The SHAPS is a 14-item participant-reported instrument which measures anhedonia. It has been shown to be valid and reliable in normal and clinical samples, with adequate construct validity, satisfactory test-retest reliability, and high internal consistency. The scale will be completed by the participant and reviewed by site personnel qualified to oversee completeness. Each of the 14 items has a set of 4 responses, 2 of which endorse agreement (Definitely Agree, Agree) and 2 of which endorse disagreement (Disagree, Strongly Disagree). A total score can be derived by summing the responses; items answered with strongly agree are coded as 1 while a strongly disagree response will be coded as 4. Therefore, scores on the SHAPS can range from 14 to 56, with higher scores corresponding to higher levels of anhedonia.

Change from baseline in PHQ-9 total score over time will be reported. The 9-item PHQ-9 scale scores each of the 9 symptom domains of the Diagnostic and Statistical Manual of Mental Disorders-5th Edition (DSM-5) diagnostic criteria for recurrent or single episode major depressive disorder (MDD) criteria and used both as a screening tool and a measure of response to treatment for depression. Each item is rated on a 4-point scale (0=not at all, 1=several days, 2=more than half the days, and 3=nearly every day). The participant's item responses are summed to provide a total score (range of 0 to 27), with higher scores indicating greater severity of depressive symptoms.

The PHQ-9 is a participant-rated assessment scale for the evaluation of depression symptoms over the past 2 weeks. The PHQ-9 is a reliable and valid measure of depression and depression severity. The questionnaire consists of 9 items and each item is scored from 0 to 3. Participants will be asked how often they have been bothered by symptoms over the past 2 weeks (Not at all [0], Several days [1], More than half the time [2], or Nearly every day [3]). Higher scores indicate higher levels of depression.

The HAM-A is a clinician-rated instrument administered to assess severity of anxiety, its improvement during the course of treatment, and the timing of such improvement. This instrument will be completed by qualified and trained Investigator site raters based on a semi-structured interview for his/her assessment of the participant. The scale consists of 14 items. Each item is rated on a scale of 0 (feeling not present) to 4 (very severe prevalence of the feeling). The HAM-A total score is the sum of the 14 items and the score ranges from 0 to 56.

Change from baseline in the CGI-S total score over time will be reported. The CGI-S evaluates the severity of psychopathology on a scale of 0 to 7. Considering total clinical experience, a participant is assessed on severity of mental illness at the time of rating according to: 0=not assessed; 1=normal (not at all ill); 2=borderline mentally ill; 3=mildly ill; 4=moderately ill; 5=markedly ill; 6=severely ill; 7=among the most extremely ill participants. The CGI-S permits a global evaluation of the participant's condition at a given time.

The CGI-I scale is a clinician-rated instrument that measures the improvement of the participant's symptoms of depression. It is a 7-point scale where a score of 1 indicates that the participant is "very much improved," a score of 4 indicates that the participant has experienced "no change," and a score of 7 indicates that the participant is "very much worse."

The SDS is a participant-rated instrument which was developed to assess functional impairment in 3 related domains of work/school, social, and family life. It is a brief self rated tool where the participant rates the 3 items on an anchored 10 point visual analog scale. Following the participant's self assessment, the rater should review the Work/School and Days Lost items to confirm appropriateness of the selected rating by evaluating the impact of MDD symptoms across those sectors. The SDS may be administered via telephone assessment; however, the participant must be provided with a portable document format (PDF) copy of the assessment for reference of the visual analog scale when selecting their ratings.