Stereotyped behaviour in elderly patients with chronic organic mental disorder.

The presence of a variety of stereotyped behaviors was verified by observing four residents of a long-term care facility for one-hour each and recording repetitive picking, rubbing, manipulating other parts of the body, vocalizations, manipulation of objects, and sanding. It was found that at least one form of stereotyped behavior was recorded 87% of the total observation time. The overall inter-rater reliability across patients was 91%. Twenty-six patients from another long-term care facility were than randomly chosen, 13 of whom had diagnoses of cortical atrophy, and were observed for an average of 30 seconds each. A trained observer, blind to the diagnoses and to the number of such cases included in the sample, observed stereotyped behavior in and only in the 13 patients with confirmed diagnoses of cerebral dysfunction. A possible mechanism and potential clinical relevance are discussed based upon these observations.