Dataset Information

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.

SUBMITTER: Nordstrom A

PROVIDER: S-EPMC5790223 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

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

Nordström Anna A Nordström Peter P

PLoS medicine 20180130 1

<h4>Background</h4>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.<h4>Methods and findings</h4>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 dat ...[more]

PMID: 29381704

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Project description:ObjectiveTo investigate whether sex and race differences exist in dementia diagnosis risk associated with traumatic brain injury (TBI) among older veterans.MethodsUsing Fine-Gray regression models, we investigated incident dementia diagnosis risk with TBI exposure by sex and race.ResultsAfter the exclusion of baseline prevalent dementia, the final sample (all veterans ≥55 years of age diagnosed with TBI during the 2001-2015 study period and a random sample of all veterans receiving Veterans Health Administration care) included nearly 1 million veterans (4.3% female; 81.8% White, 11.5% Black, and 1.25% Hispanic), 96,178 with TBI and 903,462 without TBI. Compared to those without TBI, Hispanic veterans with TBI were almost 2 times more likely (17.0% vs 10.3%; hazard ratio [HR] 1.74, 95% confidence interval [CI] 1.51-2.01), Black veterans with TBI were >2 times more likely (11.2% vs 6.4%; HR 2.15, 95% CI 2.02-2.30), and White veterans with TBI were nearly 3 times more likely to receive a dementia diagnosis (12.0% vs 5.9%; HR 2.71, 95% CI 2.64-2.77). A significant interaction between TBI and race for dementia diagnosis was observed (p < 0.001). Both male and female veterans with TBI were more than twice as likely (men 11.8% vs 5.9%, HR 2.60, 95% CI 2.54-2.66; women 6.3% vs 3.1%, HR 2.36, 95% CI 2.08-2.69) to receive a diagnosis of dementia compared to those without. There was a significant interaction effect between sex and TBI (p = 0.02), but the magnitude of differences was small.ConclusionsIn this large, nationwide cohort of older veterans, all race groups with TBI had increased risk of dementia diagnosis, but there was an interaction effect such that White veterans were at greatest risk for dementia after TBI. Further research is needed to understand the mechanisms for this discrepancy. Differences in dementia diagnosis risk for men and women after TBI were significant but small, and male and female veterans had similarly high risks of dementia diagnosis after TBI.

Project description:IntroductionTraumatic brain injury (TBI) is an occupational health hazard of military service. Few studies have examined differences in military occupational categories (MOC) which take into consideration the physical demands and job requirements across occupational groups.MethodsThis study was approved by the University of Texas Health Science Center at Houston Institutional Review Board. Data for this cross-sectional study were obtained from the Naval Health Research Center's Millennium Cohort Study, an ongoing DoD study. Univariate analyses were employed to calculate frequencies and proportions for all variables. Bivariate analyses included unadjusted odds ratios (OR) and 95% CI for the association between all variables and TBI. Multivariable logistic regression was used to calculate adjusted ORs and 95% CIs to assess the association between MOC and TBI, adjusted for potential confounders: sex, race/ethnicity, rank, military status, branch of service, before-service TBI, and panel. Logistic regression models estimated odds of TBI for each MOC, and stratified models estimated odds separately for enlisted and officer MOCs.ResultsApproximately 27% of all participants reported experiencing a service-related TBI. All MOCs were statistically significantly associated with increased odds of service-related TBI, with a range of 16 to 45%, except for "Health Care" MOCs (OR: 1.01, 95% CI 0.91-1.13). Service members in "Infantry/Tactical Operations" had the highest odds (OR: 1.45, 95% CI 1.31-1.61) of service-related TBI as compared to "Administration & Executives." Among enlisted service members, approximately 28% reported experiencing a service-related TBI. Among enlisted-specific MOCs, the odds of TBI were elevated for those serving in "Infantry, Gun Crews, Seamanship (OR: 1.79, 95% CI 1.58-2.02)," followed by "Electrical/Mechanical Equipment Repairers (OR: 1.23, 95% CI 1.09-1.38)," "Service & Supply Handlers (OR 1.21, 95% CI 1.08-1.37)," "Other Technical & Allied Specialists (OR 1.21, 95% CI 1.02-1.43)," "Health Care Specialists (OR 1.19, 95% CI 1.04-1.36)," and "Communications & Intelligence (OR: 1.16, 95% CI 1.02-1.31)," compared to "Functional Support & Administration." Among officer service members, approximately 24% reported experiencing a service-related TBI. After adjustment the odds of TBI were found to be significant for those serving as "Health Care Officers" (OR: 0.65, 95% CI: 0.52-0.80) and "Intelligence Officers" (OR: 1.27, 95% CI: 1.01-1.61).ConclusionsA strength of this analysis is the breakdown of MOC associations with TBI stratified by enlisted and officer ranks, which has been previously unreported. Given the significantly increased odds of service-related TBI reporting within enlisted ranks, further exploration into the location (deployed versus non-deployed) and mechanism (e.g., blast, training, sports, etc.) for these injuries is needed. Understanding injury patterns within these military occupations is necessary to increase TBI identification, treatment, and foremost, prevention.Results highlight the importance of examining specific occupational categories rather than relying on gross categorizations, which do not account for shared knowledge, skills, and abilities within occupations. The quantification of risk among enlisted MOCs suggests a need for further research into the causes of TBI.

Dataset Information

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

Background

Methods and findings

Conclusions

Publications

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

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