Sleep apnea and the risk of dementia: A systematic review and meta-analysis

Cerebral perfusion is not impaired in persons with moderate obstructive sleep apnoea when awake

PURPOSE

It is well established that, together with a multitude of other adverse effects on health, severe obstructive sleep apnoea causes reduced cerebral perfusion and, in turn, reduced cerebral function. Less clear is the impact of moderate obstructive sleep apnoea (OSA). Our aim was to determine if cerebral blood flow is impaired in people diagnosed with moderate OSA.

METHODS

Twenty-four patients diagnosed with moderate OSA (15 ≤ apnoea-hypopnea index (AHI) < 30) were recruited (aged 32-72, median 59 years, 10 female). Seven controls (aged 42-73 years, median 62 years, 4 female) with an AHI < 5 were also recruited. The OSA status of all participants was confirmed at baseline by unattended polysomnography and they had an MRI arterial-spin-labelling scan of cerebral perfusion.

RESULTS

Neither global perfusion nor voxel-wise perfusion differed significantly between the moderate-OSA and control groups. We also compared the average perfusion across three regional clusters, which had been found in a previous study to have significant perfusion differences with moderate-severe OSA versus control, and found no significant difference in perfusion between the two groups. The perfusions were also very close, with means of 50.2 and 51.8 mL/100 g/min for the moderate-OSAs and controls, respectively, with a negligible effect size (Cohen's d = 0.10).

CONCLUSION

We conclude that cerebral perfusion is not impaired in people with moderate OSA and that cerebral flow regulatory mechanisms can cope with the adverse effects which occur in moderate OSA. This is an important factor in clinical decisions for prescription of continuous positive airway pressure therapy (CPAP).

Specific and cumulative infection burden and mild cognitive impairment and dementia: A population-based study

Infection by pathogenic microbes is widely hypothesized to be a risk factor for the development of neurocognitive disorders and dementia, but evidence remains limited. We analyzed the association of seropositivity to 11 common pathogens and cumulative infection burden with neurocognitive disorder (mild cognitive impairment and dementia) in a population-based cohort of 475 older individuals (mean age = 67.6 y) followed up over 3-5 years for the risk of MCI-dementia. Specific seropositivities showed a preponderance of positive trends of association with MCI-dementia, including for Plasmodium, H. pylori, and RSV (p < 0.05), as well as Chickungunya, HSV-2, CMV and EBV (p > 0.05), while HSV-1 and HHV-6 showed equivocal or no associations, and Dengue and VZV showed negative associations (p < 0.05) with MCI-dementia. High infection burden (5 + cumulated infections) was significantly associated with an increased MCI-dementia risk in comparison with low infection burden (1-3 cumulative infections), adjusted for age, sex, and education. Intriguingly, for a majority (8 of 11) of pathogens, levels of antibody titers were significantly lower in those with MCI-dementia compared to cognitive normal individuals. Based on our observations, we postulate that individuals who are unable to mount strong immunological responses to infection by diverse microorganisms, and therefore more vulnerable to infection by greater numbers of different microbial pathogens or repeated infections to the same pathogen in the course of their lifetime are more likely to develop MCI or dementia. This hypothesis should be tested in more studies.

Analysis of sleep apnea research with a special focus on the use of positron emission tomography as a study tool

The quality of sleep plays a significant role in determining human well-being, and studying sleep and sleep disorders using various methods can aid in the prevention and treatment of diseases. Positron emission tomography (PET) is a noninvasive and highly sensitive medical imaging technique that has been widely adopted in the clinic. This review article provides data on research activity related to sleep and sleep apnea and discusses the use of PET in investigating sleep apnea and other sleep disorders. We conducted a statistical analysis of the number of original research articles published on sleep and sleep apnea between 1965 and 2021 and found that there has been a dramatic increase in publications since 1990. The distribution of contributing countries and regions has also undergone significant changes. Although there is an extensive body of literature on sleep research (256,399 original research articles during 1965-2021), PET has only been used in 54 of these published studies, indicating a largely untapped area of research. Nonetheless, PET is a useful tool for identifying connections between sleep disorders and pathological changes in various diseases, including neurological, metabolic, and cardiovascular disorders, as well as cancer. To facilitate the broader use of PET in sleep apnea research, further studies are needed in both clinical and preclinical settings.

