Interpersonal and Social Rhythm Therapy for Patients With Major Depressive Disorder. American journal of psychotherapy OBJECTIVE:This study aimed to conduct a safety analysis among patients with major depressive disorder receiving interpersonal and social rhythm therapy (IPSRT) with and without cognitive remediation. METHODS:This preliminary safety analysis of the outcomes of patients with major depressive disorder was part of a larger randomized controlled trial (RCT) in which patients with bipolar disorder and major depressive disorder received IPSRT; half were randomly assigned to receive additional cognitive remediation. The study focused on patients with major depressive disorder because IPSRT had not been trialed with this group; their outcomes were compared with those of patients with bipolar disorder. Data from the first 30 RCT participants were used to examine whether the intervention had adverse effects, whether mood symptoms and functioning improved over 12 months, and whether there was a signal of benefit. Mood symptoms were measured at baseline and 12 months with the Longitudinal Interval Follow-Up Evaluation and the Quick Inventory of Depressive Symptoms-Self-Reported; functioning was measured with the Social Adjustment Scale. RESULTS:A total of 63% (N=19) of participants were diagnosed with bipolar disorder and 27% (N=11) with major depressive disorder. No adverse effects were found for those with major depressive disorder, and improvements were seen in mean depressive and functioning scores at 12 months compared with baseline, with moderate to large effect sizes. CONCLUSIONS:IPSRT may be a clinically effective intervention for patients with major depressive disorder. Outcomes related to cognitive functioning and the effects of cognitive remediation will be reported at the end of the trial. 10.1176/appi.psychotherapy.20190024