The effect of sleep disorders on dementia risk in patients with traumatic brain injury: A large‐scale cohort study

INTRODUCTION: We investigated the association between sleep disorders (SDs) and incident dementia in adults with traumatic brain injury (TBI). METHODS: Adults with a TBI between 2003 and 2013 were followed until incident dementia. Sleep disorders at TBI were predictors in Cox regression models, controlling for other dementia risks. RESULTS: Over 52 months, 4.6% of the 712,708 adults (59% male, median age 44, <1% with SD) developed dementia. An SD was associated with a 26% and a 23% of increased risk of dementia in male and female participants (hazard ratio [HR] 1.26, 95% confidence interval [CI] 1.11–1.42 and HR 1.23, 95% CI 1.09–1.40, respectively). In male participants, SD was associated with a 93% increased risk of early‐onset dementia (HR 1.93, 95% CI 1.29–2.87); this did not hold in female participants (HR 1.38, 95% CI 0.78–2.44). DISCUSSION: In a province‐wide cohort, SDs at TBI were independently associated with incident dementia. Clinical trials testing sex‐specific SD care after TBI for dementia prevention are timely. HIGHLIGHTS: TBI and sleep disorders are linked to each other, and to dementia. It is unclear if sleep disorders pose a sex‐specific dementia risk in brain injury. In this study, presence of a sleep disorder increased dementia risk in both sexes. The risk differed by type of sleep disorder, which differed between the sexes. Sleep disorder awareness and care in persons with brain injury is vital for dementia prevention.