The Cost-Effectiveness of Sleep Apnea Management: A Critical Evaluation of the Impact of Therapy on Health Care Costs

TOPIC IMPORTANCE

OSA is a widespread condition that significantly affects both health and health-related quality of life (HRQoL). If left untreated, OSA can lead to accidents, decreased productivity, and medical complications, resulting in significant economic burdens including the direct costs of managing the disorder. Given the constraints on health care resources, understanding the cost-effectiveness of OSA management is crucial. A key factor in cost-effectiveness is whether OSA therapies reduce medical costs associated with OSA-related complications.

REVIEW FINDINGS

Treatments for OSA have been shown to enhance HRQoL, particularly for symptomatic patients with moderate or severe disease. Economic studies also have demonstrated that these treatments are highly cost-effective. However, although substantial empirical evidence shows that untreated OSA is associated with increased medical costs, uncertainty remains about the impact of OSA treatment on these costs. Randomized controlled trials of positive airway pressure (PAP) therapy have failed to demonstrate cost reductions, but the studies have had important limitations. Observational studies suggest that PAP therapy may temper increases in costs, but only among patients who are highly adherent to treatment. However, the healthy adherer effect is an important potential source of bias in these studies.

SUMMARY

OSA management is cost-effective, although uncertainties persist regarding the therapy's impact on medical costs. Future studies should focus on reducing bias, particularly the healthy adherer effect, and addressing other confounding factors to clarify potential medical cost savings. Promising avenues to further understanding include using quasiexperimental designs, incorporating more sophisticated characterization of OSA severity and symptoms, and leveraging newer technologies (eg, big data, wearables, and artificial intelligence).

The role of cardiovascular health and vascular events in the relationship between excessive daytime sleepiness and dementia risk

Many studies suggest a relationship between excessive daytime sleepiness (EDS) and dementia incidence, but the underlying mechanisms remain uncertain. The study aimed to investigate the role of cardiovascular burden in the relationship between EDS and dementia incidence over a 12-year follow-up in community-dwelling older adults. We performed analyses on 6171 subjects (aged ≥65 years) free of dementia and vascular disease at baseline. Participants self-reported EDS at baseline and an expert committee validated both prevalent and incident dementia. We defined cardiovascular burden by a low Cardiovascular Health score, constructed using the American Heart Association metrics, and incident vascular events. To explore the potential role of the cardiovascular burden in the relationship between EDS and dementia, we conducted mediation analyses with inverse odds ratio-weighted estimation, using multivariable-adjusted proportional hazard Cox and logistic regression models. Subjects with EDS had a higher risk of all-cause dementia (hazard ratio [HR] 1.39, 95% confidence interval [CI] 1.13-1.69) and dementia with vascular component (DVC) (HR 2.14, 95% CI 1.30-3.51), but not Alzheimer's disease (HR 1.18, 95% CI 0.93-1.51). Cardiovascular burden explained 5% (95% CI 4.1-5.2) and 11% (95% CI 9.7-11.3) of the relationship between EDS and all-cause dementia and DVC, respectively. These findings confirm that EDS may be implicated in the development of dementia and indicate a weaker than expected role of cardiovascular burden in the relationship between EDS and DVC.

The effect of pharyngeal structures on the severity of obstructive sleep apnea

BACKGROUND/OBJECTIVE

Obstructive sleep apnea (OSA) is characterized by complete or partial cessation of breathing during sleep. The tongue is suggested as a possible anatomical site causing airway obstruction. However, the role of other pharyngeal structures in the development of OSA remains unclear. We designed a study using both the apnea-hypopnea index (AHI) and the oxygen saturation measurements to assess the severity of OSA. We aimed to identify critical anatomical structures of the upper airway that correlate with the severity of OSA and to evaluate the utility of magnetic resonance imaging (MRI) markers to detect possible OSA in patients without overt symptoms.

MATERIALS AND METHODS

The study included participants referred to the neurology outpatient clinic from the check-up unit. Participants were grouped as controls, mild, moderate, or severe OSA according to the AHI. A cranial MRI with a field of view (FOV) encompassing the upper airway structures was obtained from all participants. The areas of the tongue and the uvula were measured on the sagittal images by drawing the boundaries of the tissues manually. The posterior air space (PAS) area was evaluated from regions of interest in five parallel planes.

RESULTS

Of 105 participants, 30 were controls, 27 had mild, 25 had moderate, and 23 had severe OSA. The moderate and severe OSA groups did not differ in oxygen saturation levels during sleep. Therefore, patients with moderate and severe OSA were combined into one group (moderate/severe OSA). The area of the tongue was significantly larger in the moderate/severe OSA group compared to the control group. Both the tongue and the uvula areas showed a significant positive correlation with the AHI.

