Highlights
- •Individuals with schizophrenia commonly have cognitive impairments, which predict longer-term functional outcomes.
- •The key dysfunctional domains are memory and learning.
- •Combining transcranial direct current stimulation (tDCS) and cognitive training (utilising both working memory (WM) and implicit learning (IL) tasks), improves cognitive deficits in patients with schizophrenia.
- •This is the first study to show a significant longer-term effect of tDCS on WM in schizophrenia.
- •tDCS may offer an important approach to ameliorate cognitive deficits in schizophrenia.
Abstract
Background
Schizophrenia is characterized by prominent cognitive deficits, impacting on memory
and learning; these are strongly associated with the prefrontal cortex.
Objective/hypothesis
To combine two interventions, transcranial direct current stimulation (tDCS) over
the prefrontal cortex and cognitive training, to examine change in cognitive performance
in patients with schizophrenia.
Methods
A double blind, sham-controlled pilot study of 49 patients with schizophrenia, randomized
into real or sham tDCS stimulation groups. Subjects participated in 4 days of cognitive
training (days 1, 2, 14, 56) with tDCS applied at day-1 and day-14. The primary outcome
measure was change in accuracy on working memory and implicit learning tasks from
baseline. The secondary outcome measure was the generalization of learning to non-trained
task, indexed by the CogState neuropsychological battery. Data analysis was conducted
using multilevel modelling and multiple regressions.
Results
24 participants were randomized to real tDCS and 25 to sham. The working memory task
demonstrated a significant mean difference in performance in the tDCS treatment group:
at day-2 (b = 0.68, CI 0.14–1.21; p = 0.044) and at day-56 (b = 0.71, 0.16–1.26; p = 0.044).
There were no significant effects of tDCS on implicit learning. Trend evidence of
generalization onto untrained tasks of attention and vigilance task (b = 0.40, 0.43–0.77;
p = 0.058) was found.
Conclusions
This is the first study to show a significant longer-term effect of tDCS on working
memory in schizophrenia. Given the current lack of effective therapies for cognitive
deficits, tDCS may offer an important novel approach to modulating brain networks
to ameliorate cognitive deficits in schizophrenia.
Keywords
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Article info
Publication history
Published online: December 27, 2016
Accepted:
December 23,
2016
Received in revised form:
October 7,
2016
Received:
June 16,
2016
Identification
Copyright
© 2016 Elsevier Inc. All rights reserved.
