Evaluating the relationship between speech production variability and psychomotor dysfunction in individuals with major depressive disorder

Individuals with many disorders, including major depressive disorder (MDD), often experience motor symptoms (psychomotor dysfunction). These symptoms include slowing (psychomotor retardation; PmR) and jerkiness or restlessness (psychomotor agitation; PmA). Previous work has assessed these using non-speech motor tasks, such as drawing circles quickly (indexing PmR) and smoothly (indexing PmA), or holding a steady degree of force when pressing a button (indexing PmA). The goal of this study was to test whether PmR and PmA are instantiated similarly in speech as in these non-speech motor tasks. Participants with current MDD, remitted MDD, and healthy controls completed the alternating motion rate diadochokinetic speech task, quickly repeating single syllables (/pa/, /ta/, /ka/). Syllable length (release of the consonant to vowel offset) and inter-syllable pause duration were annotated within each trial. Preliminary results support similar instantiation of motor symptoms across speech and non-speech tasks. Individuals with higher phonation rate (speaking time, excluding pauses, divided by total trial time) showed greater velocity when drawing circles. Independently, individuals with greater variability in inter-syllable pause durations had greater force variability (in the button press task) and jerk (degree of agitation in hand movement when drawing). The relationship between these motor measures and depression symptomology will be discussed.