CONCLUSION

Our findings suggest that the tongue and uvula have prominent roles in the severity of OSAS. It may be useful to measure these structures with MRI to screen for at-risk individuals without overt OSA symptoms.

Prospective cohort study of long-term neurological outcomes in retired elite athletes: the Advanced BiomaRker, Advanced Imaging and Neurocognitive (BRAIN) Health Study protocol

INTRODUCTION

Although limited, recent research suggests that contact sport participation might have an adverse long-term effect on brain health. Further work is required to determine whether this includes an increased risk of neurodegenerative disease and/or subsequent changes in cognition and behaviour. The Advanced BiomaRker, Advanced Imaging and Neurocognitive Health Study will prospectively examine the neurological, psychiatric, psychological and general health of retired elite-level rugby union and association football/soccer players.

METHODS AND ANALYSIS

400 retired athletes will be recruited (200 rugby union and 200 association football players, male and female). Athletes will undergo a detailed clinical assessment, advanced neuroimaging, blood testing for a range of brain health outcomes and neuropsychological assessment longitudinally. Follow-up assessments will be completed at 2 and 4 years after baseline visit. 60 healthy volunteers will be recruited and undergo an aligned assessment protocol including advanced neuroimaging, blood testing and neuropsychological assessment. We will describe the previous exposure to head injuries across the cohort and investigate relationships between biomarkers of brain injury and clinical outcomes including cognitive performance, clinical diagnoses and psychiatric symptom burden.

ETHICS AND DISSEMINATION

Relevant ethical approvals have been granted by the Camberwell St Giles Research Ethics Committee (Ref: 17/LO/2066). The study findings will be disseminated through manuscripts in clinical/academic journals, presentations at professional conferences and through participant and stakeholder communications.

Clinical Outcomes and Tau Pathology in Retired Football Players: Associations With Diagnosed and Witnessed Sleep Apnea

Background and Objectives

Obstructive sleep apnea (SA) is common in older men and a contributor to negative cognitive, psychiatric, and brain health outcomes. Little is known about SA in those who played contact sports and are at increased risk of neurodegenerative disease(s) and other neuropathologies associated with repetitive head impacts (RHI). In this study, we investigated the frequency of diagnosed and witnessed SA and its contribution to clinical symptoms and tau pathology using PET imaging among male former college and former professional American football players.

Methods

The sample included 120 former National Football League (NFL) players, 60 former college players, and 60 asymptomatic men without exposure to RHI (i.e., controls). Diagnosed SA was self-reported, and all participants completed the Mayo Sleep Questionnaire (MSQ, informant version), the Epworth Sleepiness Scale (ESS), neuropsychological testing, and tau (flortaucipir) PET imaging. Associations between sleep indices (diagnosed SA, MSQ items, and the ESS) and derived neuropsychological factor scores, self-reported depression (Beck Depression Inventory-II [BDI-II]), informant-reported neurobehavioral dysregulation (Behavior Rating Inventory of Executive Function-Adult Version [BRIEF-A] Behavioral Regulation Index [BRI]), and tau PET uptake, were tested.

Results

Approximately 36.7% of NFL players had diagnosed SA compared with 30% of the former college football players and 16.7% of the controls. Former NFL players and college football players also had higher ESS scores compared with the controls. Years of football play was not associated with any of the sleep metrics. Among the former NFL players, diagnosed SA was associated with worse Executive Function and Psychomotor Speed factor scores, greater BDI-II scores, and higher flortaucipir PET standard uptake value ratios, independent of age, race, body mass index, and APOE ε4 gene carrier status. Higher ESS scores correlated with higher BDI-II and BRIEF-A BRI scores. Continuous positive airway pressure use mitigated all of the abovementioned associations. Among the former college football players, witnessed apnea and higher ESS scores were associated with higher BRIEF-A BRI and BDI-II scores, respectively. No other associations were observed in this subgroup.

Discussion

Former elite American football players are at risk of SA. Our findings suggest that SA might contribute to cognitive, neuropsychiatric, and tau outcomes in this population. Like all neurodegenerative diseases, this study emphasizes the multifactorial contributions to negative brain health outcomes and the importance of sleep for optimal brain health.

