BACKGROUND:

The study was a subproject in a Specialized Center of Research in the Cardiopulmonary Disorders of Sleep. Frequent sleep-related respiratory disturbances (SRRD) have been recognized to occur in as many as 70 percent of elderly and 15 percent of middle-aged subjects. Although it is widely agreed that subjects with obvious daytime sleepiness that occurs in association with severe obstructive sleep apnea (Respiratory disturbance indices (RDI) >30) benefit from treatment of their sleep disorders; there is no consensus (and a paucity of data) regarding treatment benefits in subjects with a less profound disorder. Rational utilization of health care resources for diagnosis and treatment of sleep apnea requires assessment of whether adverse health effects occur as a consequence of mild or moderate levels of SRRD, and whether any such health effects may be reversible with treatment.

DESIGN NARRATIVE:

The neuropsychological performance, sleepiness and general functional status were evaluated in 330 subjects, including subjects with little apneic activity (RDI<5), mild activity (RDI 5-14), and moderate activity (RDI 15-25). Of these subjects, 75 percent were selected from a clinic-based sample, and 25 percent were recruited from an ongoing population-based study. 150 subjects with mild and moderate activity were randomized to receive 'conservative' medical therapy (CMT) or CMT plus nasal continuous positive air pressure (CPAP) therapy. Simple statistics, as well as multivariate techniques, were used to determine the relationship between SRRD (and associated hypoxemia, sleep fragmentation, and physiological sleepiness) to: a) intellectual abilities, attention and vigilance, psychomotor performance, learning and memory, and executive functions, and b) to general health status and function. Potential benefits of treatment specific for sleep apnea in subjects with mild and moderate SRRD were also determined after two months of CPAP therapy.