Genetic Liability for Schizophrenia May Affect Traumatic Brain Injury Associations
A genetic liability for schizophrenia and other mental disorders appears to factor into the associations between traumatic brain injury and mental disorder and suicide, according to study findings published in JAMA Psychiatry.
“Observational studies have shown that traumatic brain injury is associated with a wide range of mental disorders and suicide,” wrote Søren Dinesen Østergaard, MD, PhD, and coauthors from Aarhus University, Arhus, Denmark. “Whether these associations represent a causal effect is, however, difficult to establish.”
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Suspecting that confounding by genetic liability for mental disorder could play a role in the observed associations, researchers conducted a cohort study that included 40,274 people in Denmark with genotype data linked to hospital diagnoses. The study investigated associations between traumatic brain injury and polygenic risk scores for schizophrenia, bipolar disorder, depression, and attention-deficit/hyperactivity disorder (ADHD).
Among 40,274 people in the analysis, 3341 experienced traumatic brain injury during follow-up: 43.8% were female and 56.2% were male.
Polygenic risk scores for all 4 conditions were positively associated with traumatic brain injury, according to the study. Hazard rate ratios were 1.06 with a polygenic risk score for schizophrenia, 1.04 with a polygenic risk score for bipolar disorder, 1.10 with a polygenic risk score for depression, and 1.12 with a polygenic risk score for ADHD.
“Associations between traumatic brain injury and mental disorder or suicide are likely confounded by genetic liability for mental disorder, which should be factored into future studies of these associations to avoid overestimation of causal effects,” researchers wrote.
