Sleep apnea and vigilance performance in a community-dwelling older sample

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.

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.

A review of neurocognitive function and obstructive sleep apnea with or without daytime sleepiness

Excessive daytime sleepiness (EDS) and neurocognitive dysfunction are commonly observed in patients with obstructive sleep apnea (OSA), and these daytime functional deficits can be reversed partly or completely with treatment such as continuous positive airway pressure (CPAP). Although daytime sleepiness is a possible etiology for neurocognitive dysfunction in OSA patients, EDS is not universally present in all patients with OSA. The objective of this review is to summarize the relationship between neurocognitive function and EDS in OSA, as well as the difference in cognitive domains, improvement, and application of CPAP therapy between patients with and without EDS. Two authors independently searched PubMED/Medline, The Cochrane Library and Scopus through May 27, 2015. Sixty-five articles were included in this review. The literature demonstrated a wide range of neurocognitive deficits in OSA patients with EDS, but no more extensive and complex cognitive domains (eg, executive function) in patients without EDS. However, the current literature had very few studies with large sample sizes and extended follow-up that evaluated the effect of CPAP for OSA in patients with and without sleepiness. CPAP failed to improve cognitive dysfunction in OSA patients without EDS after short-term therapy. The evidence suggests that daytime sleepiness possibly relates to the domain and extent of cognitive impairments in OSA, and CPAP therapy has little effect on the improvement of cognitive deficits in OSA patients without EDS. We recommend that additional prospective studies be performed to further quantify the relationship between neurocognitive function in OSA patients with and without EDS.

Effects of continuous positive airway pressure on neurocognitive function in obstructive sleep apnea patients: The Apnea Positive Pressure Long-term Efficacy Study (APPLES)

STUDY OBJECTIVE

To determine the neurocognitive effects of continuous positive airway pressure (CPAP) therapy on patients with obstructive sleep apnea (OSA).

DESIGN, SETTING, AND PARTICIPANTS

The Apnea Positive Pressure Long-term Efficacy Study (APPLES) was a 6-month, randomized, double-blind, 2-arm, sham-controlled, multicenter trial conducted at 5 U.S. university, hospital, or private practices. Of 1,516 participants enrolled, 1,105 were randomized, and 1,098 participants diagnosed with OSA contributed to the analysis of the primary outcome measures.

INTERVENTION

Active or sham CPAP MEASUREMENTS: THREE NEUROCOGNITIVE VARIABLES, EACH REPRESENTING A NEUROCOGNITIVE DOMAIN: Pathfinder Number Test-Total Time (attention and psychomotor function [A/P]), Buschke Selective Reminding Test-Sum Recall (learning and memory [L/M]), and Sustained Working Memory Test-Overall Mid-Day Score (executive and frontal-lobe function [E/F])

RESULTS

The primary neurocognitive analyses showed a difference between groups for only the E/F variable at the 2 month CPAP visit, but no difference at the 6 month CPAP visit or for the A/P or L/M variables at either the 2 or 6 month visits. When stratified by measures of OSA severity (AHI or oxygen saturation parameters), the primary E/F variable and one secondary E/F neurocognitive variable revealed transient differences between study arms for those with the most severe OSA. Participants in the active CPAP group had a significantly greater ability to remain awake whether measured subjectively by the Epworth Sleepiness Scale or objectively by the maintenance of wakefulness test.

CONCLUSIONS

CPAP treatment improved both subjectively and objectively measured sleepiness, especially in individuals with severe OSA (AHI > 30). CPAP use resulted in mild, transient improvement in the most sensitive measures of executive and frontal-lobe function for those with severe disease, which suggests the existence of a complex OSA-neurocognitive relationship.

CLINICAL TRIAL INFORMATION

Registered at clinicaltrials.gov. Identifier: NCT00051363.

CITATION

Kushida CA; Nichols DA; Holmes TH; Quan SF; Walsh JK; Gottlieb DJ; Simon RD; Guilleminault C; White DP; Goodwin JL; Schweitzer PK; Leary EB; Hyde PR; Hirshkowitz M; Green S; McEvoy LK; Chan C; Gevins A; Kay GG; Bloch DA; Crabtree T; Demen WC. Effects of continuous positive airway pressure on neurocognitive function in obstructive sleep apnea patients: the Apnea Positive Pressure Long-term Efficacy Study (APPLES). SLEEP 2012;35(12):1593-1602.

