OBJECTIVE: To examine whether treatment of obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) in patients with Alzheimer's disease (AD) would result in improved cognitive function. DESIGN: Randomized double-blind placebo-controlled trial. Participants were randomized to either therapeutic CPAP for six weeks or placebo CPAP for three weeks followed by therapeutic CPAP for three weeks. SETTING: General clinical research center PARTICIPANTS: 52 men and women with mild-moderate AD and OSA INTERVENTION: Continuous positive airway pressure MEASUREMENTS: A complete neuropsychological test battery was administered before treatment, at three and at six-weeks. RESULTS: A comparison of subjects randomized to 3 weeks of therapeutic versus placebo CPAP suggested no significant improvements in cognition. A comparison of pre- versus post-treatment neuropsychological test scores after 3 weeks of therapeutic CPAP in both groups showed a significant improvement in cognition. The study was underpowered to make definitive statements about improvements within specific cognitive constructs. However, exploratory post-hoc examination of change scores for individual tests suggested improvements in episodic verbal learning and memory and some aspects of executive functioning such as cognitive flexibility, and mental processing speed. CONCLUSIONS: OSA may aggravate cognitive dysfunction in dementia and thus may be a reversible cause of cognitive loss in AD patients. OSA treatment seems to improve some of the cognitive functioning. Clinicians who care for AD patients should consider implementing CPAP treatment when OSA is present.

A good night's sleep is often more elusive as we age, because the prevalence of insomnia in older people is high. Insufficient sleep can have important effects on daytime function by increasing the need to nap, reducing cognitive ability including attention and memory, slowing response time, adversely affecting relationships with friends and family, and contributing to a general sense of being unwell. However, rather than aging per se, circadian rhythm shifts, primary sleep disorders, comorbid medical/psychiatric illnesses, and medication use cause sleep difficulties in older people, which psychosocial factors may also affect. Clinicians should ask elderly patients about satisfaction with sleep. Any sleep complaints warrant careful evaluation of contributing factors and appropriate treatment.

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