Measuring psychomotor agitation via hand tremor in remitted major depressive disorder.

Psychomotor agitation (PmA), a common yet understudied symptom in Major Depressive Disorder (MDD), is characterized by heightened motor activity such as restlessness and fidgeting. PmA, like other symptoms of MDD, may persist into remission. This study examined the role of PmA in remitted MDD by using a novel smartphone based physiological measure of tremor. Participants (N = 157) consisted of healthy controls (N = 76) and those with remitted MDD (N = 81, to reduce the impact of current MDD symptoms on PmA), and tremor was assessed under the manipulation of position (palm-up, arm extended) and cognitive load (no cognitive load, cognitive load). Individuals with remitted-MDD exhibited a distinct pattern from HCs: specifically, greater tremor under high cognitive load compared to no cognitive load, while HCs showed lower tremor under cognitive load compared to no cognitive load. These findings suggest that tremor is sensitive to cognitive demands, and that tremor may provide an objective, physiological marker of PmA in remitted MDD. More generally, our results highlight the importance of using instrumental measures to assess PmA.