Digital phenotyping for differential diagnosis of Major Depressive Episode: A literature review (Preprint)

UNSTRUCTURED Major depressive episode (MDE) is a common clinical syndrome. It can be found in different pathologies such as mood depressive disorder (MDD), bipolar disorder (BD), post-traumatic stress disorder (PTSD) or even occur in a context of psychotrauma. However, only one syndrome is described in international classifications (DSM 5/ICD 11) which do not take into account the underlying pathology at the origin of the MDE. Clinical interviews are currently the best source of information to obtain the etiological diagnosis of MDE. Nevertheless, it does not allow an early diagnosis and there are no objective measures of extracted clinical information. To remedy this, the use of digital tools and their correlation with clinical symptomatology seems promising. We review the state of the art on the use of digital tools during clinical interviews for etiological diagnosis of MDE. For this purpose, we were interested in four frequently found clinical conditions in which MDE can occur: MDD, BD, PTSD and/or trauma investigated by the means of automated voice analysis, behaviour analysis by video and physiological measures by heart rate variability (HRV) and electrodermal activity (EDA). This paper gives a detailed overview of studies on different digital markers associated with MDE which could be useful for differential diagnosis. A digital phenotype of MDE seem to emerge consisting of modifications in speech features (namely temporal, prosodic, spectral, sources, formants and in speech content), modifications in nonverbal behaviour (Head, hand, body and eyes movement, facial expressivity and gaze) and a decrease in physiological measurements (HRV and EDA). We found similarities but also differences when MDE occur in MDD, BD or PTSD. However, comparative studies were rare in BD or PTSD conditions which do not allow us to identify clear and distinct digital phenotypes. Our search identifies markers from several modalities that hold promise for an objective etiological diagnosis of MDE. To validate their potential, further longitudinal and prospective studies are needed.