Chronobiology and Depression: Circadian Analytics as a Biomarker for Depressive Subtypes

This longitudinal, two-phase, three-arm, exploratory, observational study will use the Medibio analytics platform-with heart rate, activity, postural, and EEG data inputs-to characterize autonomic, circadian, and sleep patterns in unipolar depressed and bipolar depressed patients, which will include those with atypical and melancholic subtypes, undergoing the initial phase of standard pharmacological treatment, as well as in a non-depressed control group. Phase I will serve as a non-blinded, discovery phase for Medibio algorithm development. Phase II is optional, based upon sponsor/investigator assessment of results from Phase I. Phase II procedures will be identical to those in Phase I, with the exception that the Medibio algorithm will be blinded to clinical classification and status. The study cohorts will comprise: a) individuals initiating standard pharmacologic therapy with SSRIs for moderate-to- severe unipolar depression (will include subjects with melancholic and atypical subtypes), b) individuals initiating standard pharmacologic therapy with lamotrigine, lithium, or valproate for moderate or severe bipolar I or II depression (will also include subjects with melancholic and atypical subtypes), and c) non-depressed individuals who have been matched at the group level for age and gender (control subjects). Before the commencement of pharmacologic therapy (Baseline, t=0), at t=4 weeks, and at t=8 weeks, heart rate, activity, postural data will be collected using the Zephyr BioPatch (Medtronic, Inc.) and ambulatory EEG data will be collected using the ZMachine Insight (General Sleep Corp). Recordings at each time point will consist of three 24-hour Zephyr recordings and three overnight ZMachine recordings. Clinical assessments will also be captured at the same time points, comprising both clinician-administered instruments \[Clinical Global Impression (CGI), Hamilton Depression Rating Scale-17 (HAMD-17), and Young Mania Rating Scale (YMRS)\] and subject self-rated instruments \[Patient Health Questionnaire-9 (PHQ-9) and Quick Inventory of Depressive Symptomatology-Self Report (QIDS SR16)\]. Zephyr and ZMachine data will be filtered based on quality (duration and completeness) and may be 'de-noised,' then will be processed by the Medibio platform to generate autonomic, circadian, and sleep metrics for use in the statistical analysis of study results.