HealthDay News — Traumatic brain injury (TBI) is associated with persistently increased risk of dementia, according to a study published online in PLOS Medicine.
Anna Nordström, MD, PhD, and Peter Nordström, MD, PhD, both from Umeå University in Sweden, tracked dementia and TBI diagnoses among all 3,329,360 individuals in Sweden aged ≥50 years on Dec. 31, 2005. In the first cohort, 164,334 individuals diagnosed with TBI were matched with up to two controls. A second cohort included 136,233 subjects diagnosed with dementia during follow-up who were matched with up to 2 controls. A third cohort comprised 46,970 pairs of full siblings with discordant TBI status.
The researchers found that 21,963 individuals in the first cohort were diagnosed with dementia during a median follow-up of 15.3 years (6.3% vs 3.6% with vs without TBI; adjusted OR, 1.81). The correlation was strongest in the first year after TBI (OR, 3.52) and persisted at >30 years (OR, 1.25). A weaker association with dementia was seen for single mild TBI vs more severe TBI or multiple TBIs (odds ratios, 1.63 vs 2.06 and 2.81, respectively).
These results were confirmed in the nested case-control cohort. Among sibling pairs with discordant TBI status, TBI correlated with increased risk of dementia diagnosis (OR, 1.89).
“The risk of dementia diagnosis decreased over time after TBI, but it was still evident >30 years after the trauma,” the authors write.
Nordström A, Nordström P. Traumatic brain injury and the risk of dementia diagnosis: a nationwide cohort study. PLoS Med. 2018;15(1):e1002496.