagnosed with psychiatric disorders and cognitive deficits. It further highlights multiple barriers pertaining to the feasibility of integrating SWS modulation into clinical practice and proposes ways to improve it.

Objective measurement of sleep in mild cognitive impairment: A systematic review and meta-analysis

Older adults with mild cognitive impairment (MCI) are at-risk of developing dementia, particularly Alzheimer's disease. While some research suggests that alterations in sleep architecture may mediate cognitive decline, the nature and magnitude of changes to sleep macro- (sleep stages) and micro-architecture (electroencephalography (EEG) oscillations) in MCI is not yet clear. This study aimed to systematically review and meta-analyse case-control studies objectively measuring sleep in MCI. A systematic search was conducted using PubMed, Scopus, Web of Science, Embase and Psycinfo databases and after review, a total of 10 studies met inclusion criteria. Of these, all reported sleep macro-architecture and four reported micro-architecture outcomes. A combined total of 430 participants (209 with and 221 without MCI) underwent objective sleep assessments in the included full text articles. Findings show that compared to healthy controls, those with MCI have pronounced changes in sleep macro-architecture with greater wake after sleep onset, reduced total sleep time, lower sleep efficiency, longer sleep onset latency, longer rapid eye movement sleep (REM) latency, reduced REM sleep, greater N1 sleep, and worse severity of hypoxemia. Pooling of sleep micro-architecture EEG measures was not possible due to limited studies, however reduced spindles in non-REM sleep and greater EEG slowing in REM sleep were reported.

Randomized, Controlled Trial of Exercise on Objective and Subjective Sleep in Parkinson's Disease

BACKGROUND

Sleep dysfunction is common and disabling in persons with Parkinson's Disease (PD). Exercise improves motor symptoms and subjective sleep quality in PD, but there are no published studies evaluating the impact of exercise on objective sleep outcomes. The goal of this study was to to determine if high-intensity exercise rehabilitation combining resistance training and body-weight interval training, compared with a sleep hygiene control improved objective sleep outcomes in PD.

METHODS

Persons with PD (Hoehn & Yahr stages 2-3; aged ≥45 years, not in a regular exercise program) were randomized to exercise (supervised 3 times a week for 16 weeks; n = 27) or a sleep hygiene, no-exercise control (in-person discussion and monthly phone calls; n = 28). Participants underwent polysomnography at baseline and post-intervention. Change in sleep efficiency was the primary outcome, measured from baseline to post-intervention. Intervention effects were evaluated with general linear models with measurement of group × time interaction. As secondary outcomes, we evaluated changes in other aspects of sleep architecture and compared the effects of acute and chronic training on objective sleep outcomes.

RESULTS

The exercise group showed significant improvement in sleep efficiency compared with the sleep hygiene group (group × time interaction: F = 16.0, P < 0.001, d = 1.08). Other parameters of sleep architecture also improved in exercise compared with sleep hygiene, including total sleep time, wake after sleep onset, and slow-wave sleep. Chronic but not acute exercise improved sleep efficiency compared with baseline.

CONCLUSIONS

High-intensity exercise rehabilitation improves objective sleep outcomes in PD. Exercise is an effective nonpharmacological intervention to improve this disabling nonmotor symptom in PD. © 2020 International Parkinson and Movement Disorder Society.

Obstructive sleep apnea, cognition and Alzheimer's disease: A systematic review integrating three decades of multidisciplinary research

