In a study from the VA Boston Healthcare System, scientists found that PTSD, TBI, and the ε4 variant of the APOE gene have strong associations with Alzheimer’s disease and related dementias.
Previous work found a greater percentage of Alzheimer’s and other dementia in Veterans with PTSD and in those with TBI, relative to those without, as well as higher rates of dementia in Veterans who had inherited the ε4 variant.
In the current study, the team used data from VA’s Million Veteran Program (MVP), one of the world’s largest databases of health and genetic information.
They found an increase in risk due to PTSD and TBI in Veterans of European ancestry who inherited the ε4 variant.
In Veterans of African ancestry, the impact of PTSD didn’t vary as a function of ε4, but the TBI effect and interaction with ε4 was even stronger.
Other studies have suggested that ε4 may magnify the effects of a head injury and/or combat-related stress.
These additive interactions indicate that dementia risks associated with PTSD and TBI increased with the number of inherited APOE ε4 alleles.
PTSD and TBI history will be an important part of interpreting the results of dementia genetic testing and doing accurate dementia risk assessment.
The team says the number of ε4 variants a person inherits is fixed at birth, but their impact differs with age.
The risk of Alzheimer’s disease increases with age for all of the APOE genotypes.
But when compared to people with two copies of the common variant, the difference in risk for those with a copy of ε4 appears to peak somewhere between age 65 and 70 and then decrease after that.
Again, that doesn’t mean that your chances of Alzheimer’s decrease after that, just that the difference between the risk for those with and without ε4 diminishes.
If you care about dementia, please read studies about Vitamin B9 deficiency linked to higher dementia risk, and flavonoid-rich foods could help prevent dementia.
For more information about brain health, please see recent studies that cranberries could help boost memory, and these antioxidants could help reduce dementia risk.
The study was conducted by Dr. Mark Logue et al and published in the journal Alzheimer’s & Dementia.
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