Prefrontal cortical changes following cognitive training in patients with chronic schizophrenia: effects of practice, generalization, and specificity

Abstract

Cognitive training is increasingly used in the treatment of schizophrenia, but it remains unknown how this training affects functional neuroanatomy. Practice on specific cognitive tasks generally leads to automaticity and decreased prefrontal cortical activity, yet broad-based cognitive training programs may avoid automaticity and increase prefrontal cortex (PFC) activity. This study used quasi-randomized, placebo-control design and pre/post neuroimaging to examine functional plasticity associated with attention and working memory-focused cognitive training in patients with schizophrenia. Twenty-one participants with schizophrenia or schizoaffective disorder split into two demographically and performance matched groups (nine scanned per group) and nine control participants were tested 6-8 weeks apart. Compared with both patient controls and healthy controls, patients receiving cognitive training increased activation significantly more in attention and working memory networks, including dorsolateral prefrontal cortex, anterior cingulate and frontopolar cortex. The extent to which activity increased in a subset of these regions predicted performance improvements. Although this study was not designed to speak to the efficacy of cognitive training as a treatment, it is the first study to show that such training can increase the ability of patients to activate the PFC regions subserving attention and working memory.

Figures

Figure 1

Regions showing significantly greater post-test activity than pre-test activity for the REM group compared with the CBSST or the CON group in the word 2-back task and the picture 2-back task. No significant group differences between pre-test and post-test activity were found in the lexical decision task.

Figure 2

Change in functional activity in the regions of overlap in the 3-way interaction (load by time by group) between both the word and picture working memory tasks showing that in each region there is an increase in activity in the cognitive remediation group. (Effect size d for the difference in activity between the two patient groups at baseline were as follows: (a) Left dorsolateral PFC: word=−0.33; animal=0.56. (b) Anterior Cingulate: word=−0.40; animal=−0.17. (c) Left Dorsal PFC: word=0.13; animal=0.48 (d) Right Frontopolar PFC: word=−0.57; animal=0.09. (e) Left Frontopolar: word=0.01; animal=−0.55, in which a positive effect size mean REM had greater baseline difference in 2B-0B).

Figure 3

Regions of overlap in the three-way interaction (load by time by group) between both the word and picture working memory tasks showing activity increases in bilateral frontopolar regions, anterior cingulate cortex, and left dorsolateral/dorsal prefrontal cortex. Significant correlations between improved behavioral performance (x axis, percentage of increase) and increased functional activation (y axis, percentage of signal change) are also shown. Word 2-back is represented in red and picture 2-back in blue.