Increasing evidence links cognitive-decline and Alzheimer's disease (AD) to various sleep disorders, including obstructive sleep apnea (OSA). With increasing age, there are substantial differences in OSA's prevalence, associated comorbidities and phenotypic presentation. An important question for sleep and AD researchers is whether OSA's heterogeneity results in varying cognitive-outcomes in older-adults compared to middle-aged adults. In this review, we systematically integrated research examining OSA and cognition, mild cognitive-impairment (MCI) and AD/AD biomarkers; including the effects of continuous positive airway pressure (CPAP) treatment, particularly focusing on characterizing the heterogeneity of OSA and its cognitive-outcomes. Broadly, in middle-aged adults, OSA is often associated with mild impairment in attention, memory and executive function. In older-adults, OSA is not associated with any particular pattern of cognitive-impairment at cross-section; however, OSA is associated with the development of MCI or AD with symptomatic patients who have a higher likelihood of associated disturbed sleep/cognitive-impairment driving these findings. CPAP treatment may be effective in improving cognition in OSA patients with AD. Recent trends demonstrate links between OSA and AD-biomarkers of neurodegeneration across all age-groups. These distinct patterns provide the foundation for envisioning better characterization of OSA and the need for more sensitive/novel sleep-dependent cognitive assessments to assess OSA-related cognitive-impairment.

Plasma Extracellular Vesicles in Children with OSA Disrupt Blood-Brain Barrier Integrity and Endothelial Cell Wound Healing in Vitro

Pediatric obstructive sleep apnea (P-OSA) is associated with neurocognitive deficits and endothelial dysfunction, suggesting the possibility that disruption of the blood-brain barrier (BBB) may underlie these morbidities. Extracellular vesicles (EVs), which include exosomes, are small particles involved in cell-cell communications via different mechanisms and could play a role in OSA-associated end-organ injury. To examine the roles of EVs in BBB dysfunction, we recruited three groups of children: (a) absence of OSA or cognitive deficits (CL, n = 6), (b) OSA but no evidence of cognitive deficits (OSA-NC(-), n = 12), and (c) OSA with evidence of neurocognitive deficits (OSA-NC(+), n = 12). All children were age-, gender-, ethnicity-, and BMI-z-score-matched, and those with OSA were also apnea-hypopnea index (AHI)-matched. Plasma EVs were characterized, quantified, and applied on multiple endothelial cell types (HCAEC, HIAEC, human HMVEC-D, HMVEC-C, HMVEC-L, and hCMEC/D3) while measuring monolayer barrier integrity and wound-healing responses. EVs from OSA children induced significant declines in hCMEC/D3 transendothelial impedance compared to CL (p < 0.001), and such changes were greater in NC(+) compared to NC(-) (p < 0.01). The effects of EVs from each group on wound healing for HCAEC, HIAEC, HMVED-d, and hCMEC/D3 cells were similar, but exhibited significant differences across the three groups, with evidence of disrupted wound healing in P-OSA. However, wound healing in HMVEC-C was only affected by NC(+) (p < 0.01 vs. NC(-) or controls (CO). Furthermore, no significant differences emerged in HMVEC-L cell wound healing across all three groups. We conclude that circulating plasma EVs in P-OSA disrupt the integrity of the BBB and exert adverse effects on endothelial wound healing, particularly among OSA-NC(+) children, while also exhibiting endothelial cell type selectivity. Thus, circulating EVs cargo may play important roles in the emergence of end-organ morbidity in pediatric OSA.

"Sleep Well, Think Well" Group Program for Mild Cognitive Impairment: A Randomized Controlled Pilot Study

