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Traumatic brain injury and the risk of dementia diagnosis: A nationwide cohort study.

Abstract

BACKGROUND

Traumatic brain injury (TBI) has been associated with dementia. The questions of whether the risk of dementia decreases over time after TBI, whether it is similar for different TBI types, and whether it is influenced by familial aggregation are not well studied.

METHODS AND FINDINGS

The cohort considered for inclusion comprised all individuals in Sweden aged ≥50 years on December 31, 2005 (n = 3,329,360). Diagnoses of dementia and TBI were tracked through nationwide databases from 1964 until December 31, 2012. In a first cohort, individuals diagnosed with TBI (n = 164,334) were matched with up to two controls. A second cohort consisted of subjects diagnosed with dementia during follow-up (n = 136,233) matched with up to two controls. A third cohort consisted of 46,970 full sibling pairs with discordant TBI status. During a mean follow-up period of 15.3 (range, 0-49) years, 21,963 individuals in the first cohort (6.3% with TBI, 3.6% without TBI) were diagnosed with dementia (adjusted odds ratio [OR], 1.81; 95% confidence interval [CI], 1.75-1.86). The association was strongest in the first year after TBI (OR, 3.52; 95% CI, 3.23-3.84), but the risk remained significant >30 years (OR, 1.25; 95% CI, 1.11-1.41). Single mild TBI showed a weaker association with dementia (OR, 1.63; 95% CI, 1.57-1.70) than did more severe TBI (OR, 2.06; 95% CI, 1.95-2.19) and multiple TBIs (OR, 2.81; 95% CI, 2.51-3.15). These results were in general confirmed in the nested case-control cohort. TBI was also associated with an increased risk of dementia diagnosis in sibling pairs with discordant TBI status (OR, 1.89; 95% CI, 1.62-2.21). A main limitation of the present study is the observational design. Thus, no causal inferences can be made based on the associations found.

CONCLUSIONS

The risk of dementia diagnosis decreased over time after TBI, but it was still evident >30 years after the trauma. The association was stronger for more severe TBI and multiple TBIs, and it persisted after adjustment for familial factors.

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  • Authors+Show Affiliations

    ,

    Department of Public Health and Clinical Medicine, Environmental Medicine, Umeå University, Umeå, Sweden. School of Sports Science, UiT The Arctic University of Norway, Tromsø, Norway.

    Department of Community Medicine and Rehabilitation, Geriatric Medicine, Umeå University, Umeå, Sweden.

    Source

    PLoS medicine 15:1 2018 01 pg e1002496

    MeSH

    Aged
    Aged, 80 and over
    Brain Injuries, Traumatic
    Case-Control Studies
    Cohort Studies
    Dementia
    Female
    Humans
    Incidence
    Male
    Middle Aged
    Odds Ratio
    Retrospective Studies
    Risk Factors
    Sweden

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    29381704

    Citation

    Nordström, Anna, and Peter Nordström. "Traumatic Brain Injury and the Risk of Dementia Diagnosis: a Nationwide Cohort Study." PLoS Medicine, vol. 15, no. 1, 2018, pp. e1002496.
    Nordström A, Nordström P. Traumatic brain injury and the risk of dementia diagnosis: A nationwide cohort study. PLoS Med. 2018;15(1):e1002496.
    Nordström, A., & Nordström, P. (2018). Traumatic brain injury and the risk of dementia diagnosis: A nationwide cohort study. PLoS Medicine, 15(1), pp. e1002496. doi:10.1371/journal.pmed.1002496.
    Nordström A, Nordström P. Traumatic Brain Injury and the Risk of Dementia Diagnosis: a Nationwide Cohort Study. PLoS Med. 2018;15(1):e1002496. PubMed PMID: 29381704.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Traumatic brain injury and the risk of dementia diagnosis: A nationwide cohort study. AU - Nordström,Anna, AU - Nordström,Peter, Y1 - 2018/01/30/ PY - 2017/09/25/received PY - 2017/12/19/accepted PY - 2018/1/31/entrez PY - 2018/1/31/pubmed PY - 2018/12/21/medline SP - e1002496 EP - e1002496 JF - PLoS medicine JO - PLoS Med. VL - 15 IS - 1 N2 - BACKGROUND: Traumatic brain injury (TBI) has been associated with dementia. The questions of whether the risk of dementia decreases over time after TBI, whether it is similar for different TBI types, and whether it is influenced by familial aggregation are not well studied. METHODS AND FINDINGS: The cohort considered for inclusion comprised all individuals in Sweden aged ≥50 years on December 31, 2005 (n = 3,329,360). Diagnoses of dementia and TBI were tracked through nationwide databases from 1964 until December 31, 2012. In a first cohort, individuals diagnosed with TBI (n = 164,334) were matched with up to two controls. A second cohort consisted of subjects diagnosed with dementia during follow-up (n = 136,233) matched with up to two controls. A third cohort consisted of 46,970 full sibling pairs with discordant TBI status. During a mean follow-up period of 15.3 (range, 0-49) years, 21,963 individuals in the first cohort (6.3% with TBI, 3.6% without TBI) were diagnosed with dementia (adjusted odds ratio [OR], 1.81; 95% confidence interval [CI], 1.75-1.86). The association was strongest in the first year after TBI (OR, 3.52; 95% CI, 3.23-3.84), but the risk remained significant >30 years (OR, 1.25; 95% CI, 1.11-1.41). Single mild TBI showed a weaker association with dementia (OR, 1.63; 95% CI, 1.57-1.70) than did more severe TBI (OR, 2.06; 95% CI, 1.95-2.19) and multiple TBIs (OR, 2.81; 95% CI, 2.51-3.15). These results were in general confirmed in the nested case-control cohort. TBI was also associated with an increased risk of dementia diagnosis in sibling pairs with discordant TBI status (OR, 1.89; 95% CI, 1.62-2.21). A main limitation of the present study is the observational design. Thus, no causal inferences can be made based on the associations found. CONCLUSIONS: The risk of dementia diagnosis decreased over time after TBI, but it was still evident >30 years after the trauma. The association was stronger for more severe TBI and multiple TBIs, and it persisted after adjustment for familial factors. SN - 1549-1676 UR - https://www.unboundmedicine.com/medline/citation/29381704/Traumatic_brain_injury_and_the_risk_of_dementia_diagnosis:_A_nationwide_cohort_study_ L2 - http://dx.plos.org/10.1371/journal.pmed.1002496 DB - PRIME DP - Unbound Medicine ER -