Topographical disorientation in community-residing patients with Alzheimer's disease

Background. Based on the hypothesis that declarative memory and navigation ability depend on hippocampal integrity, and the fact that declarative memory declines early in Alzheimer's disease (AD), the authors suggest that topographical disorientation (TD) will be an early manifestation of AD. Subjects and methods. Patients diagnosed With AD based on DSM-IV criteria, residing at home, were studied in a clinic at a 1000-bed referral medical center. Patient characteristics, disease condition, performance on neuropsychological tests, and navigation function were compared between patients with and without current TD. Information regarding the extent and duration of TD and the level of current navigational function were collected during a clinical interview. Results. 112 patients (61 males and 51 females) with mean age of 74 years and disease duration of 37 months completed the study. Among them, 61 currently experienced TD, 20 had required an escort to their home by others, and 28 had TD as an incipient symptom. Those with current TD tended to have a longer disease duration, required an escort to their home by others, and reported a history of repeated change of residence, TD as an incipient symptom, a restricted spatial range within which they felt comfortable (safety range), and disorientation when they were out of familiar territory. In addition, caregivers reported a high level of concern for the safety of those with TD when he or she traveled alone. Conclusion. TD in community-dwelling AD patient is common. Caregivers should pay attention to those with longer disease duration and try to avoid changing residence. Developing a brief and valid test for topographical orientation will be helpful for the early detection of TD.