Interval Versus Continuous Cognitive Training in Schizophrenia: Comparing Cognitive, Neurophysiological, and Subjective Outcomes
Schizophrenia , Cognitive Remediation , Spacing Effect , Rest , Working Memory
Background: Therapies aimed at remediating cognitive deficits in schizophrenia vary widely in their approach and delivery of cognitive training. In healthy populations, rest breaks have been shown to improve attention, performance, and subjective experience of work or cognitive tasks. Neurophysiological research has demonstrated a relationship between on-task band power, performance, and working memory load. Objectives: The current study aimed to assess the effect of rest breaks during cognitive training in schizophrenia through examination of cognitive performance and improvement, mean theta and alpha power, and subjective measures focused on acceptability and intrinsic motivation. Methods: 24 participants with schizophrenia completed three working memory tasks to assess baseline functioning and were randomized into either interval or continuous cognitive training on the N-back task, each with a total of 10-minutes of on-task training. Immediately following training, subjects completed the three working memory tasks again to assess immediate change in performance, and again following a 30-minute period of respite to assess durable change. Continuous EEG was recorded throughout, and following completion participants’ subjective experience of training was assessed with a self-report questionnaire. Results: The interval training group performed significantly better than the continuous training group during the training period, however this did not lead to improvement differences at post-testing on the training task. For tasks not trained on, there was a trend for significantly greater improvement following interval training with medium effect size. No differences were observed in theta or alpha band power between groups during training, nor was band power found to be significantly correlated with task difficulty or performance. There were no significant differences between groups for subjective training experience. Discussion: Results suggest that incorporating rest intervals in cognitive training leads to greater performance during training and enhanced skills transfer to other domains of working memory. This observation could be due to memory retention benefits of the spacing effect in the interval condition. Alternatively, results could be due to mental fatigue and/or ego depletion in the continuous condition, leading to a reduced capacity for performance and improvement on non-trained tasks. Further research is needed to determine the underlying mechanism of improvement and transfer.