Cognitive function and sleep related breathing disorders in a healthy elderly population: the SYNAPSE study

STUDY OBJECTIVES

Sleep related breathing disorders (SRBD) are risk factors for cognitive dysfunction in middle-aged subjects, but this association has not been observed in the elderly. We assess the impact of SRBD on cognitive performance in a large cohort of healthy elderly subjects.

DESIGN

Cross-sectional study examining the association between subjective memory test, neuropsychological battery testing and SRBD in the elderly.

SETTING

Community-based sample in home and research clinical settings.

PARTICIPANTS

827 subjects, 58.5% women, aged 68 y at study entry, participated in the study. All were free of previously diagnosed SRBD, coronary heart disease, and neurological disorders, including stroke and dementia. Clinical interview, neurological assessment, polygraphy, and extensive cognitive testing were conducted for all participants.

INTERVENTION

N/A.

MEASUREMENT AND RESULTS

SRBD (apnea-hypopnea index [AHI] > 15 events/h) was diagnosed in 445 (53%) subjects, 167 (37%) of them with AHI > 30. Minimal daytime sleepiness was found in the group; 9.2% of the population had an Epworth Sleepiness Scale score > 10. No significant association was found between AHI, nocturnal hypoxemia, and cognitive scores. Comparison of mild vs severe cases showed a trend toward lower cognitive scores with AHI > 30, affecting delayed recall and Stroop test.

CONCLUSIONS

The impact of undiagnosed SRBD on cognitive function appeared quite limited in a generally older healthy population, and only slightly affected severe cases. The implication of undiagnosed SRBD on the cognitive impairment in elderly subjects remains hypothetical and needs to be prospectively studied.

Sleep-disordered breathing and psychomotor vigilance in a community-based sample

STUDY OBJECTIVE

Sleep-disordered breathing (SDB) has been associated with impaired psychomotor vigilance performance in patients with sleep apnea patients. A bias toward greater referral of sleep apnea patients with severely impaired performance could explain these findings. Furthermore, no studies on the association between SDB and vigilance performance in a large community-based sample have been reported that encompasses the full spectrum of SDB severity. This study investigated the association between SDB and psychomotor vigilance with cross-sectional data from the Wisconsin Sleep Cohort Study.

SETTING AND PARTICIPANTS

Community-based sample of 265 women and 346 men, mean age of 53.0 +/- 7.9 (age range: 35-74) years was used. Within 6 months of completing an overnight polysomnography protocol for SDB assessment, participants completed a 10-minute psychomotor vigilance task (PVT) during a daytime protocol.

MEASUREMENTS

Sleep-disordered breathing was indicated by the number of apneas and hypopneas; psychomotor vigilance task variables included (1) mean of 1/reaction time (RT), (2) number of lapses, (3) mean reciprocal of fastest 10% RTs, (4) mean reciprocal of slowest 10% RTs, (5) slope of linear regression line across the 10 minutes of the task fit to 1/RTs, and (5) number of false responses.

RESULTS

Multiple regression analysis showed a significant negative association between the logarithmically transformed apnea-hypopnea index (LogAHI) and number of lapses, mean of the slowest 10%, and number of false responses from the psychomotor vigilance task, independent of sex and body mass index in participants aged 65 years and older.

CONCLUSION

SDB in the community population is associated with impaired psychomotor vigilance in older men and women.

Sleep apnea, APOE4 and Alzheimer's disease 20 years and counting?

Alzheimer's disease (AD) is acknowledged to be at least partially genetic, and one of the key genotypic markers for this condition is the APOE4 allele. Links between sleep apnea and AD have long been suspected because of mental impairment seen in some sleep apnea patients and possible evidence suggesting higher rates of sleep apnea in some dementia patients. The recent demonstration of an association between the APOE4 genotype and sleep apnea has rekindled further interest in this topic, particularly because sleep apnea is characterized by multiple genetic vulnerabilities. We review here evidence related to associations between sleep apnea and dementia, the role of APOE4 as a likely marker for cerebrovascular disease, and discuss treatment considerations relevant to sleep apnea as a potentially reversible cause of dementia.

