The phase-oriented treatment approach is the widely recommended approach for Dissociative Identity Disorder (DID); however, evidence for brief, intensive outpatient delivery remains limited. This case report describes an intensive, time-limited, phase-oriented intervention in a client with DID comorbid with major depressive disorder and prominent somatic symptoms.

Following an initial clinical interview conducted according to DSM-5 diagnostic criteria and informed by information from a first-degree relative, a 41-year-old woman received an intensive outpatient phase-oriented treatment model across 17 sessions delivered over nine closely spaced days (two consecutive 50-minute sessions per treatment day; total 100 min). Symptom change was evaluated at baseline and at a 45-day follow-up using the Dissociative Experiences Scale (DES) and relevant subscales of the Dissociative Disorders Interview Schedule (DDIS). Long-term clinical follow-up was documented at 2, 3, and 8 years.

Dissociative symptoms decreased substantially from baseline (DES = 31.43) to the 45-day follow-up (DES = 6.07). On the DDIS depression subscale, endorsed items decreased from 9/9 at baseline to 1/9 at 45 days; on the somatic symptoms subscale, endorsed items decreased from 20/39 at baseline to 6/39 at 45 days. The reduction in somatic complaints was considered to have occurred in parallel with the integration of alternate identities characterized by pain and bodily distress. At the 8-year follow-up, despite experiencing several significant losses and stress, the DES score went up to 25, with some increases in the DDIS depression (5/9) and somatic symptoms (14/39) subscales, but still stayed below the initial levels of dissociation, depression, and somatic symptoms.

This case suggests that an intensive, time-limited, phase-oriented model may be feasible and associated with clinically meaningful short-term symptom reduction in DID with depressive and somatic features. Long-term follow-up indicates that gains may be broadly maintained yet sensitive to major stressors. Further systematic research is warranted.