Wearable technology to assess bradykinesia and immobility in patients with severe depression undergoing electroconvulsive therapy: A pilot study

The psychomotor retardation that may be seen in major depression represents an interesting parallel to bradykinesia, a core feature of Parkinson's disease. Psychomotor retardation has been correlated with the severity of depression and is a predictor of response to electroconvulsive therapy (ECT). Psychomotor retardation has typically been assessed by subjective clinical judgement including clinical rating scales. Gross activity levels have also been measured with actigraphy previously. The Parkinson's KinetiGraph (PKG) was developed to assess bradykinesia, dyskinesia and tremor in Parkinson's disease and allows for an objective assessment of motor symptoms over time. It has not been used previously to assess motor symptoms in depression. The aim of the current pilot study was to use the PKG to objectively measure both bradykinesia and immobility in depressed inpatients undergoing ECT before, during and at the end of therapy and review correlations with depressive symptomatology and treatment response. The majority of patients (9/12) had PKG defined bradykinesia at baseline and 7/9 of these improved with ECT. All patients with bradykinesia who remitted clinically demonstrated improvements in bradykinesia scores. PKG defined immobility was present at baseline in 11/12 total patients and improved in the majority of these patients (9/11) post ECT. Correlations between clinically assessed melancholia and PKG measures were significant (r = 0.701, p 0.011 at baseline to r(s) = 0.655, p 0.021 at end). A strong association between bradykinesia and immobility scores and depression severity was not seen. The PKG is a potentially useful wearable technology to objectively assess motor symptoms in depression.