Long-term course of negative symptom subdomains and relationship with outcome in patients with a psychotic disorder.

BACKGROUND: The longitudinal course of the negative symptoms subdomains social amotivation (SA) and expressive deficits (ED) remains largely unknown. We investigated i) the longitudinal course of SA and ED subdomain scores, ii) whether subgroups based on the course of SA and ED subdomain scores could be identified, iii) whether baseline SA and ED subdomain scores were related to functioning and quality of life six years later and iv) the longitudinal relationship between subgroups and outcomes.

METHODS: Measurements at baseline, three and six years from 1067 patients participating in the Genetic Risk and Outcome of Psychosis (GROUP) project were used. We applied mixed models analysis, regression analysis and trajectory analyses.

RESULTS: SA and ED subdomain scores decreased over time. Within both subdomains, four subgroups were identified: for both SA and ED a steady low course (±60%), increased (±15%) and decreased course (±15%). Within SA only, a higher level decreased course (±6%) and within ED only, a course with relatively stable high ED scores (±6%) was found. Lower symptom levels at baseline were related to better functioning (SA & ED) and quality of life (SA) at six years. Overall, low SA and low ED subgroups showed better outcomes than the other subgroups.

CONCLUSION: In many patients the course of negative symptoms is unstable and related to the course of outcome. Patients who do show steady low negative symptom levels (60%) may complicate the interpretation of treatment evaluation studies, as they may average out possible effects in subgroups with fluctuating symptom levels.