Sleep Disorders Tied to Dementia in Patients With TBI

Patients with traumatic brain injury (TBI) who also had a sleep disorder had an increased risk of developing dementia, a longitudinal analysis showed.

Over more than 4 years, TBI patients with a diagnosed sleep disorder were 25% more likely to develop dementia than TBI patients without a sleep disorder (HR 1.25, 95% CI 1.15-1.36), reported Tatyana Mollayeva, MD, PhD, of Kite Research Institute and the University of Toronto, at SLEEP 2021, a joint meeting of the American Academy of Sleep Medicine and the Sleep Research Society.

Results were similar for each sex. Men with TBI and sleep disorder had an HR of incident dementia of 1.26 (95% CI 1.11-1.42); women had an HR of 1.23 (95% CI 1.09-1.40).

"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," Mollayeva said in a statement. "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 adult patients in Ontario who were dementia-free when they were admitted to the emergency department or acute care hospital with a diagnosis of TBI between May 2003 and April 2013.

All patients were followed to May 2016, until dementia, death, or the end of the study period, whichever happened first. The primary exposure was a sleep disorder, and the primary outcome was dementia. Both were defined by the ICD-10.

The sample included 712,708 patients with TBI of all severities. Median age was 44 and 59% were male.

A total of 6,999 (0.98%) TBI people in the study had a comorbid sleep disorder. Of these, sleep-related breathing disorders (59%) or insomnia disorders (36%) were most common. Sleep disorders were more prevalent in persons who had sustained TBI in falls and in persons with severe TBI.

Over a median follow-up period of 52 months, 32,834 patients (4.6%) developed dementia. Of people who developed dementia, 59% were female. Analyses controlled for age, sex, income level, injury severity, and known comorbidity risks.

When all sleep disorder categories were combined, sleep disorder frequencies were different between the sexes in people with dementia, but similar in those without. Among people without dementia, sleep disorders occurred in 0.97% of women and 0.94% of men with TBI. Among people with dementia, they occurred in 1.3% of women and 2.12% of men.

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

The study had several limitations, Mollayeva noted, it used information about hospital-based services to identify sleep disorders and other risks. It did not distinguish outcomes by sleep disorder. In addition, effects of treatment and treatment adherence were unknown.

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