Apolipoprotein ε4 status is associated with behavioral symptoms in nursing home residents with dementia

Background: While the relationship of apolipoprotein E (APOE) to behavioral symptoms of dementia (BSD) has been studied in community-dwelling persons with AD, it has received limited attention within the nursing home (NH) population. The aim of this study was to examine the association between APOE genotype and BSD in NH residents using direct observation. Methods: Thirty-six participants, aged 71-102 years, were compared using a non-randomized two-group design with continuous measures. APOE genotype was obtained by buccal swab. BSD, including restlessness, escape restraint, tapping and banging, searching and wandering, pacing and walking, and vocalization, were measured using the Modified Agitated Behavior Rating Scale. Participants were observed every 20 minutes for 12 hours per day for five days. Each participant's mean behavior scores were compared according to the presence or absence of the APOE epsilon 4 allele. Results: Resident characteristics included a mean MMSE of 10.44 indicating moderate to severe dementia and a mean of 3.44 medical co-morbidities. Fifty-six percent of the participants had one 0 allele. A significant difference was found between APOE epsilon 4+/4- and mean behavioral scores (F-1,F-31 = 4.40, p = 0.04). Restlessness was significantly inversely correlated with MMSE (r = -0.367, p = 0.03), but not APOE genotype. There was no significant correlation between proxy reporting and direct observation (r = 0.257, p = 0.13). Conclusion: Findings indicate that the presence of the APOE epsilon 4+ genotype increases the risk for BSD in NH residents with dementia. Direct observation proved a more accurate estimate of BSD than proxy report.