News Release

Sleep disorders are associated with increased dementia risk in patients with TBI

Effect of sleep disorders on dementia risk is similar in male and female persons with TBI

Peer-Reviewed Publication

American Academy of Sleep Medicine

DARIEN, IL - Preliminary results from a study of more than 700,000 patients with traumatic brain injury (TBI) show that those with a sleep disorder had an increased risk of developing dementia.

Results show that over a median follow-up period of more than four years, TBI patients with a diagnosed sleep disorder were 25% more likely to develop dementia. The results were similar when stratified by sex: Having a sleep disorder was associated with a 25.5% increase in the risk of incident dementia in male persons with TBI and a 23.4% increase in the risk of developing dementia in female persons with TBI.

"Our study's novelty is its confirmation of sleep disorders' association with incident dementia in both male and female patients, independently of other known dementia risks," said lead author and primary investigator Dr. Tatyana Mollayeva, an affiliate scientist at the Kite Research Institute, the research arm of the Toronto Rehabilitation Institute and one of the principal research institutes at the University Health Network. Mollayeva is part of the Acquired Brain Injury & Society team at KITE. She is also an assistant professor at the Dalla Lana School of Public Health. "We are also the first to report on the risks that sleep disorders and other factors pose separately for male and female patients with TBI."

The retrospective study involved a province-wide cohort of all adult patients who were free of dementia when admitted to the emergency department or acute care hospital with a diagnosis of TBI between May 2003 and April 2013. The total sample comprised 712,708 patients with TBI of all severities. Their median age was 44 years, and 59% were male.

Over a median follow-up period of 52 months, 32,834 patients -- or 4.6% -- developed dementia. Analyses controlled for age, sex, income level, injury severity, and known comorbidity risks.

"The strong links to incidence of dementia in both sexes suggest a need for more targeted sleep disorders risk awareness in patients with TBI," said Mollayeva.

The research abstract was published recently in an online supplement of the journal Sleep and will be presented as an oral presentation on June 13 during Virtual SLEEP 2021. SLEEP is the annual meeting of the Associated Professional Sleep Societies, a joint venture of the American Academy of Sleep Medicine and the Sleep Research Society.


The study was supported by a research grant from the Alzheimer's Association. The authors also were supported by the Eunice Kennedy Shriver National Institute of Child Health & Human Development of the National Institutes of Health, the National Institute of Neurological Disorders and Stroke of the National Institutes of Health, the Canadian Institutes of Health Research through the Institute for Gender and Health, and in part, by the Canada Research Chairs Programs.

For a copy of the abstract, "Contribution of Sleep Disorders to Dementia Incidence Following Traumatic Brain Injury: A Decade-Long Retrospective Cohort Study," or to arrange an interview with the study author or an AASM spokesperson, please contact AASM Communications Coordinator Corinne Lederhouse at 630-737-9700, ext. 9366, or

About the American Academy of Sleep Medicine

Established in 1975, the American Academy of Sleep Medicine (AASM) is advancing sleep care and enhancing sleep health to improve lives. The AASM has a combined membership of 11,000 accredited member sleep centers and individual members, including physicians, scientists and other health care professionals (

About the Sleep Research Society

The Sleep Research Society (SRS) is a professional membership society that advances sleep and circadian science. The SRS provides forums for the exchange of information, establishes and maintains standards of reporting and classifies data in the field of sleep research, and collaborates with other organizations to foster scientific investigation on sleep and its disorders. The SRS also publishes the peer-reviewed, scientific journals Sleep and Sleep Advances (

About the Kite Research Institute

KITE is the research arm of the Toronto Rehabilitation Institute and one of the principal research enterprises at the University Health Network (UHN), Canada's largest medical research hospital. KITE is a world leader in the field of the complex rehabilitation research, with scientists and staff dedicated to improving the lives of people living with the effects of disability, illness and aging. At KITE, our mission is to be a trailblazer in research, education, knowledge translation and clinical application. ( For more information, please contact or

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