Personality traits are of raising importance in the investigation of the causes of Alzheimer's disease. The examination of possible correlations between personality traits and the presence of dementia is complicated by some methodical problems concerning the objective, reliable, and valid assessment especially of premorbid personality style of demented persons. There is some evidence that a higher level of education can not be considered as protective factors but seems to delay the progression and modify the clinical manifestation of the disease. How other premorbid personality traits influence the course of the disease is still unresolved. A trend towards an uniform personality alteration in the course of the disease seems to exist. Especially when selecting non-pharmacological therapeutical or training strategies or even in the interaction with the patients, it seems to be important to take personality change into consideration.