Factors associated with the Big 5 personality traits in Alzheimer’s disease and related dementias (ADRD)

Abstract

AbstractBackgroundInformant ratings of behavior and personality change are the gold standard of measurement in Alzheimer’s disease and related dementias (ADRD) where insight is often impaired, but informant report can be biased by psychosocial factors such as caregiver burden. This study assessed the impact of caregiver burden on informant ratings of patient Big 5 personality traits (Extraversion, Agreeableness, Conscientiousness, Neuroticism, Openness) and associations between degree of discrepancy between informant and patient ratings with cortical volume in regions implicated in loss of insight.MethodA sample of 70 ADRD participants with heterogeneous neurodegenerative clinical phenotypes (Figure 1) and their informants completed the NEO Personality Inventory (NEO‐PI). Disease severity was measured using the Clinical Dementia Rating Scale (CDR). Caregiver burden was measured using the Zarit Burden Interview (ZBI). Discrepancy scores were computed for all NEO‐PI Big 5 scores and a global discrepancy score. Participants were classified as having high/low discrepancy using a median split for each NEO‐PI discrepancy score. T1‐weighted 3T MRI grey matter volumes were normalized to intracranial volume for all ROIs in the Schaefer100×17 parcellation, and linear regression analyses related global difference score to Bonferroni‐corrected atrophy regions.ResultHigher levels of caregiver burden were associated with higher informant ratings of patient Neuroticism (ß = 0.02, p = .013) and lower informant ratings of patient Agreeableness (ß = ‐0.02, p = .0004), Conscientiousness (ß = ‐0.02, p = .005), and Openness (ß = ‐0.01, p = .014) independent of disease severity. Patients with high global discrepancy scores showed reduced cortical volumes in left ventral PFC, right medial PFC, and right superior temporal gyrus. Patients with low discrepancy scores showed relatively preserved cortical volumes in bilateral somatomotor cortex, right posterior cingulate, and left supplementary motor, superior parietal lobule, and postcentral gyrus (all p‐values<.05, Figure 2). Reduced volumes in the high discrepancy group were driven by patients with bvFTD (Figure 3).ConclusionInformant ratings of Big 5 personality factors may be confounded by caregiver burden, highlighting the need for more objective measures of personality and behavior in ADRD. Additionally, high levels of discrepancy between informant and patient ratings of personality may reflect loss of insight secondary to cortical atrophy in frontal and temporal structures.