TOPLINE:
METHODOLOGY:
- The study included 597 male decedents who donated their brains to one of two Alzheimer’s Disease Research Center (ADRC) brain bank programs between 1986 and 2018.
- Researchers conducted public data tracing for historical information on military history, which included searching online commercial genealogical databases and paper archives.
- They evaluated tau tangles (using a B score of neurofibrillary tangle deposition in four stages: B0 [not present], B1 [transentorhinal stages], B2 [limbic stages], and B3 [isocortical stages]) and amyloid plaque pathology (using a C score that classifies neuritic amyloid plaque into four categories: no plaques, sparse, moderate, or frequent).
- The study involved three B score comparisons (1, 2, 3 vs. 0; 2, 3 vs. 0, 1; and 3 vs. 0, 1, 2) and two C score comparisons (sparse, moderate, or frequent vs. no plaques, and moderate or frequent vs. no plaque or sparse).
TAKEAWAY:
- Public record tracing determined that 60% of the sample of male decedents had a history of military service; the median year of birth was 1923 and the median year of death was 2007.
- After adjustment for age and year of death, those with a military service history had a 26% increased risk for a higher neuritic amyloid plaque C score compared with those without such history (odds ratio [OR], 1.26; 95% confidence interval [CI], 1.06-1.49), an increase that applied for both relevant comparisons.
- A history of military service was also associated with a 10% greater adjusted odds of a higher neurofibrillary tangle B score (OR, 1.10; 95% CI, 1.08-1.12), with the increase applying to all three comparisons.
- A sensitivity analysis that included both the male decedents and 556 female decedents (increasing the overall sample to 1,153) and was adjusted for sex in addition to age and year of death showed similar results to the male-only sample estimations for both B and C score comparisons.
IN PRACTICE:
Understanding how military service affects AD biological processes is “essential” from a research perspective, the investigators noted. These new findings “emphasize that targeted AD therapies in the veteran population are urgently needed.”
SOURCE:
The study was conducted by W. Ryan Powell, Center for Health Disparities Research and Department of Medicine, Geriatrics Division, University of Wisconsin School of Medicine and Public Health, and colleagues. It was published online in Alzheimer’s & Dementia.
LIMITATIONS:
Selection bias in brain donation is likely because ADRC cohorts are recruitment based. The study was unable to rigorously identify factors that may explain why individuals with military service are at greater risk of having amyloid and tau neuropathology (including the interplay between environmental and genetic risk factors such as apolipoprotein E status).
DISCLOSURES:
The study was supported by the National Institute on Aging. The authors reported no disclosures.
A version of this article appeared on Medscape.com.