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TBI Linked With Increased Schizophrenia Risk
Traumatic brain injury (TBI) increases subsequent schizophrenia risk by 33%, according to study results published in Psychiatry Research.
Prompted by opposing views regarding the impact of TBI on subsequent risk for certain psychiatric disorders, researchers identified 4184 patients with schizophrenia, along with 18,681 patients with manic depression (BP-I), from Swedish National Registers. Patients were matched 1:5 with control subjects for birth year, sex, and birthplace. The study also featured a sibling comparison to address potential confounders from genetics and familial environments.
According to the findings, the adjusted incidence rate ratio (IRR) for schizophrenia risk with any TBI was 1.33 in the nested case-control analysis. In the sibling comparison, the association between TBI and increased schizophrenia risk remained significant.
The more severe the TBI, the higher the schizophrenia risk, researchers reported. IRRs for schizophrenia were 1.31 with mild TBI and 1.47 with moderate and severe TBI in the case-control analysis.
“A dose-response relationship is an important element in establishing a causal relationship, as it yields evidence of potential biological plausibility and gradient,” wrote corresponding author Sarah E. Bergen, PhD, and study coauthors from Karolinska Institutet, Stockholm, Sweden. “It is possible that the stronger effect from more severe TBI compared to mild TBI reflected a larger degree of neurological damage."
Additionally, the study found that TBI experienced after age 14 years had a stronger effect on schizophrenia risk than TBI that occurred at younger ages.
BP-I risk was similarly affected by TBI, analyses showed.
“The associations between TBI and subsequent schizophrenia and BP-I should prompt clinicians to monitor clinical course and potential psychiatric symptoms in people with a history of TBI,” researchers advised, “particularly the vulnerable groups identified in our study.”
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