Does mild traumatic brain injury increase risk of dementia?
Background: Most studies of moderate to severe TBI have found an association with increased risk of dementia and earlier onset of Alzheimer’s. There is growing concern that repeated TBIs, even if more mild, can lead to neurodegenerative conditions such as chronic traumatic encephalopathy (CTE). However, the link between mild TBI and dementia risk has not fully been elucidated, especially in the case of mild TBI without loss of consciousness (LOC).
Recent Data: A recent JAMA study evaluated the association between TBI severity, LOC, and dementia diagnosis in 350,000 veterans between 2001-2013. After adjusting for demographics as well as medical and psych comorbidities, veterans with even mild TBI without LOC had more than a 2-fold increase in risk of dementia diagnosis than those with no TBI. The risk increased only slightly if there was LOC (from a hazard ratio of 2.4 to 2.5). Risk was >3-fold for those with moderate-severe TBI.
Take home: TBI of any severity, even without LOC, appears to be associated with long term neurodegenerative consequences. Avoidance of TBI is of the utmost importance, and if TBI occurs, close neurocognitive follow up should occur.
References
Barnes DE, et al. Association of Mild Traumatic Brain Injury With and Without Loss of Consciousness With Dementia in US Military Veterans. JAMA Neurol. Online May 7, 2018.
