Agitation is a common problem in institutionalized patients with Alzheimer's disease (AD). 'Sundowning,' or agitation that occurs primarily in the evening, is estimated to occur in 10-25% of nursing home patients. The current study examined circadian patterns of agitation in 85 patients with AD living in nursing homes in the San Diego, California, area. Agitation was assessed using behavioral ratings collected every 15 minutes over 3 days, and activity and light exposure data were collected continuously using Actillume recorders. A five-parameter extension of the traditional cosine function was used to describe the circadian rhythms. The mean acrophase for agitation was 14:38, although there was considerable variability in the agitation rhythms displayed by the patients. Agitation rhythms were more robust than activity rhythms. Surprisingly, only 2 patients (2.4%) were 'sundowners.' In general, patients were exposed to very low levels of illumination, with higher illumination during the night being associated with less robust agitation rhythms with higher rhythm minima (i.e., some agitation present throughout the day and night). Seasonality was examined; however, there were no consistent seasonal patterns found. This is the largest study to date to examine agitation rhythms using behavioral observations over multiple 24h periods. The results suggest that, although sundowning is uncommon, agitation appears to have a strong circadian component in most patients that is related to light exposure, sleep, and medication use. Further research into the understanding of agitation rhythms is needed to examine the potential effects of interventions targeting sleep and circadian rhythms.
Bibliographical noteFunding Information:
This study was supported by NIA AG02711; NIA AG08415; NHLBI HL44915; the Sam and Rose Stein Institute for Research on Aging; the Department of Veterans Affairs VISN-22 Mental Illness Research, Education and Clinical Center (MIRECC); the UCSD Cancer Center; and the Research Service of the Veterans Affairs San Diego Healthcare System. We would like to acknowledge the help of Dr. Jody Corey-Bloom, who conducted the neurological examinations. We would also like to acknowledge the support of the administration, staff, families, and patients at Seacrest Village at Encinitas, the San Diego Hebrew Home at 54th Street, Parkside Special Care Center, Lohar Lodge, and Silverado Senior Living, without whom this study could not have been accomplished.
- Alzheimer's disease
- Circadian rhythms
ASJC Scopus subject areas
- Physiology (medical)