Boosting and maintaining the response to transcranial direct current stimulation (tDCS) in schizophrenia with persistent hallucinations: A retrospective exploratory study from a naturalistic clinical cohort.

BACKGROUND

Transcranial direct current stimulation (tDCS) may help to alleviate persistent auditory hallucinations (AH) in schizophrenia, though its effects vary. This study examines the effectiveness, replicability and tolerance of booster and maintenance tDCS courses administered to patients with schizophrenia in a naturalistic clinical setting after an initial tDCS course.

METHODS

Thirty-three patients received booster course(s) (after symptom relapse) and/or maintenance courses (to prevent relapse) following an initial course of 2-15 days. Linear mixed-effect (LME) model and intra-class correlation (ICC) evaluated the differences and consistency of percentage improvement in AH across the initial and booster courses. The duration between the initial and the first booster course served as a proxy for time to relapse, with its relationship to clinical and demographic measures analyzed using Pearson's correlation.

RESULTS

The booster course was safely administered in 33 patients, 22 weeks after the initial course. AH improved significantly in 20 patients. The improvement percentages for the initial (43.6 %) and the booster courses (29.3 %) had an ICC of 0.711 (95 %CI:0.372-0.868, p < 0.001), suggesting moderate replicability of effects. The LME model revealed that course type and number of tDCS sessions significantly influenced improvement. Maintenance tDCS was administered in 5 patients at 1-4 week intervals, with 2 maintaining improvement.

CONCLUSION

This study offers insights into the likely duration of initial tDCS effects and highlights the utility of booster courses for individuals who responded to the initial treatment. The study suggests the possibility of using maintenance tDCS in patients who have responded to the initial or booster treatments.