The Normalization of Brain (18)F-fluorodeoxy-D-glucose Positron Emission Tomography Hypometabolism following Electroconvulsive Therapy in a 55-year-old Woman with Treatment-resistant Late Onset Depression: A Case Report

Major depressive disorder, especially in later life, has heterogeneous clinical characteristics and treatment responses. Symptomatically, psychomotor retardation, lack of energy, and apathy tends to be more common in people with late-onset depression (LOD). Despite recent advances in psychopharmacologic treatments, 20% to 30% of patients with mood disorders experience inadequate responses to medication, often resulting in a trial of electroconvulsive therapy (ECT). However, the therapeutic mechanism of ECT is still unclear. By using (18)F-fluorodeoxy-D-glucose positron emission tomography-computed tomography ((18)F-FDG PET/CT), we can obtain the status of brain metabolism in patients with neuropsychiatric disorders and changes during psychiatric treatment course. The object of this case report is evaluating the effect of ECT on brain metabolism in treatment-refractory LOD by PET/CT and understanding the mode of action of ECT. In this case report, we presented a 55-year-old female patient who suffered psychotic depression that was resistant to pharmacological treatment. Several antidepressants and atypical anti-psychotics were applied but there was no improvement in her symptoms. The patient presented not only depressed mood and behaviors but also deficit in cognitive functions. We found decreased diffuse cerebral metabolism in her brain (18)F-FDG PET/CT image. ECT resulted in amelioration of the patients’ symptoms and another brain PET imaging 7 weeks after the last ECT course showed that her brain metabolism was normalized.