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The relationship between dementia severity and rest/activity circadian rhythms
Phil Gehrman1, Matthew Marler, Jennifer L Martin
1San Diego State University/University of California, San Diego Joint Doctoral Program in Clinical Psychology. sancoliisrael@ucsd.edu
Neuropsychiatric Disease and Treatment
|June 24, 2008
Summary
Rest-activity rhythms in dementia patients show complex changes. Initially, rhythms decline rapidly, then strengthen slightly before declining again in later dementia stages.
Area of Science:
- Gerontology
- Neuroscience
- Sleep Medicine
Background:
- Patients with dementia often exhibit disrupted sleep-wake cycles.
- Impaired endogenous rhythm generation and reduced environmental cue responsiveness are noted in dementia.
Purpose of the Study:
- To investigate the relationship between rest-activity rhythm patterns and dementia severity.
- To explore how rhythm parameters correlate with cognitive decline in nursing home residents with dementia.
Main Methods:
- Actigraphy was used to collect rest-activity data over three days from 150 nursing home patients with dementia.
- Dementia severity was assessed using the Mini-Mental State Examination (MMSE).
- Rhythm parameters were computed and analyzed in relation to MMSE scores.
Main Results:
- Overall, rhythm parameters did not correlate with dementia severity in the entire sample.
- Significant relationships emerged when the sample was stratified by rhythm robustness.
- In less robust rhythm groups, stronger rhythms correlated with less severe dementia.
- In more robust rhythm groups, earlier acrophase and narrower rhythm peaks were linked to milder dementia.
Conclusions:
- A three-stage model for rest-activity rhythm changes in dementia is proposed.
- This model includes rapid initial decline, a subsequent partial recovery, and a further decline in later stages.
- Rhythm disturbances in dementia are dynamic and stage-dependent.
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