Associations of sleep disorders with all-cause MCI/dementia and different types of dementia - clinical evidence, potential pathomechanisms and treatment options: A narrative review

Due to worldwide demographic change, the number of older persons in the population is increasing. Aging is accompanied by changes of sleep structure, deposition of beta-amyloid (Aß) and tau proteins and vascular changes and can turn into mild cognitive impairment (MCI) as well as dementia. Sleep disorders are discussed both as a risk factor for and as a consequence of MCI/dementia. Cross-sectional and longitudinal population-based as well as case-control studies revealed sleep disorders, especially sleep-disorderded breathing (SDB) and excessive or insufficient sleep durations, as risk factors for all-cause MCI/dementia. Regarding different dementia types, SDB was especially associated with vascular dementia while insomnia/insufficient sleep was related to an increased risk of Alzheimer's disease (AD). Scarce and still inconsistent evidence suggests that therapy of sleep disorders, especially continuous positive airway pressure (CPAP) in SDB, can improve cognition in patients with sleep disorders with and without comorbid dementia and delay onset of MCI/dementia in patients with sleep disorders without previous cognitive impairment. Regarding potential pathomechanisms via which sleep disorders lead to MCI/dementia, disturbed sleep, chronic sleep deficit and SDB can impair glymphatic clearance of beta-amyloid (Aß) and tau which lead to amyloid deposition and tau aggregation resulting in changes of brain structures responsible for cognition. Orexins are discussed to modulate sleep and Aß pathology. Their diurnal fluctuation is suppressed by sleep fragmentation and the expression suppressed at the point of hippocampal atrophy, contributing to the progression of dementia. Additionally, sleep disorders can lead to an increased vascular risk profile and vascular changes such as inflammation, endothelial dysfunction and atherosclerosis which can foster neurodegenerative pathology. There is ample evidence indicating that changes of sleep structure in aging persons can lead to dementia and also evidence that therapy of sleep disorder can improve cognition. Therefore, sleep disorders should be identified and treated early.

Impact of Sleep Disorders and Disturbed Sleep on Brain Health: A Scientific Statement From the American Heart Association

Accumulating evidence supports a link between sleep disorders, disturbed sleep, and adverse brain health, ranging from stroke to subclinical cerebrovascular disease to cognitive outcomes, including the development of Alzheimer disease and Alzheimer disease-related dementias. Sleep disorders such as sleep-disordered breathing (eg, obstructive sleep apnea), and other sleep disturbances, as well, some of which are also considered sleep disorders (eg, insomnia, sleep fragmentation, circadian rhythm disorders, and extreme sleep duration), have been associated with adverse brain health. Understanding the causal role of sleep disorders and disturbances in the development of adverse brain health is complicated by the common development of sleep disorders among individuals with neurodegenerative disease. In addition to the role of sleep disorders in stroke and cerebrovascular injury, mechanistic hypotheses linking sleep with brain health and biomarker data (blood-based, cerebrospinal fluid-based, and imaging) suggest direct links to Alzheimer disease-specific pathology. These potential mechanisms and the increasing understanding of the "glymphatic system," and the recognition of the importance of sleep in poststroke recovery, as well, support a biological basis for the indirect (through the worsening of vascular disease) and direct (through specific effects on neuropathology) connections between sleep disorders and brain health. Given promising evidence for the benefits of treatment and prevention, sleep disorders and disturbances represent potential targets for early treatment that may improve brain health more broadly. In this scientific statement, we discuss the evidence supporting an association between sleep disorders and disturbances and poor brain health ranging from stroke to dementia and opportunities for prevention and early treatment.

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.

Shedding light on neurofilament involvement in cognitive decline in obstructive sleep apnea and its possible role as a biomarker

Obstructive sleep apnea is one of the most common sleep disorders with a high estimated global prevalence and a large number of associated comorbidities in general as well as specific neuropsychiatric complications such as cognitive impairment. The complex pathogenesis and effects of the disorder including chronic intermittent hypoxia and sleep fragmentation may lead to enhanced neuronal damage, thereby contributing to neuropsychiatric pathologies. Obstructive sleep apnea has been described as an independent risk factor for several neurodegenerative diseases, including Alzheimer's disease and all-cause dementia. The influence of obstructive sleep apnea on cognitive deficits is still a topic of recent debate, and several mechanisms, including neurodegeneration and depression-related cognitive dysfunction, underlying this correlation are taken into consideration. The differentiation between both pathomechanisms of cognitive impairment in obstructive sleep apnea is a complex clinical issue, requiring the use of multiple and costly diagnostic methods. The studies conducted on neuroprotection biomarkers, such as brain-derived neurotrophic factors and neurofilaments, are recently gaining ground in the topic of cognition assessment in obstructive sleep apnea patients. Neurofilaments as neuron-specific cytoskeletal proteins could be useful non-invasive indicators of brain conditions and neurodegeneration, which already are observed in many neurological diseases leading to cognitive deficits. Additionally, neurofilaments play an important role as a biomarker in other sleep disorders such as insomnia. Thus, this review summarizes the current knowledge on the involvement of neurofilaments in cognitive decline and neurodegeneration in obstructive sleep apnea patients as well as discusses its possible role as a biomarker of these changes.