Objective/Background: Sleep-wake disturbance is associated with poor cognitive functioning and several other adverse outcomes that increase dementia risk in older adults. Targeting sleep-wake disturbance in individuals at risk for dementia may be an important treatment. This study evaluated the efficacy of a four-session multicomponent group intervention for participants with mild cognitive impairment (MCI). Participants: Thirty-five older adults with MCI (mean age = 69.7 years, SD = 9.1), were recruited. MCI was determined via consensus from neuropsychological, medical, and neurological review. Methods: Participants were randomized to the "Sleep Well, Think Well" (SWTW) group condition or a passive control group. The SWTW group received four fortnightly face-to-face sessions conducted by an experienced sleep psychologist and neuropsychologist. The control group received written material detailing strategies to improve sleep quality. Both groups received fortnightly coaching phone calls. The primary outcome was subjective sleep quality, measured by the Pittsburgh Sleep Quality Index (PSQI). Secondary outcomes included actigraphy sleep measures, daytime sleepiness, cognitive functioning, and depression severity. Results: The SWTW intervention was associated with a large and statistically significant improvement in subjective sleep quality (Cohen's d = 0.83, p < 0.02). A moderate nonsignificant effect was evident in reducing daytime sleepiness (Cohen's d = 0.70, p = .08). No significant effects were found on actigraphy markers, depressive symptoms, or tests of cognitive functioning. Conclusions: The eight-week SWTW group intervention for MCI significantly improved subjective sleep quality when compared with a passive control condition. The program also had a moderate (nonsignificant) effect on reducing daytime sleepiness.

Deep learning approaches for automatic detection of sleep apnea events from an electrocardiogram

BACKGROUND AND OBJECTIVE

This study demonstrates deep learning approaches with an aim to find the optimal method to automatically detect sleep apnea (SA) events from an electrocardiogram (ECG) signal.

METHODS

Six deep learning approaches were designed and implemented for automatic detection of SA events including deep neural network (DNN), one-dimensional (1D) convolutional neural networks (CNN), two-dimensional (2D) CNN, recurrent neural networks (RNN), long short-term memory, and gated-recurrent unit (GRU). Designed deep learning models were analyzed and compared in the performances. The ECG signal was pre-processed, normalized, and segmented into 10 s intervals. Subsequently, the signal was converted into a 2D form for analysis in the 2D CNN model. A dataset collected from 86 patients with SA was used. The training set comprised data from 69 of the patients, while the test set contained data from the remaining 17 patients.

RESULTS

The accuracy of the best-performing model was 99.0%, and the 1D CNN and GRU models had 99.0% recall rates.

CONCLUSIONS

The designed deep learning approaches performed better than those developed and tested in previous studies in terms of detecting SA events, and they could distinguish between apnea and hypopnea events using an ECG signal. The deep learning approaches such as 1D CNN and GRU can be helpful tools to automatically detect SA in sleep apnea screening and related studies.

Associations between sleep and verbal memory in subjective cognitive decline: A role for semantic clustering

Age-related reductions in slow wave activity (SWA) and increased fragmentation during sleep play a key role in memory impairment. As the prefrontal cortex is necessary for the control processes relevant to memory encoding, including utilisation of internal heuristics such as semantic clustering, and is preferentially vulnerable to sleep disturbance, our study examined how SWA and sleep fragmentation relates to memory performance in individuals with Subjective Cognitive Decline (SCD). Thirty older adults with SCD (Mean Age = 69.34, SD = 5.34) completed a neurocognitive test battery, including the California Verbal Learning Test, which was used to assess semantic clustering. One week later, participants were admitted to the laboratory for a two night visit. SWA and sleep fragmentation were captured using sleep polysomnography. Next-day memory performance was tested using the Rey Auditory Verbal Learning Test. Poorer sleep (reduced SWA; increased arousals) was associated with reduced semantic clustering, which mediated impairment on verbal memory and learning tests conducted both the day after sleep was recorded (for both SWA and arousals), and a week prior (for arousals only). We demonstrate semantic clustering mediated the well described associations between sleep and verbal memory. As these strategies are a component of cognitive training interventions, future research may examine the role of simultaneous sleep interventions for improving cognitive training outcomes.

Relationships between sleep quality, depressive symptoms and MCI diagnosis: A path analysis

BACKGROUND

This study examined the complex relationships between sleep quality, depressive symptoms, and cognitive decline in older adults. We hypothesised that older age, lower education and greater medical comorbidities would each be associated with increased mild cognitive impairment (MCI) diagnosis risk through indirect effects via poorer sleep quality, and greater depressive symptomology.

