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Longitudinal 18F-Fluorodeoxyglucose Positron Emission Tomography (18F-FDG PET) Findings in Korsakoff Syndrome After Rapid Weight Loss During Tirzepatide Therapy: A Case Report.

Crelier VT, Vidal AS, Rezende NB, et al. Cureus. 2026.
Weak / noneCase reportMentions: Tirzepatide

Editor's note

This single case report describes a 50-year-old man with obesity and chronic alcohol use disorder who developed Korsakoff syndrome during rapid weight loss temporally associated with tirzepatide, a dual GLP-1/GIP receptor agonist. Brain imaging showed hypometabolism in the mammillary bodies progressing to the thalamus and brainstem, and cognitive deficits persisted despite intravenous thiamine. A case report establishes temporal association only, not causation; the patient's alcohol use is itself a major risk factor for thiamine-deficiency brain injury, and rapid caloric restriction from any cause could contribute. The value here is a clinical caution: the authors flag that reduced nutritional intake during incretin-based weight loss may unmask thiamine deficiency in vulnerable people. For tirzepatide readers this is a safety signal warranting nutritional vigilance, not evidence of a common or drug-specific harm.

Plain-language abstract

Doctors describe a single patient, a 50-year-old man with obesity and long-term alcohol use, who developed a serious memory disorder called Korsakoff syndrome during fast weight loss while taking tirzepatide. Brain scans showed reduced activity in memory-related regions, and his memory problems continued even after he received vitamin B1 (thiamine). The authors suggest that eating much less during weight-loss treatment may have triggered a thiamine deficiency in someone already at high risk because of alcohol use. A single case cannot show the drug caused this, since heavy alcohol use is itself a well-known cause of this condition. The take-home point is a caution to check nutrition and consider thiamine in vulnerable patients starting these medicines.