[Personality and risk of dementia].

We review the personality construct and its disorders according to the categorical and dimensional approaches, and the present understanding of dementia and its risk factors. This study shows a relationship between pre-morbid personality and risk of developing dementia. Data with speculative character, and indirect proofs from studies on life style, habits and pathological behaviors are reported. Categorical and dimensional parameters of personality are studied respectively by cluster analysis of the DSM classification, and by two contributive instruments: the Cloninger's temperament and character inventory (TCI) with seven dimensions, and the Costa and McCrae's NEO personality inventory (NEO PI) with five factors. Risk of dementia is higher in patients with the DSM C personality cluster, and, by order of severity, the dependent, avoidant and obsessive types of personality. According to the TCI, these three personality types have a high score on the dimension "harm avoidance", which increases the risk of dementia. With the five factor model investigated by the NEO PI, the risk of dementia is increased by low levels of extraversion, openness, agreeableness and conscienciousness, and high level of neuroticism. Biological correlations are mixed up with these two personality models, which have coherent correlations between their respective dimensions. High levels of neuroticism and harm avoidance are associated with low serotonin activity, deficient neuroplasticity, cortisol abnormalities and greater deleterious impact according to the type of stressing situations. Cortisol levels regulation differs according to the type of personality and cortisol axis dysregulation could play a key part in dementia occurrence. Detecting vulnerable personalities should lead to recommendations for dementia prevention.