Psychomotor disturbances are among the core symptoms of endogenous depression. They reflect the underlying pathophysiology of the depressive episode and are sensitive to the neurobiological effects of its pharmacological treatment. Being objectively manifested, the psychomotor functions and dysfunctions are technically recordable and measurable by the available motion analysis systems.

To objectively record and measure the psychomotor dysfunctions in bipolar depression and their dynamics during pharmacological treatment.

We introduced an original (internationally patented) equilibriometric method for objective and quantitative recording of psychomotor dysfunctions during stepping locomotion in 37 hospitalized patients with bipolar depression and 30 well-matched healthy controls. Two separable psychomotor functions were analyzed in parallel: conscious (voluntary) activity and subconscious (automatic) reactivity. Both patients and controls were examined twice in order to quantify their psychomotor dynamics. Patients were examined at the first day of their hospitalisation and the day before their discharge. The two consecutive examinations of the controls were with equivalent time intervals.

There was no significant psychomotor dynamics (P > 0.05) in the healthy controls between their first and second equilibriometric recording. Psychomotor activity and/or reactivity of the patients were relatively slower at their first recording and significantly accelerated (P < 0.05) at their second recording after effective pharmacological treatment.

Objective recording and quantitative assessment of psychomotor dynamics in patients with bipolar depression during the pharmacological treatment of their current episode could be a sensitive measure of their improvement and might be used as a surrogate pharmacodynamic biomarker for objective treatment monitoring.

The authors have not supplied their declaration of competing interest.