Clinical contribution of brain [18F]FDG PET in psychiatric patients with confirmed cognitive symptoms and suspected neurodegenerative disease

Brain fluoro-deoxy-glucose positron emission tomography ([18F]FDG PET) can be used in patients with neurodegenerative and psychiatric disorders, for which differential diagnosis is challenging owing to the overlap of symptoms. The aim of this study is to evaluate the role of brain [18F]FDG PET in a psychiatric population presenting with confirmed cognitive symptoms. Thirty-four patients were included in this study (27 with depressive disorders, 7 with a psychotic episode, 72.9 years old, and 21 women). Eight (24%) patients presented cognitive deterioration during follow-up, all presenting an abnormal [18F]FDG PET scan (from whom 5 with a neurodegenerative pattern). A neurodegenerative pattern with [18F]FDG PET, observed in 11 (32%) patients, had an accuracy of 74% (sensitivity of 63%, specificity of 77%) for predicting cognitive deterioration. The clinical impact of the PET results on psychiatrist’s evaluation revealed a diagnostic change in 26% of the patients associated with an improvement in the diagnostic confidence score ( p < 0.001). This study supports the use of brain [18F]FDG PET in the clinical evaluation of patients with psychiatric disorders and confirmed cognitive symptoms by identifying patients at risk of cognitive deterioration and modifying psychiatrist’s evaluation.