METHODS

540 adults 44 years and over were recruited at the Brain and Mind Centre, Sydney, Australia. Participants underwent comprehensive psychiatric, neuropsychological, and medical assessment. Subjective sleep quality, current depressive symptomatology, and current medical burden were assessed.

RESULTS

There were significant indirect effects of each of age, comorbidities and education, that operated via both sleep and depression. Younger age, greater comorbidities and fewer years' education each predicted greater chance of MCI diagnosis via poorer sleep and in turn higher depressive symptomatology. Additionally, there was a significant direct effect of older age on MCI.

LIMITATIONS

The current study is cross-sectional and cannot determine whether poorer sleep quality and greater depressive symptomatology precede or arise as a result of the onset of cognitive decline in later-life. A longitudinal design may allow further explication of these relationships.

CONCLUSIONS

Both sleep and depression are linked with cognitive decline in older adults, with sleep disturbance appearing to predict depressive symptoms. These findings have implications for the management of MCI. Both greater depression symptomatology and sleep disturbance were shown to predict the risk of MCI diagnosis, with this effect strongest in those that are younger. Improved early detection and treatment of sleep problems in older adults may help prevent depressive symptom manifestation or exacerbation, in turn potentially reducing the risk of subsequent cognitive decline.

The prevalence of obstructive sleep apnea in mild cognitive impairment: a systematic review

Background

Previous studies have shown that obstructive sleep apnea (OSA) is associated with a higher risk of cognitive impairment or dementia in the elderly, leading to deleterious health effects and decreasing quality of life. This systematic review aims to determine the prevalence of OSA in patients with mild cognitive impairment (MCI) and examine whether an association between OSA and MCI exists.

Methods

We searched Medline, PubMed, Embase, Cochrane Central, Cochrane Database of Systematic Reviews, PsychINFO, Scopus, the Web of Science, ClinicalTrials.gov and the International Clinical Trials Registry Platform for published and unpublished studies. We included studies in adults with a diagnosis of MCI that reported on the prevalence of OSA. Two independent reviewers performed the abstract and full-text screening, data extraction and the study quality critical appraisal.

Results

Five studies were included in the systematic review. Overall, OSA prevalence rates in patients with MCI varied between 11 and 71% and were influenced by OSA diagnostic methods and patient recruitment locations (community or clinic based). Among studies using the following OSA diagnostic measures– self-report, Home Sleep Apnea Testing, Berlin Questionnaire and polysomnography– the OSA prevalence rates in MCI were 11, 27, 59 and 71%, respectively. In a community-based sample, the prevalence of OSA in patients with and without MCI was 27 and 26%, respectively.

Conclusions

Based on limited evidence, the prevalence of OSA in patients with MCI is 27% and varies based upon OSA diagnostic methods and patient recruitment locations. Our findings provide an important framework for future studies to prospectively investigate the association between OSA and MCI among larger community-based cohorts and implement a standardized approach to diagnose OSA in memory clinics.

PROSPERO registration

CRD42018096577.

Electronic supplementary material

The online version of this article (10.1186/s12883-019-1422-3) contains supplementary material, which is available to authorized users.

Associations between sleep duration and cognitive impairment in mild cognitive impairment

The prevalence of mild cognitive impairment (MCI) increases among elderly people and is associated with a high risk of dementia. Identifying factors that may contribute to the progress of MCI to dementia is critical. The objective of this study was to examine the association of objective sleep with cognitive performance in MCI patients. A subsample of 271 participants with a diagnosis of probable Alzheimer's disease (AD; N = 50) or mild cognitive impairment (MCI; N = 121) and 100 persons who were not cognitively impaired (NI) were recruited from a large population-based cohort in the island of Crete, Greece (3140 older adults aged >60 years). All participants underwent extensive neuropsychiatric/neuropsychological evaluation and a 3-day 24-hr actigraphy. Objective sleep variables and their association with neuropsychological performance were examined across the three groups, controlling for demographics, body mass index, depression, sleep apnea symptoms and psychotropic medications. Patients with AD had significantly longer 24-hr total sleep time (TST) compared to the MCI and NI groups. Long 24-hr TST was associated with reduced performance on tasks that placed significant demands on attention and processing speed in the MCI group and the AD group. Elderly patients with MCI have similar objective sleep duration to normal controls, whereas AD patients sleep longer. Long sleep duration in patients with multidomain subtypes of MCI is associated with critical non-memory cognitive domains. It appears that within the MCI group those that sleep longer have more severe cognitive impairment.

