Risk of Developing Dementia and Associated Factors in Patients With Normal Brain FDG PET

Brain 18F-FDG PET (positron emission tomography) is recognised as having a good negative predictive value in the search for a neurodegenerative origin of cognitive disorders. Indeed, a ratio of 0.1 on the occurrence of worsening cognitive disorders has been reported in case of normal brain FDG PET. However, the risk of developing objective cognitive disorders in patients with no cognitive complaints is estimated at 8% per year and the risk of developing dementia in patients with mild cognitive disorders at 22% per year. Cerebral 18F-FDG PET is a prognostic factor for the occurrence of unusual clinical manifestations (MCI) or the conversion of MCI to Alzheimer's disease, but we do not really know the impact on the longer term occurrence of cognitive impairment in patients with normal cerebral 18F-FDG PET. Only a longitudinal study will allow us to really know the true negative predictive value of a normal 18F-FDG PET scan and the factors associated with a risk of dementia in these subjects. This will allow us to better understand the prognostic impact of a normal brain 18F-FDG PET scan and to identify a sub-population that remains at risk, including in the case of normal brain 18F-FDG PET.