Traumatic Brain Injury, Post-Traumatic Stress Disorder (PTSD) Is Closely Associated With Alzheimer’s Disease
The researchers found that the prevalence of ADRD in veterans with PTSD and TBI was greater than in those without, as well as a higher rate of ADRD in veterans who inherited the ε4 variant. Then, using a mathematical model, Logue and his colleagues investigated the relationships between variant ε4, PTSD, and TBI.
Veterans of European ancestry are more susceptible to post-traumatic stress disorder
The study found an increased risk of PTSD and TBI in veterans of European ancestry with variant ε4. The effects of PTSD on veterans of African ancestry were not different as a function of ε4, whereas the TBI effect and interaction with ε4 were significantly larger. According to other research, ε4 may amplify the consequences of head trauma and/or combat-related stress.
“These additional interactions indicate that the incidence of PTSD-associated ADRD and TBI increases with the amount of genetic APOE ε4 allele,” wrote Logue and his colleagues. “History of PTSD and TBI will be an important part of interpreting ADRD genetic test results and performing an accurate ADRD risk assessment.”
Advantages of Veterans Administration’s Million Veterans Program
The researchers conducted the study using data from the Veterans Administration’s Million Veterans Program (MVP), one of the world’s largest databases of genetic information. and health. MVP aims to explore how genes, lifestyle, and military exposure affect health and disease, and it currently has more than 900,000 veterans engaged in its mission to reach 1 million and beyond.
Increased rate of memory loss in veterans
With more than 40% of veterans over the age of 75, the number of veterans at risk of Alzheimer’s and other types of dementia is on the rise. While extensive cohort studies have demonstrated that PTSD and TBI increase the incidence of dementia in veterans, Logue and his colleagues looked at this issue in more depth by looking at these risk factors are associated with the APOE variant 4. Most people do not inherit that mutation, but those who do do so from one (or both) of their parents (two copies).
Research has shown that if you inherit one copy of 4, you have a higher risk of developing Alzheimer’s disease,” he said, “and if you inherit two copies, you have a much higher risk of developing the disease.” .”
According to Logue, also a military veteran and associate professor at Boston University, the number of four variants a person receives is fixed at birth, but their effects vary with age.
“The risk of Alzheimer’s disease increased with age for all APOE genotypes,” he said. “But when compared with people with two copies of the common variant, the difference in risk for those with one copy of 4 seems to peak somewhere between the ages of 65 and 70 and then decline. Again, that doesn’t mean your chance of Alzheimer’s disease decreases afterwards, just that the difference between the risk for people with and without ε4 decreases.”
Increased risk of brain damage
Research shows a higher risk of PTSD and brain damage for ε4 gene carriers. According to their estimates, among 80-year-old veterans of European ancestry who do not have the ε4 variant, the incidence of ADRD in those with PTSD will be 6% higher than in those without. However, for 80-year-old veterans of European ancestry who inherit two 4 copies, the incidence of ADRD with PTSD would be 11% higher than in those without the disease.
Association between post-traumatic stress disorder and traumatic brain injury and dementia
Logue was surprised by the clear evidence on the relationship between PTSD and head injury and dementia risk.
“I have been working in Alzheimer’s genetics for over a decade now and I have seen a clear impact of APOE ε4 on Alzheimer’s risk,” he said. “However, in this cohort, the effects of PTSD and head trauma were just as evident and looked similar to the effects of inheriting ε4 from your father or mother.”
Logue and his colleagues then hope to use the MVP data to investigate other risk variables important to veterans, to learn how they might interact with risk variants. risk of Alzheimer’s disease. They also intend to conduct genome-wide association scans to identify new Alzheimer’s and dementia risk mutations. According to Logue, the most recent large-scale genome-wide association study in Alzheimer’s disease discovered about 80 variants associated with Alzheimer’s risk, although those variants are rare or influential. significantly less than ε4.
MVP data can be used to power this type of study, he said, but PTSD and TBI history will be important in interpreting ADRD genetic test results and performing ADRD risk assessments. exactly.
“We know that genes play a big role in Alzheimer’s risk, but they don’t tell the whole story,” explains Logue. “Right now, there’s no genetic test that can tell you if you definitely have Alzheimer’s. The tests can only give an estimate of your chances of getting Alzheimer’s, which can be high. Our research shows that these estimates would be more accurate if they combined factors other than age and genetics.In Veterans, a history of head trauma and PTSD can also make a big difference in dementia risk, so using that information will allow for a more accurate measurement of dementia likelihood.”