The effect of transcranial direct current stimulation on emotion-related risk-taking behaviour and delay discounting in adult patients with attention deficit hyperactivitydisorder

AIM: Attention Deficit Hyperactivity Disorder(ADHD) is a neurodevelopmental disorder that usually begins in childhood and is characterised by difficulties in attention, hyperactivity and impulsivity symptoms as well as impaired academic and social functioning. It is observed that patients with ADHD continue to have complaints in adulthood and they have risky decision-making behaviour. Our aim was to determine the effects of Transcranial Direct Current Stimulation(tDCS) on impulsivity, risk-taking behaviours and delay discounting in this group. It is also aimed to investigate the effects of reward magnitude, positive and negative emotions on risk-taking behaviours and delay discounting in adult ADHD patients under different tDAU conditions. MATERIALS AND METHODS: The study included 30 volunteer patients aged between 18-45 years who were diagnosed with ADHD according to DSM-5 diagnostic criteria. Diagnostic Interview for ADHD in Adults-5(DIVA-5), Adult ADHD Self-Report Scale (ASRS), Hyperfocusing Scale(HS), Wender Utah Rating Scale(WURS) were used to evaluate ADHD symptoms; Difficulty in Emotion Regulation Scale-Short Form(DERS-16) was used to evaluate symptoms related to emotion regulation, and Trail Making Test A and B were used to evaluate executive functions. Left DLPFC anode/right VMPFC cathode, left DLPFC cathode/right VMPFC anode, and sham tDAUs were administered to all participants in randomised order and at least one week apart. In each session, the participants were shown 5 photographs with sounds added to evoke neutral, positive and negative emotions, during which the Galvanic Skin Response(GSR) of the participants was also measured. After each emotional stimulation, Delay Discounting Task(DDT) and Modified Balloon Analogue Risk Task(M-BART) were applied. During the DDT, participants were asked questions about small, medium and big rewards. Following each session, a questionnaire was administered to the participants for tDAU-related side effects. RESULTS: Participants' mean GSRs were significantly higher for negative condition compared to positive, and for positive condition compared to neutral condition. Participants' subjective evaluations regarding the valance and the arousal levels of the photographs were also consistent with the findings of the GDT. It was found that the AUC under neutral condition was significantly lower than that under negative condition. In addition, AUC100 and AUC1000 were significantly lower than AUC10000, but there was no significant difference between AUC100 and AUC1000. For the left DLPFC cathode/right VMPFC anode and sham conditions of tDAU, AUC100 and AUC1000 were lower than AUC10000. For the left DLPFC anode/right VMPFC cathode condition, AUC1000 was significantly lower than AUC10000. AUC100 under the left DLPFC anode/right VMPFC cathode condition was higher than AUC100 under the left DLPFC cathode/right VMPFC anode condition, but this result approached statistical significance. According to the results of the M-BART experiment, BART-C score was found to be higher in left DLPFC anode/right VMPFC cathode stimulation and left DLPFC cathode/right VMPFC anode stimulation compared to sham stimulation. CONCLUSIONS: This study found that although tDAU had a significant effect on some decision-making and risk-taking variables in adults with ADHD, it was not consistently effective. Also, in parallel with the previous studies it was observed that increased amount of reward size reduced risky decision making in this sample. However, negative emotional stimulation in GIG led to more protective decisions. In future studies, it is recommended to examine the effect of repeated tDAU on risk-taking behavior in ADHD cases and to check its effects on related brain regions with a neuroimaging method.