Caroline Cassels

April 19, 2016

VANCOUVER — Sleep problems in older adults have been linked to reduced brain volume, new research shows.

A large, cross-sectional imaging study conducted by investigators at Columbia University in New York showed that longer sleep duration and daytime sleepiness were associated with reduced volume in the entorhinal cortex and reduced gray matter volume, respectively.

"According to our study, self-reported daytime sleepiness is associated with changes in gray and cortical matter volume. Furthermore, night-time sleep duration is associated with left entorhinal volume in a large heterogeneous sample of older adults," said lead researcher, Angeliki Tsapanou, MSc.

Dr Angeliki Tsapanou

The findings were presented here at the American Academy of Neurology (AAN) 2016 Annual Meeting.

The study included 501 participants (71% women) older than age 65 years, recruited from the community as part of the Washington Heights Inwood Community Aging Project (WHICAP).

Sleep problems were assessed by using the 12-item Medical Outcomes Study Sleep Scale, which examined sleep disturbance, snoring, sleep with shortness of breath or with headache, sleep adequacy, and sleep somnolence, with a possible score of 0 to 6 and higher scores indicating greater sleep dysfunction.

The investigators also conducted T-weighted MRI to acquire regional brain volumes. Linear regression models were used to examine the association between sleep problems and brain volume, with each of the sleep questions as the dependent variable.

Results showed that reduced left entorhinal volume was associated with longer sleep duration (P = .003). In addition, reduced cortical (P = .011) and gray matter (P = .010) volume were correlated with increased daytime sleepiness.

After excluding participants with dementia (n = 62), the investigators found that the link between daytime sleepiness and cortical and gray matter volume (P = .008 and P = .009, respectively) became stronger.

Tsapanou noted that the implications of these associations, as well as the causality of the observed association, require further exploration.

"Further longitudinal research is needed in order to shed more light onto the underlying mechanisms of the relationship between sleep patterns and brain volume especially by using objective sleep measures," she concluded.

Cause or Consequence?

Commenting on the study for Medscape Medical News, Ricardo Osorio, MD, New York University Langone Medical Center, said that although the findings are not entirely novel, there are some notable aspects of the research.

Dr Ricardo Osorio

First, he said, the large sample size and the study's focus on older participants are unique and make the study an important contribution to the literature. He also noted that while several studies have shown an association between poor sleep quality and smaller brain volumes, these findings have been reported primarily for the frontal lobes of the brain.

The finding that poor sleep was associated with reduced volume in the entorhinal cortex, an area of the brain that has been implicated in Alzheimer's disease, is important and novel, he said.

This suggests, said Dr Osorio, that poor sleep quality may be a risk factor for Alzheimer's disease. He added that the finding of "reduced gray matter may be less relevant in the sense that it is more unspecific and something that may be related to normal aging."

He also pointed out that longer sleep duration and daytime sleepiness may be markers of sleep apnea.

Last year, Dr Osorio and his team published a paper in Neurology showing that sleep problems, including snoring and sleep apnea, may accelerate mild cognitive impairment by up to 10 years.

As reported by Medscape Medical News at that time, the researchers noted the findings suggest treating disordered sleep using continuous positive airway pressure may help delay cognitive decline.

Importantly, Dr. Osorio noted, it's still not clear from this and other studies whether poor sleep is a cause or consequence of brain atrophy.

"It may be that poor sleep is causing the brain changes, but it definitely could be the other way around — the brain damage could be causing these sleep changes," he said.

Myth Busting

Dr. Osorio also noted there is a prevalent myth that poor-quality sleep in older adults is normal. In the absence of comorbid illness, he said, there is no reason older adults should not have 7 hours of high-quality, restorative sleep per night.

Doctors need to screen for sleep problems in older patients and, if a problem is detected, take steps to address it.

"We need to find out what's causing the problem and not automatically treat the sleep problem [with medication]. Sleep problems can be caused by many things — side effects of medication, apnea, depression, and other issues. The key is to find out what's causing the sleep problem and go from there. We really need to break the myth that elderly people have poor sleep."

The authors and Dr Osorio have disclosed no relevant financial relationships.

American Academy of Neurology (AAN) 2016 Annual Meeting. Abstract S13.007. Presented April 17, 2016.

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