Relationship Between Memory and Brain Metabolism is Markedly Disordered in non‐Demented Patients Who Have Worsening Sleep Over Time
Anne E. Hogue, Daniel H. Silverman- Psychiatry and Mental health
- Cellular and Molecular Neuroscience
- Geriatrics and Gerontology
- Neurology (clinical)
- Developmental Neuroscience
- Health Policy
- Epidemiology
Abstract
Background
Disturbances in circadian rhythm often emerge during disease progression in patients with dementia. We recently reported that subjects with worsening sleep experienced significantly faster cerebral decline compared to subjects with improved sleep over comparable timeframes. Here we describe relationships between brain metabolism and memory as a function of changing sleep status.
Method
A consecutive series of 2,005 cognitively normal and mildly impaired subjects from more than 50 North American sites participating in the first three phases of the Alzheimer’s Disease Neuroimaging Initiative was studied. Changes in cognition assessed through formal neuropsychological testing, and in regional cerebral metabolism assessed through brain PET using the radiotracer [F‐18]fluorodeoxyglucose (FDG), were examined. Activities in 47 standardized volumes of interest (sVOI’s), as normalized to each subject’s whole brain activity, were longitudinally measured, and significance of changes in memory were evaluated using a Pearson correlational analysis and two‐sided one‐sample t tests.
Result
In this consecutive series of 2005 subjects, 211 were documented to have had a change in insomnia status during their participation: 83 who were documented to have insomnia at baseline that was subsequently alleviated (“improving sleep”), and 128 who were documented to have no insomnia at baseline but developed it during the study period (“worsening sleep”); among them, 62 (29%) underwent FDG‐PET scans during both baseline insomnia and subsequent insomnia‐free status, or both baseline normal sleep and subsequent insomnia status periods. In subjects with improving sleep, baseline metabolism of posterior cingulate cortex, the brain region with metabolism that declines most significantly in the earliest stages of Alzheimer’s disease, was strongly associated with memory domain performance (r = 0.65, p = 0.00003). In marked contrast, this relationship was severely degraded in subjects who had worsening sleep (r = 0.20, p = 0.18). Similar relative relationships, though somewhat less statistically dramatic, were also observed with respect to global cognition, as assessed by both ADAS‐COG and MMSE scores in both groups of subjects.
Conclusion
Subjects with worsening sleep over time showed a highly disordered relationship between their baseline regional brain metabolism and cognitive function, and this effect was most dramatic with respect to their memory domain performance.