Sleep Disorders in Patients with Neurologic Disease

OBJECTIVE

This article provides an overview of the growing body of evidence showing bidirectional relationships between sleep and various neurologic disorders.

LATEST DEVELOPMENTS

Mounting evidence demonstrates that disrupted sleep can negatively impact various neurologic disease processes, including stroke, multiple sclerosis, epilepsy, neuromuscular disorders including amyotrophic lateral sclerosis, and headache syndromes. Abnormal sleep can also be a precursor to Alzheimer disease and neurodegenerative disease states such as Parkinson disease and dementia with Lewy bodies. Interventions to improve sleep and treat obstructive sleep apnea may play a vital role in preventing neurologic disease development and progression.

ESSENTIAL POINTS

Sleep disorders are common among patients with neurologic disorders. To provide comprehensive care to patients with neurologic conditions, neurologists must ask patients about sleep issues that may warrant further diagnostic testing, treatment, and sleep medicine referral when indicated.

Examining later-in-life health risks associated with sport-related concussion and repetitive head impacts: a systematic review of case-control and cohort studies

OBJECTIVE

Concern exists about possible problems with later-in-life brain health, such as cognitive impairment, mental health problems and neurological diseases, in former athletes. We examined the future risk for adverse health effects associated with sport-related concussion, or exposure to repetitive head impacts, in former athletes.

DESIGN

Systematic review.

DATA SOURCES

Search of MEDLINE, Embase, Cochrane, CINAHL Plus and SPORTDiscus in October 2019 and updated in March 2022.

ELIGIBILITY CRITERIA

Studies measuring future risk (cohort studies) or approximating that risk (case-control studies).

RESULTS

Ten studies of former amateur athletes and 18 studies of former professional athletes were included. No postmortem neuropathology studies or neuroimaging studies met criteria for inclusion. Depression was examined in five studies in former amateur athletes, none identifying an increased risk. Nine studies examined suicidality or suicide as a manner of death, and none found an association with increased risk. Some studies comparing professional athletes with the general population reported associations between sports participation and dementia or amyotrophic lateral sclerosis (ALS) as a cause of death. Most did not control for potential confounding factors (eg, genetic, demographic, health-related or environmental), were ecological in design and had high risk of bias.

CONCLUSION

Evidence does not support an increased risk of mental health or neurological diseases in former amateur athletes with exposure to repetitive head impacts. Some studies in former professional athletes suggest an increased risk of neurological disorders such as ALS and dementia; these findings need to be confirmed in higher quality studies with better control of confounding factors.

PROSPERO REGISTRATION NUMBER

CRD42022159486.

Consensus statement on concussion in sport: the 6th International Conference on Concussion in Sport-Amsterdam, October 2022

For over two decades, the Concussion in Sport Group has held meetings and developed five international statements on concussion in sport. This 6th statement summarises the processes and outcomes of the 6th International Conference on Concussion in Sport held in Amsterdam on 27-30 October 2022 and should be read in conjunction with the (1) methodology paper that outlines the consensus process in detail and (2) 10 systematic reviews that informed the conference outcomes. Over 3½ years, author groups conducted systematic reviews of predetermined priority topics relevant to concussion in sport. The format of the conference, expert panel meetings and workshops to revise or develop new clinical assessment tools, as described in the methodology paper, evolved from previous consensus meetings with several new components. Apart from this consensus statement, the conference process yielded revised tools including the Concussion Recognition Tool-6 (CRT6) and Sport Concussion Assessment Tool-6 (SCAT6, Child SCAT6), as well as a new tool, the Sport Concussion Office Assessment Tool-6 (SCOAT6, Child SCOAT6). This consensus process also integrated new features including a focus on the para athlete, the athlete's perspective, concussion-specific medical ethics and matters related to both athlete retirement and the potential long-term effects of SRC, including neurodegenerative disease. This statement summarises evidence-informed principles of concussion prevention, assessment and management, and emphasises those areas requiring more research.

