Relationship of psychosis to aggression, apathy and function in dementia

BACKGROUND: Psychosis has been associated with aggression in dementia, but the nature of this relationship has been unclear. There has been very little research into the relations between apathy and functional status to psychosis in dementia. The purpose of this study is to investigate the relationship between psychosis and aggression, apathy, and functional status in outpatients with dementia. METHODS: The presence of psychosis was assessed by clinical interview and two scales: the Neuropsychiatric Inventory and the Columbia University Scale for Psychopathology in Alzheimer's Disease. The maximum likelihood estimation technique was used to determine the best estimate of the presence of psychosis. Aggression, apathy, and functional status (activities of daily living: ADLs) were measured using structured instruments. RESULTS: Sixty-one subjects were included. The CUSPAD and NPI provided low false positive and negative rates. ANCOVA analyses showed that psychosis was significantly associated with aggression, even when controlling for apathy, depression, and ADLs. Psychosis was related to apathy only when depression was controlled for. Hallucinations were related to impaired basic ADLs, even when depression and apathy were controlled for. CONCLUSIONS: Relationships were found between psychotic symptoms in dementia and aggression as well as apathy and impaired functional status. These relationships suggest pathophysiologic mechanisms and have possible treatment implications.