Characteristics of Severe Late-Life Depression in the Prodromal Phase of Neurodegenerative Dementia

Objective Late-life depression (LLD) is associated with neurodegenerative disease. The clinical characteristics of patients with LLD who develop neurodegenerative dementia or mild cognitive impairment (MCI) have not been thoroughly investigated. There has also been evidence that the severity of depression affects the transition to dementia. However, the clinical characteristics of the most severely depressed patients who receive the electroconvulsive therapy (ECT) and subsequently transition to a diagnosis of neurodegenerative disease remain unclear. Method We conducted a retrospective chart review of patients who received ECT between April 2012 and September 2022 at our academic hospital. We compared the clinical characteristics of individuals who transitioned to a diagnosis of neurodegenerative diseases and those whose diagnoses remained stable over a follow-up period of more than one year. Results Of the 94 patients who underwent ECT, 12 (13%) were diagnosed with neurodegenerative disease 20 months after their last ECT session. These patients had an older age of onset (p = 0.01), fewer melancholic features (p = 0.03), and fewer family histories of psychiatric disorders (p = 0.01) than those whose diagnoses did not change. Conclusions It is clinically important to consider the potential transition of older individuals with severe depression to neurodegenerative dementia or MCI, especially in cases characterized by an older age of onset, lack of melancholic features, or absence of a family history of psychiatric disorders.