Pearls and Pitfalls of 18F-FDG PET/CT for Suspected Alzheimer’s Disease in Patient with Down Syndrome

Dementia in individuals with Down syndrome (DS) is the leading cause of early-onset cognitive decline occurring before the age of 50.However, establishing an accurate diagnosis remains particularly challenging due to pre-existing intellectual disability, variability in baseline cognitive function, and the limited reliability of standard neuropsychological assessments. 18F-fluorodeoxyglucose positron emission tomography ( 18 F-FDG PET) plays a critical role in identifying underlying neurodegenerative processes and supporting the diagnosis.We present a case of DS with multiple known and unknown pathologies identified on brain 18 F-FDG PET and a confirmed diagnosis of early-onset mild Alzheimer's disease.