Electroconvulsive therapy as a potential therapeutic option in psychiatric‐onset prodromal dementia with Lewy bodies

Letter to Editor, We read with great interest the article by Fukatsu et al., titled “Electroconvulsive therapy (ECT) improves psychotic symptoms in patients with dementia with Lewy bodies (DLB). ” The authors reported the efficacy and safety of ECT in eight DLB patients. All patients refused to take food and medicine because of systematized delusions; however, there was no relapse of psychotic symptoms during the observation period. In this series, the patient with the lowest Mini‐Mental State Examination (MMSE) score of 4 had the most severe brain atrophy, and developed transient respiratory arrest during ECT. The authors concluded that ECT for mild‐to‐moderate DLB is worth considering as a therapeutic option when psychotic symptoms show resistance to pharmaceutical approaches. However, there is limited information regarding the optimal timing for ECT in prodromal DLB state. Herein, we present a patient with psychiatric‐ onset DLB that underwent ECT after a 10‐month drug treatment for psychiatric symptoms, and discuss the role of ECT in the management of psychiatric‐onset DLB in terms of vulnerability of motor function. Written informed consent was obtained from the patient. A 79‐year‐old functionally independent woman who lived alone moved to her sister's house for the purpose of caring for her sister who had dementia. She developed insomnia, anxiety, and somatic symptoms, including chest discomfort and numbness of the limbs. Two months later, she developed depressive mood with agitation and was administered antidepressant drug treatment by a psychiatrist at a local mental health clinic. Three weeks later, she was admitted to a psychiatric hospital with the worsening agitation and suicidal ideation. She showed hypersensitivity to sertraline and duloxetine, which caused tremors and severe agitation. She experienced a delusion of poverty and gradually developed a psychotic state after the administration of duloxetine. Vortioxetine was partially effective; however, her residential symptoms persisted. She was clinically diagnosed with drug therapy‐resistant psychotic depression and was referred to our university hospital for application of ECT. When she was transferred to our hospital, she predominantly exhibited anxiety, hypochondriasis, dysautonomia, and parkinsonism. Her score on the 17‐item Hamilton Depression Rating Scale (HAM‐D) was 21. The patient scored 25 points on the MMSE and 23 points on the Montreal Cognitive Assessment. Visual processing deficits in cube copying suggested DLB rather than depressive disorder. She needed a walking frame because of muscle weakness due to long‐term hospitalization in addition to parkinsonism, and the motor subscore on the Unified Parkinson's Disease Rating Scale (UPDRS) was 56 points. Considering the use of psychotropic drugs, a differential diagnosis of drug‐induced parkinsonism was required. Magnetic resonance imaging of the head revealed diffuse mild atrophy, and imaging of the dopamine transporter revealed a moderate symmetrical deficit. Considering the effectiveness of olanzapine (7.5 mg/day) on the psychotic state based on medicine history, she underwent six ECT sessions with the same medications. Her HAM‐ D score and UPDRS motor scores improved to 14 and 38 points, respectively. Moreover, her UPDRS motor score improved to 31 points after the administration of L‐dopa (50 mg/day). She was diagnosed with psychiatric‐onset DLB. Considering the risk of dopaminergic agents exacerbating the psychotic state, additional treatment with zonisamide (25 mg/day) and reduction of olanzapine dosage was initiated. Utsumi et al. reported the clinical courses of 21 cases with psychiatric‐onset prodromal DLB. Of the 20 patients who received antidepressants drug therapy before DLB diagnosis, efficacy was observed only in 7 (35%) patients. In contrast, all 10 patients who underwent ECT demonstrated efficacy. Takahashi et al. reported that hypersensitivity to psychotropics was observed in 72.8% of 18 patients with late‐onset major depressive disorder who progressed to DLB. These findings suggest that drug therapy‐resistant psychotic conditions might not be uncommon in the prodromal DLB state. In line with the findings of a recent review regarding ECT for Parkinson's disease, ECT improved motor symptoms as well as psychiatric symptoms in our patient. Treatment with psychotropics for 10 months might exacerbate parkinsonism. Moreover, long‐term hospitalization was presumed to cause muscle weakness, resulting in disability in daily activities. The management of clinical symptoms in patients with prodromal DLB requires balancing the therapeutic effects against the risk of adverse outcomes, including hypersensitivity to psychotropics and long‐term hospitalization. Further studies are needed to determine the optimal timing of ECT in patients with psychiatric‐onset DLB.