The history of psychomotor symptoms in depression and its implications for modern neuroscience

Motor signs have been central to descriptions of melancholia since antiquity, yet their significance and presumed causes have varied considerably across history. Until today and despite their robust link with worse outcomes, the origin of motor signs in mood disorders is not well understood. This may be due to a lack of clinical awareness, heterogenous terminology and divergent assessment of motor signs in psychiatric and neurological research. In this paper, we revisit historical accounts of motor signs in melancholia, tracing their evolution from classical antiquity to the mid-20th century. Using a semi-systematic review of historical and clinical literature in four languages, we uncover ancient descriptions of motor retardation and agitation, initially framed within humoral and religious paradigms. From the 16th century onward, motor signs were increasingly interpreted as manifestations of problems in volition, affect and cognition caused by a nervous system dysfunction. By the 19th century, motor disturbance had become a defining feature of melancholia, giving rise to subtypes classifications that shaped early psychiatric nosology. Post–World War II developments introduced objective motor assessments and rating scales, yet conceptual disagreements persist regarding their definition, neuroanatomical correlates and attribution to affective, cognitive and motivational processes. We argue that historical perspectives offer valuable context for interpreting motor signs in contemporary neurobiological research. To advance the field, we propose a unified, non-interpretive motor vocabulary and advocate for the combined use of observer-rated and instrumented assessments.