Blood-Based Biomarkers for Alzheimer's Disease in Older Adults with Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is associated with cognitive decline and risk for dementia, but the neuropathology involved is unclear.

The aim of this study was to determine whether PTSD is associated with increased levels of Alzheimer's disease (AD) blood-based biomarkers.

Individuals aged 50 years and older with PTSD were compared to trauma-exposed healthy controls (TEHCs) at baseline on serum measures of amyloid-β (Aβ) 42 and 40 levels, the Aβ ₄₂/Aβ ₄₀ ratio, and total tau. Serum was analyzed using ultrasensitive Simoa Human Neurology 3-Plex A assay (N3PA). Linear regressions modeling each AD biomarker as a function of group were used to investigate between-group differences, controlling for age, sex, and educational attainment (years).

TEHC participants (N = 26) were 53.8% male with mean age 66.8±10.7, whereas PTSD participants (N = 44) were 47.7% male and aged 62.5±9.1 years. No between-group differences were noted on demographic characteristics or cognitive performance measured with the NIH Toolbox Cognition Battery. There were no significant between-group differences in serum Aβ ₄₀ (TEHC 105.8±51.6 versus PTSD 93.2±56.1, p = 0.46), Aβ ₄₂ (TEHC 8.1±4.6 versus PTSD 7.8±4.6, p = 0.63), Aβ ₄₂/Aβ ₄₀ (TEHC 0.08±0.03 versus PTSD 0.09±0.03, p = 0.27), or total tau (TEHC 0.5±0.3 versus PTSD 0.5±0.4, p = 0.77). Likewise, there were no significant interaction effects of amyloid or tau serum concentrations and PTSD group status on cognitive functioning.

Findings from cognitive assessments and serum analyses do not support PTSD-induced neurodegeneration of the Alzheimer's type as a pathway linking PTSD to increased incidence of dementia in older adults.