Executive functioning in obstructive sleep apnea syndrome patients without comorbidities: Focus on the fractionation of executive functions

Biomarkers of sleep-wake disturbance as predictors of cognitive decline and accelerated disease progression

INTRODUCTION

In older adults, where sleep disturbances and cognitive impairment are common, mounting evidence suggests a potential connection between sleep and cognitive function, highlighting the significance of utilizing sleep as a biomarker for early detection of cognitive impairment to improve clinical outcomes in a noninvasive, cost-effective manner.

AREAS COVERED

This review describes the relationship between sleep and cognitive function in older adults, encompassing both subjective and objective measures of sleep quality, duration, architecture, and sleep-disordered breathing. The authors consider the directionality of the associations observed in prospective and cross-sectional studies, exploring whether sleep disturbances precede cognitive decline or vice versa. Furthermore, they discuss the potential bidirectional relationships between sleep and Alzheimer's disease (AD) risks in older adults while also examining the neurodegenerative pathways of this relationship.

EXPERT OPINION

Routine sleep monitoring in primary care settings has the potential to bolster early detection and treatment of sleep disturbance, and by extension, reduce the risk of dementia. Improving sleep assessment tools, such as wearables, provide scalable alternatives to traditional methods like polysomnography, potentially enabling widespread monitoring of sleep characteristics. Standardized measurement and inclusive participant recruitment are needed to enhance generalizability, while longitudinal studies are essential to understand the interaction between sleep and AD pathology.

Mind reading dysfunctions in patients with obstructive sleep apnoea: A neuropsychological approach

Obstructive sleep apnoea syndrome (OSAS) is a prevalent sleep-related breathing disorder that has been extensively studied for its effects on cognitive functions. However, little attention has been given to investigating Mind Reading (MR) skills in patients with OSAS. In this study, we employed a neuropsychological approach to thoroughly assess various facets of MR skills in patients with OSAS. Forty-two patients with untreated moderate or severe OSAS (AHI ≥15; 30 men, 12 women) and 16 healthy controls (7 men and 9 women), matched by age, were enrolled. To assess MR skills, we used: (i) The Story-based Empathy Task (SET), which includes three experimental conditions: identifying intentions (SET-IA), emotional states (SET-EA), and a control condition for inferring causality reactions (SET-CI); (ii) the Ekman 60 Faces Test (Ek60), which measures emotion recognition from facial expressions. Our findings revealed that patients with OSAS exhibit deficits in emotion-related MR skills, while their ability to make inferences about the cognitive states of social partners remains largely preserved. This finding corroborates previous evidence indicating that social cognition, particularly MR skills, may be one of the cognitive domains affected by OSAS. It emphasizes the significance of investigating social cognition and the relationship between MR skills and social functioning as a new and intriguing area of research in patients with OSAS.

OSA-Onset: An algorithm for predicting the age of OSA onset

STUDY OBJECTIVES

There is currently no way to estimate the period of time a person has had obstructive sleep apnoea (OSA). Such information would allow identification of people who have had an extended exposure period and are therefore at greater risk of other medical disorders; and enable consideration of disease chronicity in the study of OSA pathogenesis/treatment.

METHOD

The 'age of OSA Onset' algorithm was developed in the Wisconsin Sleep Cohort (WSC), in participants who had ≥2 sleep studies and not using continuous positive airway pressure (n = 696). The algorithm was tested in a participant subset from the WSC (n = 154) and the Sleep Heart Health Study (SHHS; n = 705), those with an initial sleep study showing no significant OSA (apnea-hypopnea index (AHI) < 15 events/hr) and later sleep study showing moderate to severe OSA (AHI≥15 events/hr).

RESULTS

Regression analyses were performed to identify variables that predicted change in AHI over time (BMI, sex, and AHI; beta weights and intercept used in the algorithm). In the WSC and SHHS subsamples, the observed years with OSA was 3.6 ± 2.6 and 2.7 ± 0.6 years, the algorithm estimated years with OSA was 10.6 ± 8.2 and 9.0 ± 6.2 years.

