Risk factors for behavioral abnormalities in mild cognitive impairment and mild Alzheimer's disease.

BACKGROUND Behavioral symptoms are common in both mild cognitive impairment (MCI) and Alzheimer's disease (AD). METHODS We analyzed the Neuropsychiatric Inventory Questionnaire data of 3,456 MCI and 2,641 mild AD National Alzheimer's Coordinating Center database participants. Using factor analysis and logistic regression we estimated the effects of age, sex, race, education, Mini-Mental State Examination, functional impairment, marital status and family history on the presence of behavioral symptoms. We also compared the observed prevalence of behavioral symptoms between amnestic and nonamnestic MCI. RESULTS Four factors were identified: affective behaviors (depression, apathy and anxiety); distress/tension behaviors (irritability and agitation); impulse control behaviors (disinhibition, elation and aberrant motor behavior), and psychotic behaviors (delusions and hallucinations). Male gender was significantly associated with all factors. Younger age was associated with a higher prevalence of distress/tension, impulse control and psychotic behaviors. Being married was protective against psychotic behaviors. Lower education was associated with the presence of distress/tension behaviors. Caucasians showed a higher prevalence of affective behaviors. Functional impairment was strongly associated with all behavioral abnormalities. Amnestic MCI patients had more elation and agitation relative to nonamnestic MCI patients. CONCLUSIONS Younger age, male gender and greater functional impairment were associated with higher overall presence of behavioral abnormalities in MCI and mild AD. Marital status, lower education and race had an effect on selected behaviors.