Neuroticism, conscientiousness, and in vivo Alzheimer pathologies measured by amyloid PET and MRI

Aim It has been suggested that personality traits, particularly neuroticism and conscientiousness, are risk factors for Alzheimer's disease (AD) and related cognitive decline. However, the underlying pathological links between personality traits and AD‐related cognitive impairments remain unclear. Thus, the present study investigated associations of neuroticism and conscientiousness with in vivo cerebral amyloid‐beta (Aβ) burden, AD‐signature regional neurodegeneration, and white matter hyperintensities (WMH) in non‐demented middle‐ and old‐aged adults. Methods A total of 397 non‐demented participants underwent comprehensive clinical and neuropsychological assessments, 11C‐labeled Pittsburgh Compound B positron emission tomography, and magnetic resonance imaging. Additionally, the NEO Five‐Factor Inventory was administered to both the participants and their informants to measure neuroticism and conscientiousness. Results Neither neuroticism nor conscientiousness was associated with cerebral Aβ deposition or WMH. In contrast, higher neuroticism and lower conscientiousness, reported by informants in particular, were significantly associated with reduced AD‐signature region cortical thickness. In regards to the direct and indirect effect of each personality on AD‐signature region cortical thickness, only the direct effects were found, whereas indirect effects via Aβ deposition or WMH were not. Conclusion The present findings suggest that amyloid‐independent regional neurodegeneration might underlie relations of neuroticism and conscientiousness with AD.