Long-Term Durability of Cognitive Enhancement Therapy Effects in Early Course Schizophrenia

Background and Purpose: Cognitive rehabilitation approaches, including Cognitive Enhancement Therapy (CET), have been shown to improve cognitive and functional recovery among individuals with early course and long-term schizophrenia. Current evidence indicates that the introduction of cognitive rehabilitation soon after the development of schizophrenia may substantially reduce the disability associated with the condition, however the long-term effects of such approaches on cognitive and functional outcomes are largely unknown. This study sought to examine the long-term impact of CET applied in the early course of schizophrenia, and the degree to which gains demonstrated at the end of treatment continue to be observed in the following decade after treatment completion.

Methods: Individuals in the early course of schizophrenia (N = 58) who were treated as outpatients in a 2-year randomized clinical trial of CET were followed-up on average 10 years after study completion. A comprehensive battery of cognitive, functional, and clinical assessments identical to those in the original trial were collected at 10-year follow-up by raters who were blind to treatment assignment. Composite indexes were calculated for the main study outcomes of neurocognition, social cognition, functioning, and symptomatology. Linear growth curve models were used to examine the longitudinal durability of effects on these domains 10-years following treatment with either CET or an Enriched Supportive Therapy (EST).

Results: A total of 37 of the 58 (64%) original clinical trial participants completed follow-up data collection. Those lost to follow-up included 10 participants who were not interested, 5 who were deceased, 3 who were living out of the area, 2 who were incarcerated, and 1 participant who was too symptomatic to complete assessments. There were no significant differences in follow-up rates between treatment groups (p = .386). Intent-to-treat linear growth curve models indicated that participants treated with CET demonstrated significantly greater social-cognitive ability at follow-up than those treated with EST (d = 1.14, p < .001). Although decrements in gains in functioning and symptomatology were clearly observed in both treatment conditions during the follow-up period, growth models including all study timepoints continued to show a moderate advantage of CET for improving functional outcomes (d = .54, p < .001) and reducing symptomatology (d = -.33, p = .048) compared to EST. Differential effects favoring CET for improving neurocognition were not maintained at follow-up (d = .09, p = .124).

Conclusions and Implications: This first, long-term study of the durability of cognitive rehabilitation effects in the early course of schizophrenia suggests that the benefits of CET to social cognition may last for a decade after the completion of treatment. Effects on neurocognition, functional outcome, and symptomatology were less durable. These findings indicate that CET may have potentially long-lasting effects on social information processing when applied in the early course of schizophrenia, and also signify the need for developing booster cognitive rehabilitation strategies to promote the maintenance of gains in other domains as individuals transition from the early to later phases of the condition.