Comparative effects of yoga and aerobic exercise combined with transcranial direct current stimulation on cognition in psychosis

Background

Cognitive and functional impairments are central features of psychotic disorders. These symptoms often persist even after symptoms are managed with pharmacological treatment. To address this problem, non-pharmacological interventions such as transcranial direct current stimulation (tDCS) and physical exercise are used as promising combined treatments which may enhance neuroplasticity and improve cognitive outcomes. However, the optimal modality and duration for combined interventions remain unclear. This abstract synthesizes findings from two independent pilot trials exploring different exercise-tDCS paradigms: Aerobic Exercise (AE) and Yoga.

Methods

The investigation comprised two distinct protocols. Study 1 (The Yoga-tDCS Pilot) was a randomized sham-controlled trail involving 18 participants with chronic schizophrenia. Participants were randomized into 2 arms: 2-week active tDCS + yoga (n=9) or 2-week sham tDCS + yoga (n=9). Interventions were conducted five days per week for two weeks. Study 2 (The AE-tDCS Pilot) was a non-randomized pilot study involving 10 individuals with psychosis and 11 healthy controls. Participants completed a 6-week waitlist control period, followed by a 6-week intervention of AE combined with tDCS. Assessments were conducted at baseline (T0), post-waitlist (T1), and post-intervention (T2). Outcome measures for both studies included cognitive tests, quality of life, and clinical symptoms. The primary outcome was executive function measured by the Verbal Fluency Test (VFT).

Results

In Study 1, 16 participants completed the trial with an 11% attrition rate. The active tDCS + yoga group showed a small-to-medium effect in executive function (VFT, Cohen’s d=0.39) compared to the sham tDCS + yoga group. A significant time × group interaction was found for physical function (36-Item Short Form Survey, Cohen’s d=0.61), favoring the active tDCS + yoga group. Both groups showed trends toward improved working memory and clinical symptoms (Cohen’s d=0.21 to 0.55). In Study 2, 15 participants (8 psychosis, 7 healthy) completed the study with an average dropout rate of 28%. Among individuals with psychosis, VFT scores significantly improved after the 6-week intervention (P=0.007). Significant reductions were observed in negative (P=0.008) and general psychotic symptoms (P=0.011), alongside significant gains across five functioning domains (all P<0.05). Effect sizes ranged from moderate to large (Cohen’s d=-0.47 to -0.84). Healthy subjects showed a non-significant trend toward improvement.

Conclusions

These pilot studies indicate that combining tDCS with either aerobic exercise or yoga is a feasible approach for cognitive remediation in psychosis. The 2-week Yoga-tDCS protocol demonstrated superior physical functioning and a positive trend in cognitive gains despite its short duration. The 6-week AE-tDCS protocol was developed based on the positive preliminary results of the 2-week Yoga-tDCS trail to evaluate if longer combined treatment could further narrow the cognitive gap between patients and healthy controls. As expected, the 6-week AE-tDCS protocol yielded comparable improvements in executive function and clinical symptoms. These findings suggest that both aerobic and mind-body exercises can effectively serve as platforms for neuromodulation, providing a basis for larger trials to optimize intervention parameters.

References

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