• Attention and psychomotor (A/P) function [ Time Frame: Measured at diagnostic visit (baseline) and 2 months and 6 months post intervention ] [ Designated as safety issue: No ]
• Learning and memory (L/M) function [ Time Frame: Measured at diagnostic visit (baseline) and 2 months and 6 months post intervention ] [ Designated as safety issue: No ]
• Executive and frontal-lobe (E/F) function [ Time Frame: Measured at diagnostic visit (baseline) and 2 months and 6 months post intervention ] [ Designated as safety issue: No ]
• Sleepiness/Alertness [ Time Frame: Measured at diagnostic visit (baseline) and 2 months and 6 months post intervention ] [ Designated as safety issue: No ]
• Mood [ Time Frame: Measured at diagnostic visit (baseline) and 2 months and 6 months post intervention ] [ Designated as safety issue: No ]
• Quality of Life [ Time Frame: Measured at diagnostic visit (baseline) and 2 months and 6 months post intervention ] [ Designated as safety issue: No ]

• Attention and psychomotor (A/P) function
• Learning and memory (L/M) function
• Executive and frontal-lobe (E/F) function
• Sleepiness/Alertness
• Mood
• Quality of Life (all measured at Month 6)

The purpose of this study is to determine the effectiveness of nasal continuous positive airway pressure (CPAP) therapy for the treatment of obstructive sleep apnea syndrome (OSAS).

BACKGROUND:

Nasal CPAP therapy is in widespread use as the primary treatment for OSAS, a sleep-related breathing disorder affecting more than 15 million Americans. The therapeutic effectiveness of CPAP in providing significant, stable, and long-term neurocognitive or other functional benefits to patients with OSAS has not been systematically investigated.

DESIGN NARRATIVE:

The study is a randomized, blinded, sham-controlled, multi-center trial of CPAP therapy. The principal aims of the study are: 1) to assess the long-term effectiveness of CPAP therapy on neurocognitive function, mood, sleepiness, and quality of life by administering tests of these indices to subjects randomly assigned to active or sham CPAP; 2) to identify specific neurocognitive deficits associated with OSAS in a large, heterogeneous subject population; 3) to determine which deficits in neurocognitive function in OSAS subjects are reversible and most sensitive to the effects of CPAP; 4) to develop a composite multivariate outcome measure from the results of this study that can be used to assess the clinical effectiveness of CPAP in improving neurocognitive function, mood, sleepiness, and quality of life; and 5) to use functional magnetic resonance imaging to compare cortical activation before and after CPAP therapy, and to assess whether this change is associated with improvement in specific neurocognitive task performance. The primary endpoint of the study is the effect of six months of CPAP treatment on neurocognitive function. A total of 1100 subjects (550 per treatment group) will be enrolled from the patient populations at five sites (Stanford University; University of Arizona; Brigham and Women's Hospital; Massachusetts; St. Luke's Hospital, Missouri; St. Mary Medical Center, Washington).

• Lung Diseases
• Sleep Apnea Syndromes
• Sleep

• Device: Positive Pressure Respiration
• Device: Sham CPAP machine

• Active Comparator: Active CPAP
• Placebo Comparator: Sham CPAP

Inclusion Criteria:

• Male or female adults age 18 years or older with a diagnosis of OSAS using clinical criteria defined by the study protocol
• Study participation may require seven or more laboratory visits over six months

Exclusion Criteria:

• Prior treatment for OSAS with continuous positive airway pressure or surgery
• Potential sleep apnea complications that may affect the health or safety of the participant, including low blood oxygen, recent near-miss or prior automobile accident due to sleepiness, congestive heart failure, history of angina, coronary artery disease, myocardial infarction or stroke, cardiac rhythm disturbance, and chronic neurological disorders affecting neurocognitive abilities or daily function
• The use of hypnotics, anxiolytics, sedating antidepressants, anticonvulsants, sedating antihistamines, stimulants or other medications likely to affect neurocognitive function and/or alertness
• Respiratory disease requiring medications (unless on stable medications for 2 months)
• Cancer, unless in remission for greater than one year and not taking exclusionary medications
• Self-reported renal failure
• Pregnancy anytime during a subject's participation
• Psychiatric illness, as defined by a DSM-IV diagnosis, except for depression or mild anxiety
• Narcolepsy, idiopathic hypersomnolence, DSM-IV chronic insomnia, restless legs syndrome, or rapid eye movement (REM) behavior disorder
• Current use of diurnal or nocturnal supplemental oxygen
• Significant vision, hearing, or coordination problems
• Difficulty understanding or speaking English
• Currently working night or rotating shifts
• Consumption of more than 10 caffeinated beverages per day (approximately 1,000 mg per day)
• Smokers whose habit interferes with the overnight polysomnogram or with the battery of testing during the day
• Consumption of more than 2 alcoholic beverages per day
• Any illicit drug usage or marijuana usage more than once a week
• Any individual in the household currently on CPAP or on CPAP in the past
• A score of 26 or less on the Mini Mental State Examination (MMSE)