Rest-Activity Pattern and Circadian Phase Alterations Across the Alzheimer's Disease Clinical Spectrum

Abstract

Actigraphy-derived locomotor activity recordings are novel and critical tools for evaluating rest-activity pattern and circadian phase in humans. We conducted a narrative review assessing rest-activity pattern and circadian phase alterations within various stages of Alzheimer's disease, in consideration of the reciprocal associations between neurodegeneration and circadian rhythm disruption in patients with Alzheimer's disease. The goal of this review was to characterize possible associations between circadian rhythm disruption and neurodegeneration in Alzheimer's disease. To the best of our knowledge, only two studies have assessed rest-activity pattern and circadian phase alterations in the preclinical Alzheimer's disease stage and the results of the studies were inconsistent. Several studies have evaluated rest-activity pattern and circadian phase alterations in patients with Alzheimer's dementia. The most replicated findings were delayed phase and increased activity fragmentation, represented as increased intra-daily variability. Unfortunately, many studies performed in dementia patients have not examined neuroimaging biomarkers or structured neuropsychological tests, thus limiting the specification of dementia clinical diagnoses. Future studies should consider a more comprehensive evaluation of various clinical and biomarker characteristics in patients with dementia or Alzheimer's disease.