Sex differences in sleep apnea and comorbid neurodegenerative diseases

Sleep apnea is a disorder, which increasingly affects people worldwide. Whether the associated hypoxic events during sleep are central or obstructive in origin, the end result is excessive daytime sleepiness and an increased risk for several comorbidities, such as cardiovascular and neurodegenerative disorders. Sleep apnea is diagnosed more frequently in men than women, suggesting a role of sex hormones in the pathology of the disease. Furthermore, there are sex differences in the development and progression of comorbid diseases associated with sleep apnea. Therefore, treatment of sleep apnea may be clinically relevant for prevention of subsequent sex-specific comorbid disorders. While the impact sleep apnea has on cardiovascular events has been the subject of many research studies, the role of sleep apnea in neurodegeneration is less established. Here we review known risk factors for sleep apnea and the implications of the observed sex differences in this disease. We also summarize the evidence and mechanisms for how sleep apnea may contribute to the onset of neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease.

Sleep and Cognition in Older Adults

Increased age is associated with normative declines in both sleep and cognitive functioning. Although there are some inconsistencies in the literature, negative sleep changes are associated with worse cognitive functioning. This negative relationship holds true across normal-sleeping older adults, older adults with insomnia, older adults with sleep disordered breathing, cognitively healthy older adults, and older adults with dementia. There are mixed results regarding potential benefits of sleep treatments on cognitive functions; however, this line of research deserves added attention because the potential mechanisms of action are likely distinct from other interventions to improve cognition.

Ovarian hormones, sleep and cognition across the adult female lifespan: An integrated perspective

Loss of ovarian function in women is associated with sleep disturbances and cognitive decline, which suggest a key role for estrogens and/or progestins in modulating these symptoms. The effects of ovarian hormones on sleep and cognitive processes have been studied in separate research fields that seldom intersect. However, sleep has a considerable impact on cognitive function. Given the tight connections between sleep and cognition, ovarian hormones may influence selective aspects of cognition indirectly, via the modulation of sleep. In support of this hypothesis, a growing body of evidence indicates that the development of sleep disorders following menopause contributes to accelerated cognitive decline and dementia in older women. This paper draws from both the animal and human literature to present an integrated view of the effects of ovarian hormones on sleep and cognition across the adult female lifespan.

Poor sleep quality is observed in mild cognitive impairment and is largely unrelated to depression and anxiety

BACKGROUND

Individuals with mild cognitive impairment (MCI) commonly experience a number of sleep quality related issues. However, it remains unclear if these issues are specific to MCI or are simply attributed to the elevated levels depression and anxiety symptoms frequently observed among those with MCI. The present study sought to examine group differences between participants with MCI and matched controls on self-reported measures of sleep quality while controlling for depression and anxiety levels.

METHODS

Participants with MCI (N = 48) and demographically matched controls (N = 48) were administered with self-reported measures of anxiety, depression and sleep quality. Sleep quality between both groups were first analyzed using a Multivariate Analysis of Variance, and then subsequently a Multivariate Analysis of Covariance incorporating depression and anxiety scores as covariates.

RESULTS

The MCI group had significantly higher levels of depression and anxiety than the controls. On the sleep-related measures, the MCI group had significantly worse outcomes in sleep duration, disturbances, latency, efficiency, quality and daytime dysfunction. After controlling for depression and anxiety levels, with the exception of daytime dysfunction, all other differences remain significant, and are also associated with moderate to large effect sizes.

