"Sleep, Rhythms and Risk of Alzheimer's Disease: a Daily Life Actigraphic Assessment and MRI Study" "SoRyMA - AMImage3"

Alterations in sleep and the sleep / wake cycle, which are particularly common in Alzheimer's disease patients, could represent an early biomarker for cognitive decline and onset of dementia . Moreover, these disturbances in activity rhythms and sleep patterns represent modifiable factors and therefore potential targets for the prevention of certain neurodegenerative disorders.

The main objective of this study will be to test the hypothesis that elderly people without major cognitive impairment who have circadian rhythm disorders of the sleep / wake cycle have structural and / or functional abnormalities in the central nervous system and more specifically of the hippocampal function which could represent a risk factor for the occurrence of cognitive impairment. Indeed, although many studies in both humans and animals suggest the existence of links between sleep alterations and age-related cognitive impairment, the causality of these observations is still not clear.

This description of the anatomical and functional substratum of sleep / wake cycle alterations occurring in an elderly population will be based on joint analysis of multimodal brain imaging (MRI) and neuropsychology actimetry data. The SoRyMA-AMImage 3 protocol will correspond to the 2nd actimetry measurement point and the 3rd MRI measurement point of a larger population-based cohort AMImage.

This project will collect data from the sleep / wake cycle (actimetry) from a sample of 100 patients included in AMI / AMImage 2 and relate them to brain imaging data (MRI). The main objective of the protocol is the evaluation of the link between changes in sleep and cycle parameters during aging and hippocampal functioning (through fMRI and neuropsychological score of hippocampal dependant tasks). The actimetry variables measured at the two follow-up (4 years apart) will make it possible to measure the degradation of the sleep and cycle parameters (through the reduction of sleep duration, sleep time, increase in sleep fragmentation and decrease in the relative amplitude of the rhythm).

This framework will provide access to a very large amount of data that can be cross-referenced with actimetry data; the longitudinal character of this data collected over a decade will also make it possible to work on the evolution of the actimetry parameters and its relationship with the cognitive and clinical evolution of the subjects. Thus, these data will make it possible to study the prognostic value of the analyzed actimetry parameters in association with very complete clinical and neuropsychological data.