The effect of sleep disorders on dementia risk in patients with traumatic brain injury: A large-scale cohort study

Introduction

We investigated the association between sleep disorders (SDs) and incident dementia in adults with traumatic brain injury (TBI).

Methods

Adults with a TBI between 2003 and 2013 were followed until incident dementia. Sleep disorders at TBI were predictors in Cox regression models, controlling for other dementia risks.

Results

Over 52 months, 4.6% of the 712,708 adults (59% male, median age 44, <1% with SD) developed dementia. An SD was associated with a 26% and a 23% of increased risk of dementia in male and female participants (hazard ratio [HR] 1.26, 95% confidence interval [CI] 1.11-1.42 and HR 1.23, 95% CI 1.09-1.40, respectively). In male participants, SD was associated with a 93% increased risk of early-onset dementia (HR 1.93, 95% CI 1.29-2.87); this did not hold in female participants (HR 1.38, 95% CI 0.78-2.44).

Discussion

In a province-wide cohort, SDs at TBI were independently associated with incident dementia. Clinical trials testing sex-specific SD care after TBI for dementia prevention are timely.

Highlights

TBI and sleep disorders are linked to each other, and to dementia.It is unclear if sleep disorders pose a sex-specific dementia risk in brain injury.In this study, presence of a sleep disorder increased dementia risk in both sexes.The risk differed by type of sleep disorder, which differed between the sexes.Sleep disorder awareness and care in persons with brain injury is vital for dementia prevention.

An Alternative View of Familial Alzheimer's Disease Genetics

Probabilistic and parsimony-based arguments regarding available genetics data are used to propose that Hardy and Higgin's amyloid cascade hypothesis is valid but is commonly interpreted too narrowly to support, incorrectly, the primacy of the amyloid-β peptide (Aβ) in driving Alzheimer's disease pathogenesis. Instead, increased activity of the βCTF (C99) fragment of AβPP is the critical pathogenic determinant altered by mutations in the APP gene. This model is consistent with the regulation of APP mRNA translation via its 5' iron responsive element. Similar arguments support that the pathological effects of familial Alzheimer's disease mutations in the genes PSEN1 and PSEN2 are not exerted directly via changes in AβPP cleavage to produce different ratios of Aβ length. Rather, these mutations likely act through effects on presenilin holoprotein conformation and function, and possibly the formation and stability of multimers of presenilin holoprotein and/or of the γ-secretase complex. All fAD mutations in APP, PSEN1, and PSEN2 likely find unity of pathological mechanism in their actions on endolysosomal acidification and mitochondrial function, with detrimental effects on iron homeostasis and promotion of "pseudo-hypoxia" being of central importance. Aβ production is enhanced and distorted by oxidative stress and accumulates due to decreased lysosomal function. It may act as a disease-associated molecular pattern enhancing oxidative stress-driven neuroinflammation during the cognitive phase of the disease.

Association of a History of Sleep Disorder With Risk of Mild Cognitive Impairment and Alzheimer's Disease Dementia

OBJECTIVE

We explored whether a history of sleep disorder affected a current diagnosis of cognitive impairment and clinical conversion in a non-demented elderly population.

METHODS

Comprehensive clinical data collected as part of the Alzheimer's Disease Neuroimaging Initiative (ADNI) was analyzed. A history of sleep disorder was recorded in the recent ADNI medical database. Standard clinical and neuropsychological tests were performed both at baseline and follow-up visit. Multiple logistic regression analysis was performed after adjusting for age, sex, education, apolipoprotein E ε4 status, vascular risk score, body mass index, Geriatric Depression Scale score, and use of sleeping pills.

RESULTS

A total of 391 cognitively normal individuals, 303 with early mild cognitive impairment (MCI) and 364 with late MCI were included. Sleep disorder history was significantly associated with an increased risk of MCI but not with clinical conversion. A history of insomnia or obstructive sleep apnea (OSA) significantly increased the risk of MCI, but only an OSA history predicted progression to Alzheimer's disease (AD) dementia.

CONCLUSION

Our findings suggest that a sleep disorder history usefully aids early detection of cognitive impairment and emphasize that such sleep disorder, particularly OSA, is important as potential target for AD prevention.