CONCLUSION

The results suggest that sleep quality issues are present in MCI and are largely independent of depression and anxiety.

Role of Sleep Disturbance in the Trajectory of Alzheimer's Disease

Sleep disturbances such as insomnia, hypersomnia, and circadian rhythm disturbance are common in normal elderly and Alzheimer’s disease (AD) patients. To date, special attention has been paid to sleep disturbance in the clinical course of AD insofar as the interaction of sleep disturbance with the pathogenesis of AD may impact the clinical course and cognitive function of AD patients. This review covers the bidirectional relationship between sleep disturbance and AD pathogenesis; the associations between sleep disturbance and AD-specific neurotransmitters, brain structure, and aspects of sleep disturbance in each phase of AD; and the effects of sleep disturbance on the cognitive functions of patients in each phase of AD. We consider several factors required to exactly interpret the results and suggest a direction for future studies on the role of sleep disturbance in AD.

Is Obstructive Sleep Apnoea Related to Neuropsychological Function in Healthy Older Adults? A Systematic Review and Meta-Analysis

Previous systematic reviews and meta-analyses have identified cognitive deficits in adults with obstructive sleep apnoea (OSA). However, quantitative analysis of the association between OSA and neuropsychological performance has not been conducted specifically in older adults, for whom there is a greater risk of cognitive decline. We searched Medline, Embase and PsycINFO through August 2016 for studies describing associations between OSA and neuropsychological outcomes in people aged>50 years. Meta-analyses were performed on these studies for overall cognition and within cognitive domains. Subgroup analyses were performed taking into account risk of bias and moderating differences in study design. 13 studies met eligibility criteria for analysis. A small negative association was found between OSA and all neuropsychological outcomes combined, g=0.18(95% CI 0.04-0.32), and in memory and processing speed domains. Small case-control studies from sleep clinic populations observed the greatest associations, while larger cohort studies from community samples illustrated no association. Analysis accounting for publication bias resulted in a null overall association, g=0.02 (95%CI -0.12 to 0.16). Associations between OSA and cognition in later life are highly variable and the findings differ based on the type and setting of study. It appears some older adults may be at risk of cognitive impairments attributable to OSA; however, the risk of bias renders the evidence inconclusive. High quality research is warranted in clinically diagnosed OSA patients as well as those already experiencing neuropsychological impairment and who may be regarded at higher risk of further cognitive decline.

Associations of sleep disturbance with physical function and cognition in older adults with cancer

PURPOSE

Although sleep disturbances are common in older adults, studies evaluating the prevalence of sleep disturbance and its influence on functional outcomes in older adults with cancer are few. In this study, we examined the prevalence of sleep disturbance and its association with physical function and cognition in older adults with cancer.

METHODS

This is a cross-sectional study of patients who were referred and evaluated in the Specialized Oncology Care & Research in the Elderly (SOCARE) clinics at the Universities of Rochester and Chicago from May 2011 to October 2015. All patients underwent a geriatric assessment (GA) as part of their routine evaluation. Our final study cohort included patients who completed a sleep assessment and consented to the study. We collected demographics (age, sex, race, marital status, and education level) and clinical characteristics (depression, comorbidity, cancer type, and stage) from the GA and medical chart reviews. Presence of sleep disturbance was self-reported (yes/no). Physical function was assessed using Instrumental Activities of Daily Living (IADLs), physical activity (PA) survey, falls in the preceding 6 months, and Short Physical Performance Battery (SPPB). Cognition was screened using the Blessed Orientation-Memory-Concentration Test (impairment >4) or Montreal Cognitive Assessment (impairment <26). Bivariate and multivariable analyses were used to examine the associations between sleep disturbance with functional outcomes and cognition.

