Patients with sleep apnea see cognitive boost after 3 months of continuous positive airway pressure

Patients with obstructive sleep apnea (OSA) may improve their memory by using continuous positive airway pressure (CPAP).

A new study published in the December issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians (ACCP), shows that the majority of patients with OSA, who were memory-impaired prior to treatment, demonstrated normal memory performance after 3 months of optimal CPAP use. The study also showed that memory improvement varied based on CPAP adherence. Patients who used CPAP for at least 6 hours a night were nearly eight times as likely to demonstrate normal memory abilities compared with patients who used CPAP for 2 or fewer hours a night.

 "Patients with OSA often complain of daily forgetfulness, eg, losing their keys, forgetting phone numbers, or forgetting to complete daily tasks," said senior study author Mark S. Aloia, PhD, National Jewish Medical and Research Center in Denver, CO, who conducted his research while at Brown University Medical School, Providence, RI. "Where memory is concerned, we may have the ability to reverse some of the impairments by providing effective and consistent use of CPAP treatment."

Dr. Aloia and colleagues examined the degree to which varying levels of CPAP adherence improved memory in 58 memory-impaired patients with clinically diagnosed OSA. All patients underwent cognitive evaluation involving verbal memory testing prior to initiation of CPAP and at a 3-month follow-up visit. Patients were prescribed CPAP machines, and adherence was covertly monitored using internal microprocessors within each device. After treatment, patients were divided into three groups based on their 3-month CPAP adherence: (1) poor users (n=14), patients who averaged fewer than 2 hours/night of CPAP use; (2) moderate users (n=25), patients who averaged 2 to 6 hours/night of CPAP use; and (3) optimal users (n=19), patients who averaged more than 6 hours/night of CPAP use.

At baseline, all patients were found equally impaired in verbal memory, with the average verbal memory score being approximately 2 SD below the mean for all participants. Following 3 months of CPAP treatment, 21 percent of poor users, 44 percent of moderate users, and 68 percent of optimal users demonstrated normal memory performance. Compared with poor users, optimal users of CPAP were nearly eight times as likely to demonstrate normal memory abilities. Overall, the average verbal memory score for all patients improved approximately 1 SD.

"Moderate use of CPAP may help, but it might not allow patients to reach their full potential recovery where memory is concerned, especially if memory is impaired at baseline," said Dr. Aloia. "For patients with OSA, the more regularly and consistently they use CPAP, the better off they will be." Dr. Aloia believes that getting patients to use CPAP at least 6 hours a night could be a challenge for physicians.

"Our findings also suggest that this optimal level of CPAP adherence is uncommon following 3 months of treatment," said Dr. Aloia. "We need to find ways of encouraging patients to use their treatment all night, every night in order to optimize treatment response."

 "CPAP has proven to be an effective treatment for patients with OSA, yet adherence to treatment remains poor," said Mark J. Rosen, MD, FCCP, President of the American College of Chest Physicians. "Physicians should educate their patients with OSA about the importance of using CPAP consistently and discuss ways to overcome obstacles to adherence."

CHEST is a peer-reviewed journal published by the ACCP. It is available online each month at www.chestjournal.org. The ACCP represents 16,500 members who provide clinical respiratory, sleep, critical care, and cardiothoracic patient care in the United States and throughout the world. The ACCP's mission is to promote the prevention and treatment of diseases of the chest through leadership, education, research, and communication.

www.chestnet.org.