Alzheimer’s disease is a cognitive impairment, but it can manifest itself in many detrimental ways. These include alterations in daytime activity levels, sleep quality, and awake/sleep patterns. These effects of the disease are often the aspects that are most disturbing to the caregivers4and are therefore reasonable endpoints for testing the efficacy of therapies3. For example, Mahlberg et al. used actigraphy to show a decrease in daytime activity in response to a therapy designed to reduce agitation6.
Activity and sleep can also be markers for cognitive symptoms. Zeitzer et al. showed that patient apathy was highly correlated with a specific daytime activity pattern that was independent of depression7. Carvalho-Bos used actigraphy to show that the instability of the patient’s daily awake/sleep rhythm was related to cognitive decline 2 , and Buchman et al. showed that the level of 5 Galik EM, Resnick B, Gruber-Baldini A, Nahm E, Pearson K, Pretzer- Aboff I. Pilot testing of the restorative care intervention for the activity was associated with the onset of Alzheimer’s disease in a four-year prospective study of 716 older subjects 1 .1 Buchman AS, Boyle PA,Yu L, Shah RC,Wilson RS, Bennett DA. Total daily physical activity and the risk of AD and cognitive decline in older adults. Neurology 2012; 78:1323-1329.