CONCLUSIONS

The OSA-Onset algorithm estimated years of exposure to OSA with an accuracy of between 6.6 and 7.8 years (mean absolute error). Future studies are needed to determine whether the years of exposure derived from the OSA-Onset algorithm is related to worse prognosis, poorer cognitive outcomes, and/or poorer response to treatment.

Mentation Tracks Severity but not Oxygenation in Obstructive Sleep Apnea

There is a rough consensus, after decades of research, that obstructive sleep apnea (OSA) is associated with mild cognitive impairments, especially in areas of executive functioning (EF), attention/working memory (A/WM), episodic memory (EM), and speed of speed of information processing (SIP). However, there is less consensus as to whether apnea severity matters for these impairments, which sleep variables matter most to which cognitive domains, whether common OSA comorbidities contribute to these determinations, or whether the apparent associations are really artifacts of these comorbidities. In this study, 40 participants with OSA submitted to polysomnography and to neuropsychological assessment with an expanded Halstead-Reitan Test Battery. Aggregates of tests to cover the four cognitive domains mentioned above were linearly regressed on the apnea-hypopnea index (AHI), the nadir of oxygen saturation (NOS), and hypertension and diabetes mellitus (scored present or absent). The AHI predicted both EF (p = .015; sr2 = .13) and A/WM (p = .023; sr2 = 11) in the primary analyses, and EM (p = .027; sr2 = .10) in the secondary analyses. Thus, AHI may affect EF, A/WM and perhaps EM beyond NOS and beyond two of OSA's most common comorbidities. Implications of these findings are discussed here.

Facial Emotion Recognition Deficit in Children with Moderate/Severe Obstructive Sleep Apnea

Although previous studies have reported a facial expression classification deficit among adults with SDB, we do not know whether these findings can be generalized to children. In our study, children with sleep-disordered breathing (SDB) were divided into three groups: primary snoring (n = 51), mild obstructive sleep apnea (OSA) (n = 39), and moderate/severe OSA (n = 26). All participants, including 20 healthy controls, underwent an overnight polysomnography recording and the Emotional Expression Recognition Task. Psychosocial problems were evaluated using the parent-reported Strengths and Difficulties Questionnaire (SDQ). There was a borderline significant interaction between expression category and group on reaction times. Further analysis revealed that positive classification advantage (PCA) disappeared in the moderate/severe OSA group, whereas it persisted in the control, primary snoring, and mild OSA groups. Emotional symptoms were positively correlated with OAHI. In both the happy and sad conditions, RT was negatively related to age and body mass index (BMI) but was independent of the obstructive apnea-hypopnea index (OAHI), arterial oxygen (SaO₂) and total sleep time. The accuracy of identifying a sad expression was negatively related to conduct problems. Children with moderate/severe OSA exhibited dysfunction in facial expression categorization, which could potentially affect social communication ability.

Neuropsychological and socio-cognitive deficits in patients with obstructive sleep apnea

Introduction: Patients with obstructive sleep apnea (OSA) suffer from several neurocognitive deficits. We investigated the cognitive and socio-cognitive profiles of patients with severe OSA, controlling for potentially relevant mediating variables (i.e. age, body-mass index, cognitive reserve and depression). Moreover, we studied the neuropsychological profile of a high-risk OSA phenotype characterized by severe OSA and severe nocturnal hypoxemia.Method: We assessed 29 previously untreated severe OSA patients with a mean age of 55.6 (± 9.9 years) and a mean apnea-hypopnea index (AHI) of 53.1 (± 17.4). A control group of 34 healthy participants was also enrolled. Participants completed an extensive neuropsychological battery that included social cognition, a relatively new investigation area among OSA patients.Data analysis: Data were analyzed with a Bayesian approach. Specifically, Bayesian ANCOVA was used to investigate whether the grouping variable could predict test performance. Age, body-mass index, cognitive reserve and state of depression were added as covariates to the null model to weight the effects of these potential confounding factors. Three groups were analyzed: healthy controls (H), OSA with severe apnea and severe nocturnal oxygen desaturation (D⁺), and OSA with severe apnea non-desaturators (D^-). Performances on the various neuropsychological tests were treated as the dependent variables.Results: The results indicate that non-verbal reasoning, the theory of mind skills, and mental shifting ability were impaired in OSA patients. Patients with severe nocturnal hypoxemia underperformed compared to patients with the same severity of apnea but non-desaturators. Additionally, we observed a trend toward a worse performance among OSA desaturator patients in the following abilities: constructional ability, short term verbal memory, phonological fluency, and the ability to inhibit automatic and dominant responses.Conclusion: The data suggest a key role of hypoxemia in affecting cognitive functioning in OSA patients. Executive functions and the concomitant involvement of social cognition are particularly affected.

