Enhancing positive memory schemas with tDCS: a pilot study

Abstract

Negative schemas during depression drive persistent memory biases. Positive mood induction procedures (MIPs) can briefly counteract these but are often short-lived. Non-invasive brain stimulation (NIBS) may enhance MIPs. We tested whether anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC), compared to sham tDCS, could strengthen and prolong MIPs effects on mood and resulted in weaker negative memory bias. For this sham-controlled, within subject counterbalanced study we selected twenty dysphoric participants (BDI-II > 13). Mood state was assessed via visual analogue scales before and after the MIP and at session end. Memory was assessed using the Deese-Roediger-McDermott (DRM) false-memory task and a Self-Referent Encoding Task, measuring recall accuracy, recognition indices (hits, false alarms, d′), and self-referent memory bias. Results Condition and time did not interact on mood states in this pilot study. However, exploratory analyses revealed that active tDCS significantly reduced sadness at the final time point compared to sham tDCS. The active tDCS condition resulted in less false recognition of negative words in the DRM Task, but condition and valence interaction were non-significant for hit rates. Participants in the active tDCS condition better discriminated critical lures and recalled more words overall. tDCS over the DLPFC may prolong MIP effects, reduce negative memory bias and promote more positive schema processing. These findings support integrating NIBS with personalised MIPs as a promising avenue for decreasing depression characteristics. Future work should test repeated tDCS, larger samples, and ecologically valid memory bias and mood assessments to strengthen clinical relevance.