Previous studies have suggested that neuroticism, which is closely related to vulnerability to stress, increase the risk of Alzheimer’s disease (AD). However, it is still unclear whether this relationship is directly mediated by AD-specific pathology, cerebral beta-amyloid (Aβ) deposition in particular. We aimed to investigate the associations of neuroticism traits with cerebral amyloid burden and regional cortical thickness in cognitively normal middle- and old-aged adults.
Total 139 participants who were cognitively normal middle- and old-aged adults (mean age=68.9±7.8years: range = 55-87) from the Korean Brain Aging Study for Early Diagnosis & Prediction of Alzheimer’s Disease (KBASE), an ongoing prospective cohort study, were included for analysis. All the subjects underwent comprehensive clinical and neuropsychological assessment, 11C-labelled Pittsburgh Compound B (PiB) positron emission tomography (PET) and Magnetic Resonance Imaging, and blood sampling for ApoE genotyping. The NEO-Five Factor Inventory (NEO-FFI) with both self-report (neuroticism-S) and informant-report (neuroticism-I) were administered to participants and their informants to measure the neuroticism personality traits. Current depressive symptoms were measured using the Geriatric Depression Scale (GDS) and vascular risks were assessed as a vascular risk factor (VRF) score. Global cerebral Aβ deposition was defined as mean cortical PiB retention of the cortical regions including the frontal, lateral temporal, lateral parietal and precuneus/posterior cingulate cortices. Mean regional cortical thickness of the bilateral hemispheres based on Desikan-Killany atlas was measured using the FreeSurfer software.
There was no significant correlation between global or regional PiB retention and neuroticism-S and -I level. However, both neuroticism-S and -I were significantly associated with cortical thinning of the inferior parietal region even after controlling the effect of global PiB retention, ApoE4 carrier status, and VRF score as well as age, gender, education, GDS score. In addition, neuroticism-I was negatively correlated with cortical thickness of the posterior cingulate cortex and temporal regions including the inferior temporal and fusiform gyrus.
Our results suggest that neuroticism traits itself may contribute to neuronal injury in the brain regions commonly involved in AD-type dementia, independently of cerebral Aβ deposition as well as vascular risks and current depression state in cognitively normal middle- and old-aged people.
© 2016 Published by Elsevier Inc.