Geriatric Depression Mimicking Parkinson's Disease: A Case of Levodopa-Responsive Pseudoparkinsonism With a 3-Year Follow-Up.

Geriatric depression often presents with psychomotor retardation. Severe psychomotor retardation may manifest as pseudoparkinsonism, which mimics Parkinson's disease (PD) and is often difficult to treat with standard antidepressant therapy. We report a case of a woman in her 60s with recurrent major depression with melancholic features who remained symptomatic despite several months of vortioxetine augmented with aripiprazole. She developed overt parkinsonism, including asymmetric rest tremor, rigidity, bradykinesia, and postural instability, requiring wheelchair assistance (Hoehn and Yahr stage 5). A diagnostic trial of levodopa produced marked improvement in both motor and depressive symptoms, leading to a presumptive diagnosis of comorbid PD. However, a subsequent dopamine transporter scan (DaTscan) showed normal striatal uptake, which argued against neurodegeneration. The final diagnosis was considered most consistent with geriatric depression with pseudoparkinsonism. During the 3 years of follow-up, her depressive symptoms showed a clear temporal association with levodopa: symptoms worsened after discontinuation and remitted after reintroduction. This case highlights that pseudoparkinsonism in geriatric depression can closely mimic PD and that DaTscan may help exclude neurodegenerative parkinsonism. These findings also suggest that levodopa may be considered in selected cases of difficult-to-treat geriatric depression with pseudoparkinsonism.