RESULTS

We included 389 older patients. The prevalence of sleep disturbance was 40%. Sixty-eight percent had ≥1 IADL impairment, 76% had PA limitation, 37% had ≥1 fall, 70% had impairment on SPPB, and 47% screened positive for cognitive impairment. On bivariate analyses, sleep disturbance was associated with IADL impairment (odds ratio [OR] 1.96, 95% confidence interval [CI] 1.23-3.13, P = 0.005), and PA limitation (OR 2.43, 95% CI 1.38-4.28, P = 0.002). The associations remained significant on multivariable analyses. Sleep disturbance was not significantly associated with falls, impairment on SPPB, and performance on the cognitive screen.

CONCLUSION

Sleep disturbance was associated with IADL impairment and PA limitation. It is important for oncologists to inquire about sleep problems, and these patients should also be screened for functional impairment if sleep disturbance was present.

Detrending Changes the Temporal Dynamics of a Semantic Fluency Task

Objective: To study the dynamics of clustering semantic fluency responses and switching between clusters. Methods: We conducted a cross-sectional study of participants (N = 60) in a study of patient reported outcomes who were given the Saint Louis University Mental Status test. Sixty-second animal naming tests were scored for the timing of responses as well as the clustering of responses into semantic categories. Time scores were detrended to correct for exponential exhaustion and normalize the time scale across individuals. Results: Grouped by number of responses given, low performers (LP; Carter et al., 2012) switched between clusters fewer times than medium performers (MP) and high performers (HP). Prior to detrending, LP showed increased intracluster response times when compared to the other groups, but no differences were shown in intercluster response times. After detrending, however, the difference in intracluster response times disappeared and LP showed significantly faster detrended intercluster response times compared to both MP and HP. Conclusion: Prior to detrending, slower intracluster response times appear to be driving poorer performance. When time scores are detrended, our findings suggest that LP participants have quicker intercluster response times but exhaust more quickly as well. Detrending can help describe the interplay between the structure-loss and retrieval-slowing models of declining semantic fluency by isolating the component mechanisms involved in each.

Longitudinal association of delta activity at sleep onset with cognitive and affective function in community-dwelling older adults

OBJECTIVE

This investigation sought to determine whether delta activity at sleep onset (DASO) in the sleep electroencephalography of older adults represents normal variation or is associated with clinical pathology. To this end, we examined its longitudinal associations with cognitive and affective function in older adults without dementia.

METHODS

Participants were 153 community-dwelling older adults without dementia. We evaluated polysomnography (PSG), cognitive performance, and affective function at four time points: baseline, 12, 24, and 36 months. All participants completed PSG and measures of global cognition, delayed verbal memory, information processing speed, attention, inhibition, verbal naming, visuospatial ability, and measures of anxiety and depression. DASO was defined as sequences of rhythmic anterior delta activity on PSG in the transition from awake to sleep during the baseline assessment (Figure ).

RESULTS

At the baseline, 83 women and 70 men, mean age 71.3 ± 0.6 years participated and 19.6% of participants exhibited DASO. Age, years of education, gender, and body mass index did not differ according to DASO status. Linear mixed modeling showed that the presence of DASO was actually associated with lower levels of anxiety and depression. Further, participants with DASO, versus those without DASO, exhibited a trend towards better cognitive performance over time, although none of these associations reached statistical significance.

CONCLUSIONS

Whereas DASO was associated with better affective function, no significant association was found between DASO and cognitive change over time. These longitudinal findings support the view that the presence of DASO in healthy older adults represents normal variation rather than pathological aging. Copyright © 2016 John Wiley & Sons, Ltd.

