COPENHAGEN—Among veterans, a sleep disorder diagnosis is associated with an increased risk of dementia, according to research presented at the 2014 Alzheimer’s Association International Conference. Post-traumatic stress disorder (PTSD) may further increase the risk of dementia among veterans with a sleep disorder.
The results underscore the need to understand the mechanism by which sleep disorders increase the risk of dementia, said Kristine Yaffe, MD, Scola Endowed Chair in Psychiatry and Professor of Psychiatry, Neurology, and Epidemiology at the University of California, San Francisco. The hypoxia associated with sleep-disordered breathing, for example, may increase the amount of amyloid that is deposited in the brain. “If one could prevent dementia … by using continuous positive airway pressure for sleep-disordered breathing or by treating insomnia, this would be a wonderful intervention,” said Dr. Yaffe.
Studies indicate that veterans report insomnia or other sleep quality problems more often than nonveterans do. To analyze whether veterans with sleep problems have an increased risk of developing dementia, Dr. Yaffe and colleagues examined a national data set of health information for veterans. The investigators included 200,000 participants age 55 or older in their analysis. The majority of the veterans were male, and the researchers excluded veterans with dementia. During eight years of follow-up, Dr. Yaffe and colleagues observed which of the veterans developed dementia.
Veterans with a sleep disorder had a 30% higher likelihood of developing dementia than did veterans without a sleep disorder. The increased risk persisted after the investigators adjusted the data for comorbidities such as depression, age, and education. “This is a very robust finding, even after we accounted for other things that might account for one’s poor sleep,” said Dr. Yaffe.
The researchers also analyzed the data for a potential interaction between sleep problems and PTSD. They found that veterans with PTSD and sleep problems had an 80% increased risk of developing dementia. “This [result] made sense to us because we had previously shown that PTSD might increase risk of dementia,” said Dr. Yaffe.
Dr. Yaffe’s research of 2011 indicated that sleep-disordered breathing or sleep apnea approximately doubles the risk of developing dementia and mild cognitive impairment. The sleep problems may increase this risk through the mechanism of hypoxia, according to the researchers.
“Our [current] results further this interesting body of data [suggesting] that sleep problems seem to be a risk factor for developing dementia,” she continued. “We can show that this is true in veterans as well, primarily older male veterans.”