Genetics, Comorbidities, and Ethnicity: Effects of TBI on Dementia

Up to 20 percent of young veterans have had a traumatic brain injury (TBI), with many older veterans having TBI as well. Some epidemiological studies have reported a link between TBI and increased risk of dementia even after years of active life postinjury, however, few have examined what factors may increase or decrease the risk of dementia after TBI. In recent decades,as the country has become more racially and ethnically diverse, so has the U.S. military. However, no studies have examined how race and ethnicity may influence the TBI outcomes and risk of developing dementia. Findings have linked TBI with negative socioeconomic, medical and psychiatric consequences. Yet, these factors also have been identified independently as risk factors for cognitive impairment. This new and unique research collaboration will leverage two established epidemiological datasets to investigate factors associated with adverse cognitive outcomes among veterans with head injuries. Our overall hypothesis is that veterans who are non-white, have lower socioeconomic status and education, and those with greater psychiatric and medical comorbidities will have a higher risk of dementia after TBI. Further, we hypothesize that these differences will still be present after accounting for early life exposures and genetics by studying a large cohort of 3000 twin pairs. Finally, we will determine the population attributable risk (PAR) or proportion of dementia attributable to TBI, both among Veterans and non-veterans. This estimate will allow us to compare TBI to other important risk factors in order to design better prevention and intervention strategies and help highlight the public health significance of TBI.