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Title: Activity-rest and neuroendocrine rhythms in ageing and Alzheimer's disease
Author: Hatfield, C. F.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2002
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The activity patterns of twenty seven subjects with AD, eighteen healthy elderly subjects and 16 healthy young subjects, all living at home, were recorded actigraphically for one month. Non-parametric circadian rhythm analysis (NPCRA) was used to describe the activity patterns. Subjects provided timed saliva samples for determination of cortisol and DHEA patterns. The mini mental state examination (MMSE) was used to assess global cognitive function. Elderly subjects had significantly more stable activity patterns than young subjects and a lower amplitude of the activity profile due to declining activity in the latter part of the day. DHEA levels were significantly reduced in older subjects but cortisol levels and patterning were unchanged. Subjects with mild AD had activity patterns similar to those of elderly controls. Subjects with moderate AD had significantly less stable, more fragmented, lower amplitude activity patterns than controls. Greater instability of daily activity-rest patterns was associated with an increasing degree of cognitive impairment. Neuroendrocine secretion patterns were normal even in subjects with impaired activity-rest patterning. Fourteen AD subjects and seventeen elderly control subjects were re-assessed after one year. At the repeat assessment MMSE scores, activity measures and cortisol secretion patterns were stable for control subjects. Both mild and moderate AD subjects showed significant cognitive decline. The moderate AD subjects also had a reduced amplitude for the activity-rest pattern at follow up. Of the ten most impaired subjects assessed in the first year of the study, five had died or been institutionalised at follow up and five were still living at home. These groups were not differentiated by baseline MMSE scores but the five subjects with a poor outcome had significantly worse activity-rest patterning at first assessment. These findings suggest that sleep disturbance is due to dysfunction downstream from the core oscillator rather than impairment of central pacemaker function.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available