Epidemiology of obstructive sleep apnea: a population health perspective

Population-based epidemiologic studies have uncovered the high prevalence and wide severity spectrum of undiagnosed obstructive sleep apnea, and have consistently found that even mild obstructive sleep apnea is associated with significant morbidity. Evidence from methodologically strong cohort studies indicates that undiagnosed obstructive sleep apnea, with or without symptoms, is independently associated with increased likelihood of hypertension, cardiovascular disease, stroke, daytime sleepiness, motor vehicle accidents, and diminished quality of life. Strategies to decrease the high prevalence and associated morbidity of obstructive sleep apnea are critically needed. The reduction or elimination of risk factors through public health initiatives with clinical support holds promise. Potentially modifiable risk factors considered in this review include overweight and obesity, alcohol, smoking, nasal congestion, and estrogen depletion in menopause. Data suggest that obstructive sleep apnea is associated with all these factors, but at present the only intervention strategy supported with adequate evidence is weight loss. A focus on weight control is especially important given the expanding epidemic of overweight and obesity in the United States. Primary care providers will be central to clinical approaches for addressing the burden and the development of cost-effective case-finding strategies and feasible treatment for mild obstructive sleep apnea warrants high priority.

Cognitive dysfunction in sleep disorders

Fifty-six studies were reviewed that explored cognitive dysfunctions in people with sleep-related breathing disorders (SRBD, 24 studies), insomnia (18 studies), or narcolepsy (14 studies). Individual study outcomes were grouped according to neuropsychological functions. Available evidence was reviewed separately for SRBD, insomnia and narcolepsy. Consistent evidence was found for impaired driving simulation performance in SRBD patients (92.9% of comparisons with control subjects). Other neuropsychological functions with less pronounced impairment included (i) attention span, divided attention and sustained attention for SRBD patients; (ii) attention span, verbal immediate memory and vigilance for insomniac patients, and (iii) sustained attention, vigilance and driving simulation performance for narcoleptic patients. Reduced performance in tasks measuring attention was found to be higher for SRBD and narcoleptic patients (35.9% and 44.2% of all comparisons, respectively) while this rate was lower for insomniac patients (22.8%). Impairment of memory performance in comparison with control subjects was less pronounced for all three groups, with 20.0% for insomnia, 17.1% for SRBD and 15.6% for narcolepsy. In other areas of cognitive functioning, the data did not allow definite conclusions for any of the patient groups.

Recognition and consequences of obstructive sleep apnea hypopnea syndrome

There is a growing recognition of sleep-disordered breathing (SDB) in patient groups and in the general population. This article reviews issues related to recognizing the disorder, including the problems of relying on narrowly defined polysomnographic data for case findings and for assessment of disease severity. The distributions of symptoms and physiologic measurements of SDB in the population and their inter-relationships are reviewed. The epidemiological data that address risk factors and consequences of sleep apnea hypopnea syndrome (SAHS) also are discussed, with recommendations regarding recognition priorities.

A new visual performance test offers new variables for assessing daytime vigilance: short pauses in performance

A new visual performance test, VigiMouse, was evaluated with the aid of 6 volunteering pediatry residents. The results were compared with a visual analogue scale in differentiating four different states: mild sleep deprivation, low blood alcohol level, a combination of both, and the normal state. A normal night shift at a busy pediatric ward was chosen to represent sleep deprivation. A new set of parameters based on short pauses in performance proved to be more sensitive in detecting small changes in performance than parameters based on reaction times.

Recognition and consequences of obstructive sleep apnea hypopnea syndrome

There is a growing recognition of sleep-disordered breathing (SDB) in patient groups and in the general population. This article reviews issues related to recognizing the disorder, including the problems of relying on narrowly defined polysomnographic data for case findings and for assessment of disease severity. The distributions of symptoms and physiologic measurements of SDB in the population and their inter-relationships are reviewed. The epidemiological data that address risk factors and consequences of sleep apnea hypopnea syndrome (SAHS) also are discussed, with recommendations regarding recognition priorities.

Breathing disorders during sleep and cognitive performance in an older community sample: the EVA Study

OBJECTIVES

To determine whether poor cognitive performance was associated with symptoms related to the sleep apnea syndrome, snoring, and breathing stoppage during sleep.

