Background: Schizophrenia with an onset in adolescence is known to be associated with a poorer outcome and cognitive difficulties. These impairments have an impact on quality of life and represent treatment targets. Cognitive remediation therapy (CRT) attempts to improve cognitive deficits by teaching information processing strategies through guided mental exercises. The objective of this study is to evaluate the efficacy of CRT in alleviating cognitive deficits compared to treatment as usual and explore the mediating and moderating effects of cognitive improvement.
Method: Single-blind randomized controlled trial with two groups, one receiving CRT (N21) and the other standard care (N19) assessed at baseline, 3 months (post therapy) and follow-up (3 months post therapy). Participants were recruited from specialist inpatient and community mental health services and were young patients with recent onset schizophrenia (average age of 18) and evidence of cognitive and social behavioural difficulties. The intervention was individual cognitive remediation therapy delivered over a period of 3 months with at least three sessions per week. The main outcome measures were cognition (memory, cognitive flexibility and planning) and secondary outcomes (symptoms, social contacts and self-esteem).
Results: Compared to standard care, CRT produced significant additional improvements in cognitive flexibility as measured by the Wisconsin Card Sort Test (WCST). Therapy moderated the effects of improved planning ability on symptoms such that improvements only had a beneficial effect when they were achieved in the context of CRT. Improvements in cognition in all domains had a direct effect on social functioning and improvements in WCST had a direct effect on overall symptom improvement.
Conclusions: Cognitive remediation therapy can contribute to the improvement in WCST even in adolescents. The changes in cognitive outcomes also contributed to improvements in functioning either directly or solely in the context of CRT. Evidence of the mediator and moderator effects of cognitive changes should lead to more effective therapy development.