Negative symptoms reflect one of the most debilitating aspects of one of the most debilitating diseases known to humankind. As yet, our treatments for negative symptoms are palliative at best and our understanding of their causes is relatively superficial. To address this, we are developing objective ambulatory tools for digitally phenotyping their severity which can be used outside the confines of the traditional clinical and research settings. The present study evaluated the feasibility, reliability and validity of ambulatory vocal acoustic and facial emotion expression analysis. Videos were provided by 25 patients with schizophrenia or schizoaffective disorder and 27 nonpsychiatric controls using inexpensive, non-invasive ambulatory recording methods. Controls provided 411 video recordings, and patients provided 377 video recordings; an average of 15.22 and 14.50 per participant per group respectively. The vast majority (over 80%) of these videos were usable for analysis. An empirically-supported, limited-feature vocal (7 features) and facial (3 features) set was examined. Within participants, these features varied considerably over time, but showed moderate to good test-retest reliability in many cases once contextual factors (e.g., activity involved in at the time of testing) were accounted for. Vocal and facial features showed statistically significant convergence with a "gold standard" negative symptom measure. Ambulatory vocal/facial features were more strongly associated with engagement in social or work activities in patients than negative symptom ratings. These data support the use of ambulatory vocal/facial analytic technologies for digital phenotyping of these negative symptoms.
Keywords: Ambulatory assessment; Digital phenotyping; Facial emotion expression; Negative symptoms; Vocal acoustic expression.
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