Depression is common in neurodegenerative diseases, and a psychiatric diagnosis of late-life depression (LLD) may be changed to neurodegenerative disease during the follow-up period. The aim of this study was to identify clinical characteristics of LLD that might be prodromal state of neurodegenerative diseases.

We conducted a retrospective chart review to collect data (registered between April 2012 and September 2022) from individuals who received electroconvulsive therapy (ECT) for their severe depressive episodes due to major depressive disorder (MDD) or bipolar disorder, were aged 60 years and older, and were followed up more than one year. We compared clinical characteristics between individuals whose diagnosis changed from LLD to neurodegenerative disease (ND) and those whose diagnoses didnʼt change (non-ND). Between-group differences were examined using Mann-Whitney U test for continuous variables as well as χ2 tests and Fisherʼs exact tests for categorical variables.

In total, 99 patients (14 patients in ND and 85 patients in non-ND.) were included. All individuals in ND group were diagnosed with MDD. Individuals in ND group showed significantly older onset age, less family history of psychiatric disorders, and tended to show less melancholic features, less ineffective to antidepressants for the current episode. They required ECT because of the need for rapid recovery than non-ND.

Among individuals with late-life mood disorders requiring ECT for their severe depressive episodes which require rapid recovery, higher age of onset and no family history of psychiatric disorder may suggest the presence of neurodegenerative diseases.