Brain FDG PET Scan Flags Cognitive Decline Risk in Psychiatric Patients

Brain fluorodeoxyglucose positron emission tomography, a scanning technique that maps how the brain consumes glucose, may help psychiatrists identify which of their patients with confirmed cognitive symptoms are slipping toward neurodegenerative disease, according to a new study published in EJNMMI Research.

The diagnostic challenge the researchers tackled is a familiar one in clinical practice. Neurodegenerative and psychiatric disorders can produce overlapping symptoms, making it difficult to tell whether memory and thinking problems in a patient with a psychiatric condition reflect the psychiatric illness itself or the early stages of a disease such as Alzheimer’s. The study set out to evaluate the role of brain [18F]FDG PET in a psychiatric population presenting with confirmed cognitive symptoms.

The group had a mean age of 72.9 years and included 21 women. Each patient underwent brain [18F]FDG PET imaging, and the researchers followed them over time to see who developed cognitive deterioration.

During follow-up, eight patients, or 24 percent of the cohort, showed cognitive deterioration. All eight of these patients had an abnormal [18F]FDG PET scan, and five of them displayed a neurodegenerative pattern on imaging. A neurodegenerative pattern, meaning a characteristic redistribution of glucose metabolism seen on the scan, was observed in 11 patients overall, about 32 percent of the study population.

The imaging pattern proved to be a moderately accurate predictor. When the researchers tested whether a neurodegenerative pattern on [18F]FDG PET could predict cognitive deterioration, it achieved an accuracy of 74 percent, with a sensitivity of 63 percent and a specificity of 77 percent. In practical terms, the scan correctly flagged most patients who later declined, while correctly reassuring a majority of those who did not, though neither figure was perfect.

Beyond prediction, the scan appeared to change how psychiatrists thought about their patients. When clinicians were asked about the impact of the PET results on their evaluation, the study found a diagnostic change in 26 percent of patients, and this shift was associated with a statistically significant improvement in the psychiatrist’s diagnostic confidence score, with a p-value below 0.001.

The authors conclude that the findings support the use of brain [18F]FDG PET in the clinical evaluation of patients with psychiatric disorders and confirmed cognitive symptoms, both by identifying patients at risk of cognitive deterioration and by modifying the psychiatrist’s diagnostic assessment.

The study’s scope deserves emphasis. The reported accuracy figures describe how well the imaging pattern performed within this group, not a guarantee of performance in every psychiatric clinic. Because the work was published as an accepted manuscript shared early for faster access, the version is subject to further edits before the final Version of Record appears. Even so, the results suggest that for psychiatrists facing the difficult question of whether a patient’s cognitive symptoms signal something more than the psychiatric condition itself, a metabolic snapshot of the brain may offer clinically meaningful guidance.

Subject of Research: The use of brain FDG PET imaging to predict cognitive deterioration and support diagnosis in psychiatric patients with confirmed cognitive symptoms.

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

Article References: Tahmazov, A., Moulard, M., Kieffer, P., Tahmazov, E., Tarrada, A., Rabearimalala, M., Doyen, M., & Verger, A. (2026). Clinical contribution of brain [18F]FDG PET in psychiatric patients with confirmed cognitive symptoms and suspected neurodegenerative disease. EJNMMI Research. https://doi.org/10.1186/s13550-026-01518-5

Image Credits: AI Generated

DOI: 10.1186/s13550-026-01518-5

Keywords: FDG PET, psychiatry, neurodegenerative disease, cognitive deterioration, depressive disorders, diagnostic confidence, glucose metabolism, EJNMMI Research, dementia risk, brain imaging, Clinical, contribution