Delayed Acrophase May Increase Risk of Dementia
People who experienced a shift in circadian rhythm acrophase had a risk of dementia nearly double that of people whose circadian rhythm remained stable, said Kristine Yaffe, MD, Professor of Psychiatry, Neurology, Epidemiology, and Biostatistics at the University of California, San Francisco. The finding was particularly true for patients whose shift was toward the later part of the day. Circadian rhythms that were not pronounced were also associated with an increased risk of dementia and mild cognitive impairment.
The results stem from Dr. Yaffe’s prospective study of 3,000 community-dwelling women. At enrollment, all participants were age 65 or older. At year 15, Dr. Yaffe and her colleagues assessed patients’ sleep parameters through actigraphy and polysomnography. Five years later, the researchers assessed patients’ cognitive outcomes through a battery of neuropsychologic tests. Patients’ clinical cognitive status was adjudicated.

Women with sleep-disordered breathing at baseline had nearly double the risk of developing dementia or mild cognitive impairment five years later, compared with women without sleep-disordered breathing. “It seems to be the hypoxia that’s related to risk of dementia and mild cognitive impairment, [not] the sleep fragmentation issue,” Dr. Yaffe commented.

This study may help explain why people with advanced dementia have alterations in their sleep–wake cycles, she added. “There may be some links between circadian shifts and amyloid-beta deposition in the brain. It may be possible that we could intervene and then delay, or somehow prevent, some of the cognitive sequelae.”

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Published: June 14, 2012.
Reviewed by Zalman S. Agus, MD; Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

Obstructive sleep apnea patients who use — or even try to use — continuous positive airway pressure (CPAP) devices appear to reduce their overall depressive symptom scores, researchers said here.

In every category measured, patients reduced depressive symptoms, even if they were not using the CPAP devices as prescribed, Charles Bae, MD, of the Cleveland Clinic College of Medicine at Case Western Reserve University told attendees at the annual meeting of the Associated Professional Sleep Societies.

In the key endpoint of decrease of symptoms on the Patient Health Questionnaire, patients who used the devices for 4 hours or more achieved a 3.8-point reduction in scores, compared with a two-point reduction among patients who used the devices less than 4 hours a night (P=0.0009).

“All groups that we measured showed decreases in depressive symptom scores,” Bae told MedPage Today. “We observed reductions in people who used the devices correctly; in patients who didn’t use it correctly or used it less than 4 hours; we observed decreases in these scores if patients had daytime sleepiness; or if they were married or not married.”

He suggested that when people get better sleep, it tends to improve their outlook on other aspects of life.

Bae explained that multiple studies have shown that depressive symptoms are associated with sleep apnea, but there have been conflicting reports as to whether treatment with CPAP improves depressive symptoms. Until his work was performed, no studies had looked at the benefit of CPAP therapy on mood using the Patient Health Questionnaire 9 as a measure of the severity of depressive symptoms.

In his retrospective study, Bae reported on outcomes of 769 patients who filled out the questionnaire between 2008 and 2011. These patients had completed the health questionnaires in the office or at their homes.

The study included individuals 18 years of age or older who had been diagnosed with sleep apnea. They were required to have visited their doctors one time before starting treatment with CPAP and then to have made a second visit at least 30 days later. Patients were not included in the study if they failed to make a follow-up visit.

The average age of the patients in the study was 51.8; 47.3% of the cohort were men; about three-quarters were Caucasian; and 62% were married.

The 654 patients who were adherent in use of CPAP had an average baseline depressive symptom score of 11.2 on the Patient Health Questionnaire 9 and that score dropped 3.8 points, while the 115 non-adherent patients’ scores dropped from baseline of 11.8 to 9.8 – a two-point decrease. The difference in change was statistically significant between the groups (P=0.0009).

“The results were more robust if the patients had expressed sleepiness,” Bae reported. The 475 patients adherent with the therapy who had scored 10 or higher on the Epworth Sleepiness Scale achieved a four-point reduction on the Patient Health Questionnaire 9 compared with a 2.8-point reduction among sleepy subjects who did not adhere to therapy (P=0.0032).

In the 475 married patients, the Patient Health Questionnaire 9 showed a four-point drop after therapy; single individuals had a three-point drop and divorced patients achieved a 2.3-point drop. The difference between divorced and married patients was significant (P=0.0083), Bae said.

“Patients with sleep apnea who are adherent with positive airway pressure therapy – using it more than 4 hours a night — compared to those who are not adherent will have a greater decrease in the Patient Health Questionnaire 9 score,” Bae said.

“These results are not surprising,” said George Thommi, MD, clinical assistant professor of pulmonology at Creighton University School of Medicine, in Omaha, Neb., who was not involved in the study. “I have had several patients myself who have improved depressive symptoms after using positive airway pressure devices.”

He told MedPage Today that the devices help improve sleep. “When you sleep better, you are more likely to feel better and not be as depressed. This work is consistent with what I see in my clinical practice.”