Behavioral and psychological symptoms of dementia in relation to level of cognitive impairment

Background: Many people with dementia exhibit some behavioral or psychological symptoms, e.g.. aggressive or aberrant motor behavior, depression or hallucinations, at some time during the course of the disorder. The aim of the present study was to describe the probability of the occurrence of these symptoms of dementia in relation to the level of cognitive impairment. Methods: 3404 people with cognitive impairment were selected from two large cross-sectional surveys of those in geriatric care settings, conducted in 1982 and 2000 in the county of Vasterbotten, Sweden. Symptoms were assessed using the Multi-Dimensional Dementia Assessment Scale (MDDAS), subsumed with a rotated factor analysis, and investigated in relation to level of cognitive impairment, measured using the Gottfries cognitive scale. Results: The passiveness factor had an almost linear correlation to the level of cognitive impairment (r(2) = 0.237). Non-linear correlations, with highest prevalences in middle-stage cognitive impairment, were found for aggressive behavior (r(2) = 0.057), wandering behavior (r(2) = 0.065), restless behavior (r(2) = 0.143), verbally disruptive/attention-seeking behavior (r(2) = 0.099), regressive/ inappropriate behavior (r(2) = 0.058), hallucinatory symptoms (r(2) = 0.021) and depressive symptoms (r(2) = 0.029). Conclusion: The relations between the behavioral and psychological symptoms of dementia and level of cognitive impairment were non-linear, with higher prevalence rates in the middle stages of dementia, apart from the symptom of passiveness, which increased almost linearly with the severity of cognitive impairment.