Résumé
Personality changes are a clinical criterion for dementia diagnosis, yet their progression across disease stages remains unclear. This systematic review and meta-analyses examined change in the five major personality traits across the preclinical, transitional, and clinical dementia stages. We conducted pre-registered searches of three databases from their inception to November 2024. The standardized mean difference (SMD) with 95 % CIs were combined in random-effects meta-analyses. Prospective studies based on self-reports of personality (13 studies; N = 6895) found subtle changes in the preclinical and transitional stages (SMD = 0-0.2), which became more pronounced (SMD = 0.3-0.5) in the clinical stage. Retrospective studies based on informant ratings (26 studies; N = 1069) found smaller changes during mild cognitive impairment compared to dementia, with large (>1 SMD) increases in neuroticism and decreases in extraversion and conscientiousness. Surprisingly, changes in frontotemporal dementia were slightly smaller than those observed in Alzheimer's disease. By triangulating findings across study designs, we conclude that personality changes are subtle and inconsistent in the early preclinical stage. Personality changes become significant and pronounced as the disease progresses, in line with the rise of emotional and behavioral symptoms. Future multimethod studies should examine to what extent the rate of change is related to the underlying neurodegenerative processes. Our findings provide a framework for interpreting the timing and magnitude of non-cognitive changes in dementia, informing disease monitoring and targeted symptom management.