Neurodevelopmental Disorders Commonly Presenting with Sleep Disturbances

There are multiple disorders of neurodevelopment that present with co-occurring sleep disturbances. Many of these neurodevelopmental disorders (NDD) include sleep disturbances in their diagnostic criteria. Neurobiological, genetic, and environmental factors overlap to cause different sleep disorders in individuals with NDD. Caregivers often present reporting either insomnia or hypersomnia, and based on the clinical history and findings from diagnostic tests, an appropriate diagnosis can be made. It is crucial that clinicians understand the different presentations of sleep disturbances in individuals with NDD.

Cognitive profiles in obstructive sleep apnea: a cluster analysis in sleep clinic and community samples

STUDY OBJECTIVES

Although cognitive dysfunction is a recognized consequence of untreated obstructive sleep apnea (OSA), the deficit pattern is heterogeneous. Understanding this heterogeneity may identify those at risk of cognitive deficits and guide intervention strategies. To facilitate understanding, we examined whether distinct profiles of neuropsychological performance were present in OSA and, if so, how they are related to other OSA features.

METHODS

We studied sleep clinic (n = 121) and community (n = 398) samples with moderate-severe OSA (apnea-hypopnea index ≥ 15 events/h). Attention and memory were assessed using the Cognitive Drug Research system. Sleep was assessed using polysomnography in the clinic sample and dual channel (flow, oximetry) portable monitoring in the community sample. Latent profile analysis was used to determine structure of cognitive clusters. Discriminant function analysis was used to examine associations between nocturnal and diurnal features of OSA and profile membership.

RESULTS

Both samples were best characterized by a 3-profile solution: (1) strong thinkers (performed well across most domains and showed greater cognitive reserve); (2) inattentive fast thinkers (strong processing speed but poor ability to maintain attention); and (3) accurate slow thinkers (strengths in maintaining attention but poor processing speed). Profile membership was associated with mean overnight oxygen saturation and cognitive reserve in the clinic sample and the presence of cardiovascular disease and/or diabetes in the community sample.

CONCLUSIONS

These findings help explain the diversity of outcomes in previous studies of cognitive dysfunction in OSA by demonstrating that individual differences in cognitive reserve, nocturnal oxygen saturation, and comorbidities affect how cognition is impacted by OSA.

Performance of facial expression classification tasks in patients with obstructive sleep apnea

STUDY OBJECTIVES

People show a facial recognition speed advantage, termed positive classification advantage (PCA), when judging whether a facial expression is happy compared to angry or sad. This study investigated emotional face recognition by patients with obstructive sleep apnea (OSA) with impaired neurocognition.

METHODS

Thirty-four patients with OSA and 26 healthy control patients who underwent 1 night of polysomnographic evaluation before recruitment were asked to complete an emotion recognition task. Accuracy rates and reaction times were recorded and analyzed using repeated-measures analysis of variance.

RESULTS

When participants were asked to classify positive (happy) versus negative (sad) emotional expressions, the phenomenon of PCA disappeared. Importantly, however, compared with the control patients who showed PCA, patients with OSA identified sad faces faster but were similar in processing happy faces.

CONCLUSIONS

In accordance with previous studies that showed depressive emotion in patients with OSA, our results indicate that patients with OSA show negative bias in facial expression recognition, which might lead to decline in ability of social communication.