DESIGN

Cross-sectional analysis of data collected at baseline in the EVA Study, a 4-year cohort study.

SETTING

The city of Nantes in western France.

SAMPLE

A total of 1389 persons, aged 60 to 70 years, recruited from the electoral rolls of the city of Nantes.

MEASUREMENTS

Demographic characteristics and data on drug use and tobacco and alcohol consumption were collected using a standardized questionnaire. Weight and height were measured. Individuals completed a previously validated sleep questionnaire about nocturnal sleep characteristics, snoring, breathing stoppage during sleep, and day-time sleepiness. Trained psychologists administered eight neuropsychological tests: The Mini-Mental State Examination, Trail Making Test, Digit Symbol Substitution Test of the WAIS-Revised, Benton Visual Retention Test, Paced Auditory Serial-Addition Task, Auditory Verbal Learning Test, Raven Progressive Matrices, and Word Fluency Test. Depressive symptomatology was assessed by the Center for Epidemiologic Studies-Depression scale.

MAIN RESULTS

In this older sample, 49.5% of subjects reported snoring, and 10.8% reported breathing stoppage during sleep. Both respiratory disorders were associated significantly with male gender and high body mass index. In men, prevalence of snoring was increased significantly in those with alcohol consumption greater than 40 mL per day. Breathing stoppage during sleep was associated with depressive symptoms in women. Logistic regression models adjusted for age, gender, educational level, tobacco status and alcohol consumption, depressive symptomatology, and number of medications found that both snoring and breathing stoppage were associated with low scores (< or = 10th percentile) in tests requiring visual attention skills, the Trail Making Test (OR = 2.14, 95% CI = 1.24-3.69 and OR = 1.88, 95% CI = 1.04-3.39, respectively), and the Digit Symbol Substitution Test (OR = 1.80, 95% CI = 1.09-2.99 and OR = 1.58, 95% CI = .87-2.89, respectively). These relationships were significant only when either snoring or breathing stoppage was associated with daytime sleepiness.

CONCLUSIONS

This cross-sectional analysis suggested that in community-dwelling individuals 60 to 70 years of age, snoring and breathing stoppage during sleep associated with daytime sleepiness were risk factors for low cognitive performance in tests requiring visual attention skills.

Vigilance and automobile accidents in patients with sleep apnea or narcolepsy

Patients with obstructive sleep apnea or narcolepsy report difficulty remaining alert and attentive. To detect impaired vigilance, we designed Steer Clear, a computer program simulating a long and monotonous highway drive that presents 780 obstacles in 30 min. Sixty-two patients with sleep apnea hit a higher percentage of obstacles (4.3 +/- 0.6% [SEM]) than 12 age- and sex-matched subjects without sleep apnea (1.4 +/- 0.3%; p < 0.05) and 10 age- and sex-matched volunteers (1.2 +/- 0.3%; p < 0.05). Ten patients with untreated narcolepsy hit a higher percentage of obstacles while performing on Steer Clear (7.7 +/- 3.2%) than 10 age- and sex-matched subjects without narcolepsy (1.2 +/- 0.3%; p < 0.05). Poor performance on Steer Clear was associated with a higher auto accident rate in the patients with sleep apnea or narcolepsy (p < 0.01). Twenty-one patients who performed normally on Steer Clear had 1 accident in 5 years (0.05 accident/driver/5 yr), and in none of these accidents were they at fault as drivers. Twenty-five patients who performed poorly on Steer Clear had 5 auto accidents in 5 years (0.20 accident/driver/5 yr), and in 20% of these accidents they were at fault as drivers. Twenty-one patients who performed very poorly on Steer Clear had 8 auto accidents in 5 years (0.38 accident/driver/5 yr), and in 38% of these accidents they were at fault as drivers. These 21 patients who performed very poorly on Steer Clear (hitting > 4.5% of obstacles) had a significantly higher auto accident rate than the patients who performed normally (hitting < 1.8%). We conclude: (1) Patients with sleep apnea or narcolepsy performed more poorly on a test of vigilance, Steer Clear, than did control subjects; (2) Impaired vigilance as measured by Steer Clear is associated with a high automobile accident rate in patients with either sleep apnea or narcolepsy.