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Concussions may increase risk for Alzheimer's disease

Mild traumatic brain injury was associated with cortical thinning in brain regions associated with early Alzheimer’s disease among veterans with PTSD.

“The link between [traumatic brain injury (TBI)] and Alzheimer’s disease has been studied for several decades, with two meta-analyses confirming enhanced risk for Alzheimer’s disease following TBI, particularly among males. However, the mechanisms that instantiate risk for Alzheimer’s disease after TBI are unknown,” Jasmeet P. Hayes, PhD, of the National Center for PTSD, VA Boston Healthcare System, and colleagues wrote.

Jasmeet P. Hayes

To assess mild TBI and genetic risk as predictors of reduced cortical thickness in brain regions associated with early Alzheimer’s disease, researchers evaluated 160 Iraq and Afghanistan war veterans aged 19 to 58 years diagnosed with mild TBI and PTSD.

Analysis indicated mild TBI moderated the association between genetic risk for Alzheimer’s disease and cortical thickness, as individuals with mild TBI and high genetic risk exhibited reduced cortical thickness in regions associated with Alzheimer’s disease.

High genetic risk for Alzheimer’s disease was associated with cortical thinning as a function of time since injury among men with mild TBI.

Moderated mediation analysis indicated mild TBI and high genetic risk indirectly affected episodic memory performance through cortical thickness, which suggests cortical thinning in Alzheimer’s disease-vulnerable brain regions is a mechanism for poorer memory performance, according to researchers.

Analyses of apolipoprotein E4 allele, PTSD and genetic risk for schizophrenia and depression indicated specificity of Alzheimer’s disease polygenic risk finding.

“We found that having a concussion was associated with lower cortical thickness in brain regions that are the first to be affected in Alzheimer's disease,” Hayes said in a press release. “Our results suggest that when combined with genetic factors, concussions may be associated with accelerated cortical thickness and memory decline in Alzheimer’s disease relevant areas.” – by Amanda Oldt

Disclosure: Hayes reports no relevant financial disclosures. Please see the study for a full list of relevant financial disclosures.