[Obstructive sleep apnea syndrome and cognitive impairment]

Sleep-disordered breathing is associated with sleep fragmentation and reduced blood oxygenation due to apnea and hypopnea episodes. Multiple studies indicate that obstructive sleep apnea syndrome (OSAS) can have negative impact on cognitive functioning, primarily executive functions, attention, and episodic memory. The attention is also focused on cognition in patients with neurologic and psychiatric comorbidities. There are different explanatory models, which show the mechanisms of OSAS influence on cognition. However, it is still unclear how the initial severity of the disease and clinical outcomes interrelate, and which factors play role in the compensation of cognitive dysfunction. Better understanding of these issues is crucial for the prevention of cognitive impairment and rehabilitation of cognitive functioning.

Electrophysiological and neuropsychological outcomes of severe obstructive sleep apnea: effects of hypoxemia on cognitive performance

Obstructive sleep apnea syndrome (OSAS) is a sleep disorder characterized with upper airway obstructions. Some studies showed cognitive and electrophysiological changes in patients with OSAS; however, contradictory results were also reported. The purpose of the present study was twofold: (1) to investigate cognitive changes in severe OSAS patients by using neuropsychological tests and electrophysiological methods together, (2) to investigate influence of hypoxemia levels on cognition. Fifty-four severe OSAS patients and 34 age-, gender- and education matched healthy subjects were participated. OSAS patients were further divided into two subgroups according to minimum oxygen saturation levels. All participants underwent a detailed neuropsychological test battery. A classical visual oddball task was used to elicit ERP P300 and mean P300 amplitudes were measured from F_z, C_z and P_z electrode sites. OSAS patients showed reduced mean P300 amplitudes up to 43-51% on all electrode sites compared to healthy controls. Subgroup analysis revealed significant differences in neuropsychological test scores between healthy controls and high hypoxemia OSAS group, as well as between low and high hypoxemia groups. Moreover, both low and high hypoxemia OSAS groups had lower P300 amplitudes compared with healthy controls. P300 amplitudes showed a gradual decline in parallel with increasing hypoxemia severity; however, the difference between high and low hypoxemia OSAS groups did not reach significance. Moderate correlations were found between sleep parameters, neuropsychological test scores and P300 amplitudes. These results suggest that electrophysiological measures could be better indicators of cognitive changes than neuropsychological tests in OSAS, particularly in mildly affected patients.

Relationships between self-reported sleep quality components and cognitive functioning in breast cancer survivors up to 10 years following chemotherapy

OBJECTIVE

Links have been made between aspects of sleep quality and cognitive function in breast cancer survivors (BCS), but findings are heterogeneous. The objective of this study is to examine relationships between specific sleep quality components (latency, duration, efficiency, daytime sleepiness, sleep disturbance, use of sleep aids) and cognitive impairment (performance and perceived), and determine which sleep quality components are the most significant contributors to cognitive impairments in BCS 6 months to 10 years post chemotherapy.

METHODS

Women 21 to 65 years old with a history of non-metastatic breast cancer following chemotherapy completion were recruited. Data collection included surveys to evaluate sleep quality and perceived cognitive impairments, and neuropsychological testing to evaluate verbal fluency and memory. Descriptive statistics, bivariate correlations, and hierarchical multiple regression were calculated.

RESULTS

Ninety women (mean age 49) completed data collection. Moderate significant correlations were found between daytime dysfunction, sleep efficiency, sleep latency, and sleep disturbance and perceived cognitive impairment (Rs = -0.37 to -0.49, Ps < .00049), but not objective cognitive performance of verbal fluency, memory, or attention. After accounting for individual and clinical characteristics, the strongest predictors of perceived cognitive impairments were daytime dysfunction, sleep efficiency, and sleep disturbance.

CONCLUSIONS

Findings support links between sleep quality and perceived cognitive impairments in BCS and suggest specific components of sleep quality (daytime dysfunction, sleep efficiency, and sleep disturbance) are associated with perceived cognitive functioning in this population. Findings can assist clinicians in guiding survivors to manage sleep and cognitive problems and aid in the design of interventional research.

Fractionating Executive Functions of Adults With ADHD

OBJECTIVE

To evaluate the performance of adults with ADHD considering the fractionation of executive functions into six different domains.

