The different neurological characteristics of "psycho" and "motor" retardation in depression: A perspective from the subdivision of the striatum.

Psychomotor retardation (PMR) is a core feature of major depressive disorder (MDD), yet its neural substrates remain elusive. We hypothesized that aberrant striato-cortical connectivity differentially underlies the cognitive and motor components of PMR. In a case-control study, 172 PMR patients, 387 non-PMR patients, and 297 healthy controls were examined using a gray matter-white matter-gray matter (G-W-G) connectivity model. The dataset was split into primary (80%) and validation (20%) sets. In both sets, the PMR group showed reduced connectivity between the left dorsolateral prefrontal cortex and bilateral ventral striatum (negatively associated with cognitive retardation), and enhanced connectivity between the right primary motor cortex and bilateral dorsal striatum (positively associated with motor retardation). These findings demonstrate that distinct striato-cortical pathways differentially contribute to PMR subcomponents, with cognitive retardation linked to disrupted cognitive control circuits and motor retardation to hyperconnectivity in motor pathways.