Effectiveness of transcranial direct current stimulation (tDCS) on attention and memory biases in individuals with post-traumatic stress disorder (PTSD): a randomized, single-blind, parallel-group study.

Based on neurocognitive models, the development and maintenance of post-traumatic stress disorder (PTSD) are correlated with cognitive biases, including attention and memory biases, which are associated with imbalanced activation of prefrontal regions, particularly the dorsolateral prefrontal cortex (dlPFC). The present study investigated how modulation of the dlPFC could lead to cognitive bias modification in war veterans with PTSD. We explored the effectiveness of 10 sessions of anodal tDCS over the left dlPFC concurrent with cathodal tDCS over the right dlPFC on attention and memory biases in 30 male war veterans with PTSD. The participants were randomly assigned to "real" and "sham" groups in a randomized, single-blind, parallel-group design. They underwent 10 sessions of real (2 mA, 20 min) or sham tDCS over five consecutive days. We measured participants' performance on attention bias (emotional Dot-probe and emotional Stroop tasks) and memory bias (autobiographical memory test) at pre-test, post-test, and 1-month follow-up stages. The results showed significant improvement in autobiographical memory bias in the tDCS group at both the post-test and follow-up stages compared to sham group. However, no significant effect of tDCS was observed on attention bias. Furthermore, within the tDCS group, the degree of improvement in memory specificity was correlated with a reduction in intrusion symptoms, providing preliminary evidence that modifying this cognitive bias may directly impact a core clinical feature of PTSD. Given the sample size and high variability of attentional measures, these null findings should be interpreted with caution and do not definitively rule out an effect of tDCS on attentional processes. In conclusion, tDCS over the dlPFC could improve imbalance between neural networks and cortical regions involved in autobiographical memory bias in PTSD; however, further studies are required to confirm these findings.