Personality and dementia: Personality as risk factor or as early manifestation in dementing disorders?

Less social adaptive personality traits are commonly observed in different forms of dementia, including Alzheimer’s disease, behavioral variant frontotemporal dementia, vascular dementia, and Lewy body diseases. It is likely that these personality traits are a manifestation of the disease, as supported by evidence from “present-time,” retrospective, and clinicopathological studies. The trait neuroticism seems to be an exception and may be a risk factor for the development of dementia. This relationship might be mediated by the influence of neurotic behavior on behavior and lifestyle or by longstanding stress that could lead to atrophy of the medial temporal lobe-a brain structure important for learning and memory. Because many dementing disorders have a long preclinical stage in which brain pathology is present but cognitive function is still unimpaired, future studies on personality as a risk factor for dementia should preferably start at middle age and have a follow-up of at least 20 years. In addition, the relation between personality changes and dementing disorders should be investigated in longitudinal studies using biomarkers for neurodegeneration such as amyloid or tau pathology as an outcome.