Cognitive impairment is now established as an impor- tant part of the clinical picture of schizophrenia, where it affects particularly though by no means exclusively exec- utive function, long-term memory, and sustained atten- tion.1,2 Although varying widely in severity from patient to patient, the degree of impairment is on average sub- stantial,3 and there is increasing evidence that it accounts for a signi cant part of the social and occupational functioning disability seen in the disorder.4,5 A variety of pharmacological treatments aimed at improving schizo- phrenic cognitive impairment have so far demonstrated only marginal ef cacy.6,7 An alternative, however, exists in cognitive remediation therapy (CRT),8,9 in which graded training is given on memory, executive, and sometimes other tasks. Improvement is expected to take place on the training tasks, and the aim is that this will generalize to other tasks in the same cognitive domains.
Over 40 trials of CRT in schizophrenia have now been carried out. Wykes et al10 meta-analyzed those carried out up to 2010 and found a pooled effect size of 0.45 in 38 studies which reported a measure of global cognition. Pooled effect sizes were also signi cant for verbal episodic memory (0.41, 23 studies), verbal working memory (0.35, 20 studies), reasoning/problem solving (0.57, 24 stud- ies), and speed of processing (0.26, 24 studies). Against these encouraging ndings, however, a recent large and methodologically rigorous trial has had negative ndings. Dickinson et al11 randomly assigned 69 schizophrenic patients to either computerized CRT or a control inter- vention consisting of other computer activities. Both treatment conditions were manualized; the patients were not informed whether the one they were assigned to…..