Validity and reliability of the dementia behavior disturbance scale.

Behavioral disturbance is a common and distinctive feature of Alzheimer's disease and other dementias. Existing instruments designed to quantify behavior disturbance among patients with dementia tend to be quite heterogeneous, including many items that do not refer to behavioral disturbance as such, but rather to cognitive, psychological, or somatic symptoms, or functional impairments. A 28-item Dementia Behavior Disturbance (DBD) scale was developed to avoid some of the problems encountered with the older instruments. In two samples of patients with dementia (n = 50 and n = 46), the most common symptoms were repetitive questions, losing or hiding things, lack of interest in daily activities, nocturnal wakefulness, unwarranted accusations, excessive daytime sleeping, and pacing. The coefficient of internal consistency was greater than .80 in both samples, and the correlation between scores obtained from the same subjects at a two-week interval was moderately high (Pearson's correlation coefficient = .71). There was a relatively high correlation between DBD scores and scores on Greene's Behavior and Mood Disturbance scale, and higher DBD scores were associated with increased duration and severity of disease. These preliminary results indicate that the DBD may be a useful and valid measure of one dimension of the dementia syndrome.