in Community-Dwelling Persons With Alzheimer’s Disease

The behavioral symptoms associated with Alzheimer’s disease (AD) are of intense interest to researchers, clini-cians, and caregivers.1 The relevance of these symptoms has increased with the growing understanding of AD, including the detection of significant psychopathology in persons with mild cognitive impairment (MCI) relative to cognitively intact elderly.2 MCI may be a prodromal stage of AD,3 and the observation of psychopathology in persons with MCI that is similar to the psychopathology of AD sup-ports this argument. The 3 most commonly described types of psychopatho-logical symptoms are agitated, depressive/affective, and psychotic. These symptoms are assessed with a wide vari-ety of instruments,4 but regardless of measurement method, recent investigations have demonstrated that such symp-toms are common and may be interrelated. However, their relationships and their association with the cognitive changes of AD are not yet clearly understood. In the pres-ent report, we explored cross-sectional comorbidity of these symptom types in a cohort of AD patients partici-pating in a clinical trial for treatment of agitation. One factor limiting our understanding of the interre-lationships between these symptom types is the incon-sistency of the literature reporting comorbidity. This could be due, in part, to the heterogeneity of behavioral symp-toms in persons with AD,5 although AD patients exhibit-ing only one symptom type are consistently reported to be relatively rare (eg, Levy et al,6 30%; Frisoni et al,7 12%; Lyketsos et al,8 18%). Between 64%9 and 97%10 of patients have been reported to have one or more behavioral symp-toms at initial evaluation (see also refs 2, 6-8). Symptoms may differ in the degree of persistence over time,9,10 an