Cognitive impairment before changes appear on [18F]-fluoro-D-glucose positron emission tomography images in a patient with possible early-stage cerebellar-predominant multiple system atrophy

Multiple system atrophy (MSA) is a sporadic, rapidly progressive neurodegenerative disorder characterized by autonomic dysfunction combined with parkinsonism or cerebellar ataxia. Patients with MSA typically suffer from cognitive disorders and rapid eye movement sleep behaviour disorder. ¹⁸ F-fluorodeoxyglucose-positron emission tomography is used to assess MSA. However, the relationship between the clinical features and findings on ¹⁸ F-fluorodeoxyglucose-positron emission tomography in patients with MSA has not yet been investigated. Here we report a case of possible early-stage cerebellar-type MSA. We concluded that cerebellar-type MSA or other factors, such as rapid eye movement sleep behaviour disorder or obstructive sleep apnoea cognitive impairment, could appear before changes are visible on ¹⁸ F-fluorodeoxyglucose-positron emission tomography images. Additionally, we concluded that the cognitive impairment could derive from cerebellar-type MSA itself, not from other factors such as rapid eye movement sleep behaviour disorder or sleep apnoea syndrome.

Effect of CPAP therapy on C-reactive protein and cognitive impairment in patients with obstructive sleep apnea hypopnea syndrome

PURPOSE

Obstructive sleep apnea hypopnea syndrome (OSAHS) is associated with neurocognitive impairment. We examined the role of the systemic inflammatory response, measured by high-sensitivity C-reactive protein (hsCRP) assay, and the effect of CPAP treatment on hsCRP and cognitive impairment in patients with OSAHS.

METHODS

Eligible subjects (n = 178) were categorized into two groups: absent or mild OSAHS, and moderate to severe OSAHS. First, the Montreal Cognitive Assessment (MoCA) and serum hsCRP concentration were measured. Then, the moderate to severe OSAHS group was further divided into a conservative treatment subgroup (n = 68) and a CPAP subgroup (n = 68). After 6 months of treatment, MoCA scores and hsCRP concentrations were re-measured in the moderate to severe group.

RESULTS

Compared with the absent or mild OSAHS group, hsCRP concentration was higher (1.00 ± 1.28 mg/L versus 2.71 ± 1.8, p < 0.001) and MoCA scores were significantly lower (27.4 ± 1.4 versus 26.3 ± 2.0, p < 0.001) in the moderate to severe group. After adjustment for age, education, body mass index, and neck circumference, hsCRP and MoCA scores correlated with parameters of overnight hypoxia. hsCRP and the proportion of time spent with blood oxygen saturation < 90 % (T90) predicted MoCA score. hsCRP and MoCA score improved, and the subdomains of the MoCA were partially improved, in the CPAP treatment subgroup. In conservatively managed patients, hsCRP concentration increased, and there was no improvement in neurocognitive dysfunction, with the memory subdomain significantly worse.

CONCLUSIONS

hsCRP may play a role in neurocognitive dysfunction in OSAHS. Long-term CPAP treatment could normalize the serum hsCRP concentration and partially reverse cognitive dysfunction in OSAHS.

The Role of Sleep and Sleep Disorders in the Development, Diagnosis, and Management of Neurocognitive Disorders

It is becoming increasingly apparent that sleep plays an important role in the maintenance, disease prevention, repair, and restoration of both mind and body. The sleep and wake cycles are controlled by the pacemaker activity of the superchiasmic nucleus in the hypothalamus but can be disrupted by diseases of the nervous system causing disordered sleep. A lack of sleep has been associated with an increase in all-cause mortality. Likewise, sleep disturbances and sleep disorders may disrupt neuronal pathways and have an impact on neurological diseases. Sleep deprivation studies in normal subjects demonstrate that a lack of sleep can cause attention and working memory impairment. Moreover, untreated sleep disturbances and sleep disorders such as obstructive sleep apnoe (OSA) can also lead to cognitive impairment. Poor sleep and sleep disorders may present a significant risk factor for the development of dementia. In this review, the underlying mechanisms and the role of sleep and sleep disorders in the development of neurocognitive disorders [dementia and mild cognitive impairment (MCI)] and how the presence of sleep disorders could direct the process of diagnosis and management of neurocognitive disorders will be discussed.