The Digit-Symbol Substitution Test (DSST) is a cognitive test designed to assess psychomotor speed of performance requiring visual perception, spatial decision-making and motor skills. The DSST is sensitive to cognitive impairments affecting attention, processing speed, and executive function (including working memory). The DSST consists of 133 digits and requires the subject to substitute each digit with a simple symbol in a 90-second period. Each correct symbol is counted. The total score is the number of correct symbols and the total score ranges from 0 (less than normal functioning) to 133 (greater than normal functioning).

The Oxford Depression Questionnaire (ODQ) is a patient-centred, self-report measure of emotional symptoms present in patients treated with antidepressants. The ODQ is a 26-item patient self-complete measure, spread over 3 sections and covering 5 dimensions of: not caring (NC), emotional detachment (ED), positive reduction (PR), general reduction (GR), and antidepressant as cause (AC). Response options are based on 5-point Likert scale with a score applied to each response.

The Montgomery and Åsberg Depression Rating Scale (MADRS) is a 10-item rating scale designed to assess the severity of the symptoms in depressive illness and to be sensitive to treatment effects. Symptoms are rated on a 7-point scale from 0 (no symptom) to 6 (severe symptom). The total score of the 10 items ranges from 0 to 60, with higher values indicating worse outcome.

Sheehan Disability Scale (SDS) measures disability. Total scores are computed by summing scores from all 3 items. Total score ranges from 0 to 30, with higher scores indicating greater disability. Reduction in SDS scores therefore indicates better outcome.

Sheehan Disability Scale (SDS) measures disability. Total scores are computed by summing scores from all 3 items. Total score ranges from 0 to 30, with higher scores indicating greater disability. Reduction in SDS scores therefore indicates better outcome.

The Clinical Global Impression severity of illness (CGI-S) provides the clinician's impression of the patient's current state of mental illness. The clinician uses his or her clinical experience of this patient population to rate the severity of the patient's current mental illness on a 7-point scale ranging from 1 (normal - not at all ill) to 7 (among the most extremely ill patients).

The Clinical Global Impression - global improvement CGI-I provides the clinician's impression of the patient's improvement (or worsening). The clinician assesses the patient's condition relative to a baseline on a 7-point scale ranging from 1 (very much improved) to 7 (very much worse). In all cases, the assessment should be made independent of whether the rater believes the improvement is drug-related or not.