METHOD

Participants were adult ADHD patients who were not under the acute effects of medication ( n = 48). Their performance was compared with that of a healthy control group ( n = 20) of comparable age, education, and nonverbal intelligence quotient. The cognitive domains assessed were executive shifting, updating, inhibition of prepotent responses, dual-task performance, planning, and access to long-term memory. We also assessed the symptoms of inattention, hyperactivity/impulsivity, anxiety, and depression by validated questionnaires.

RESULTS

Compared with controls, patients reported more symptoms related to ADHD, anxiety and depression symptoms and were impaired in the shifting cost measure and phonemic fluency (measure of access to long-term memory).

CONCLUSION

ADHD in adults selectively impaired executive shifting and access to long-term memory, domains that may alter performance in a wide range of daily tasks.

Reviewing the relationship between OSA and cognition: Where do we go from here?

Obstructive sleep apnoea (OSA) is a disorder of breathing during sleep resulting in temporary reduction in cerebral oxygenation and sleep disruption. A growing body of research reveals a relatively consistent pattern of deficits in cognition, particularly in attention, episodic memory, and executive function, which are partially remediated by treatment. This is where the consensus ends. Despite a number of competing explanations regarding how OSA affects cognition, reliable evidence is hard to find, which may relate to the many, common conditions co-morbid with OSA or to the methodological challenges in this field. This paper reviews the evidence for cognitive impairment in OSA, the proposed models of cognitive harm, the impact of co-morbidities and the many methodological and theoretical challenges of exploring the effect of OSA on cognition. To overcome some of these challenges, we end by proposing a number of future directions for the field, including suggesting some core design elements for future studies.

Cognitive deficits in obstructive sleep apnea: Insights from a meta-review and comparison with deficits observed in COPD, insomnia, and sleep deprivation

Obstructive sleep apnea (OSA) is a nocturnal breathing disorder that is associated with cognitive impairment. The primary determinants of cognitive deficits in OSA are thought to be sleep disruption and blood gas abnormalities. Cognitive impairment is also seen in other disorders that are characterised primarily by sleep disturbance (e.g., sleep restriction/deprivation, insomnia) or hypoxia/hypercarbia (e.g., chronic obstructive pulmonary disease (COPD)). Assessment of the cognitive deficits observed in these other disorders could help better define the mechanisms underlying cognitive deficits in OSA. This study utilised meta-review methodology to examine the findings from systematic reviews and meta-analyses of the effects of untreated OSA, COPD, insomnia, and sleep deprivation on cognitive function in adults, compared with norms or controls. Eighteen papers met inclusion criteria: seven in OSA, two in insomnia, five in COPD, and four in sleep deprivation. OSA and COPD were both accompanied by deficits in attention, memory, executive function, psychomotor function, and language abilities, suggesting that hypoxia/hypercarbia may be an important determinant of deficits in these domains in OSA. Both OSA and sleep deprivation studies were accompanied by deficits in attention and memory, suggesting that short-term sleep disturbance in OSA may contribute to deficits in these domains. Visuospatial deficits were unique to OSA, suggesting the contribution of a mechanism other than sleep disturbance and hypoxia/hypercarbia to this problem. Our findings suggest that the cognitive deficits associated with untreated OSA are multidimensional, with different physiological disturbances responsible for differing cognitive problems.

Factors affecting executive functions in obstructive sleep apnea syndrome and volumetric changes in the prefrontal cortex

PURPOSE

Obstructive sleep apnea syndrome (OSAS) is associated with cognitive changes and executive functions are among the cognitive domains most affected. However, it is not completely understood which of the factor(s) among hypoxemia, repeated arousal, and sleepiness affect the executive functions. This study aims to evaluate the possible relationship between the executive functions and nocturnal parameters, Epworth Sleepiness Scale (ESS) scores, and prefrontal cortex (PFC) volumes.

