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Traumatic brain injury and young onset dementia: A nationwide cohort study
Author(s) -
Nordström Peter,
Michaëlsson Karl,
Gustafson Yngve,
Nordström Anna
Publication year - 2014
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.24101
Subject(s) - dementia , hazard ratio , traumatic brain injury , medicine , cohort , proportional hazards model , cohort study , confidence interval , poison control , pediatrics , psychiatry , medical emergency , disease
Objective To investigate the association between traumatic brain injuries (TBIs) and the risk of young onset dementia (YOD), that is, dementia before 65 years of age. Methods The study cohort comprised 811,622 Swedish men (mean age = 18 years) conscripted for military service between 1969 and 1986. TBIs, dementia, and covariates were extracted from national registers. Time‐dependent exposures using Cox proportional hazard regression models were evaluated. Results During a median follow‐up period of 33 years, there were 45,249 men with at least 1 TBI in the cohort. After adjustment for covariates, 1 mild TBI (hazard ratio [HR] = 1.0, 95% confidence interval [CI] = 0.5–2.0), at least 2 mild TBIs (HR = 2.5, 95% CI = 0.8–8.1), or 1 severe TBI (HR = 0.7, 95% CI = 0.1–5.2) were not associated with Alzheimer dementia (AD). Other types of dementia were strongly associated with the risk of 1 mild TBI (HR = 3.8, 95% CI = 2.8–5.2), at least 2 mild TBIs (HR = 10.4, 95% CI = 6.3–17.2), and 1 severe TBI (HR = 11.4, 95% CI = 7.4–17.5) in age‐adjusted analysis. However, these associations were largely attenuated after adjustment for covariates (1 mild TBI: HR = 1.7; at least 2 mild TBIs: HR = 1.7; 1 severe TBI: HR = 2.6; p < 0.05 for all). Interpretation In the present study, we found strong associations between YOD of non‐AD forms and TBIs of different severity. These associations were, however, markedly attenuated after multivariate adjustment. Ann Neurol 2014;75:374–381