PATIENTS AND METHODS

A total of 28 patients aged between 18 and 60 years who were newly diagnosed with OSAS were included in this study. The Wisconsin Card Sorting Test (WCST) and Stroop test which were used in the evaluation of executive functions were applied to all patients. Cranial magnetic resonance imaging (MRI) and volumetric measurements of the PFC were performed. Polysomnography (PSG), WCST, Stroop test, and cranial MRI were also applied to the control group which consisted of age- and education status-matched 15 healthy subjects. The correlation of WCST and Stroop tests and PFC volume, PSG parameters, and ESS scale was examined.

RESULTS

The WCST-6 test scores were statistically significantly higher in the patient group (p = 0.022; p < 0.05). Additionally, the Stroop test 5 (p = 0.043) and Stroop test-5 correction (p = 0.005) measurements were statistically significantly higher in the patient group (p < 0.05). A negative and statistically significant correlation was found between the WCST-4 and WCST-10 and ESS measurements in the patient group (r -0.452; p 0.016; p < 0.05; r -0.437; p 0.020; p < 0.05). However, there was no correlation between the PSG parameters and WCST and Stroop test scores. No statistically significant differences in the MRI volumetric measurements of the PFC were found between the patient and control groups.

CONCLUSIONS

Impairment in the attentive and executive functions in OSAS is evident. The most influential factor is excessive daytime sleepiness, rather than hypoxemia and severity of the disease.

Impact of Obstructive Sleep Apnea on Neurocognitive Function and Impact of Continuous Positive Air Pressure

There is evidence that obstructive sleep apnea (OSA) can negatively impact attention, memory, learning, executive function, and overall intellectual function in adults and children. Imaging techniques, including MRI, MR diffusion tensor imaging, MR spectroscopy, and fMRI, have provided additional insight into the anatomic and functional underpinnings of OSA-related cognitive impairment. Both animal and human studies have looked to elucidate the separate effects of oxygen desaturation and sleep fragmentation on independent aspects of cognition. Data from animal models point to neuro-inflammation and oxidative stress as driving factors of cognitive impairment.

Cognitive deficits in adults with obstructive sleep apnea compared to children and adolescents

Obstructive sleep apnea (OSA) can negatively affect the patient's physical and psychological functioning, as well as their quality of life. A major consequence of OSA is impaired cognitive functioning. Indeed, several studies have shown that OSA mainly leads to deficits in executive functions, attention, and memory. As OSA can present in all age groups, these associated cognitive deficits have been observed in adults, as well as in children and adolescents. However, these cognitive deficits may have a different clinical picture in young patients compared to adults. In this review, we analyze the most affected cognitive domains in adults and children/adolescents with OSA, as evaluated by neuropsychological and neuroimaging studies. We found that deficits in working memory, attention, or executive functions cognitive domains are found in both adults and children with OSA. However, children with OSA also show changes in behavior and phonological processing necessary for proper development. Moreover, we examine the possible OSA treatments in children and adults that can have a positive influence on cognition, and therefore, improve patients' general functioning and quality of life.

Acute personalized habitual caffeine doses improve attention and have selective effects when considering the fractionation of executive functions

Caffeine is widely used, often consumed with food, and improves simple and complex/executive attention under fasting conditions. We investigated whether these cognitive effects are observed when personalized habitual doses of caffeine are ingested by caffeine consumers, whether they are influenced by nutriments and if various executive domains are susceptible to improvement. This was a double-blind, placebo-controlled study including 60 young, healthy, rested males randomly assigned to one of four treatments: placebo fasting, caffeine fasting, placebo meal and caffeine meal. Caffeine doses were individualized for each participant based on their self-reported caffeine consumption at the time of testing (morning). The test battery included measures of simple and sustained attention, executive domains (inhibiting, updating, shifting, dual tasking, planning and accessing long-term memory), control measures of subjective alterations, glucose and insulin levels, skin conductance, heart rate and pupil dilation. Regardless of meal intake, acute habitual doses of caffeine decreased fatigue, and improved simple and sustained attention and executive updating. This executive effect was not secondary to the habitual weekly dose consumed, changes in simple and sustained attention, mood, meal ingestion and increases in cognitive effort. We conclude that the morning caffeine "fix" has positive attentional effects and selectively improved executive updating whether or not caffeine is consumed with food.