Combining repetitive transcranial magnetic stimulation with transcranial direct current stimulation in treating psychiatric conditions: A systematic review.

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) have been thoroughly explored in the treatment of various psychiatric disorders and neuropsychiatric symptoms. However, whether combining rTMS and tDCS can safely and effectively treat psychiatric conditions remains unknown. In this systematic review, we seek to summarize all existing studies that have combined rTMS and tDCS to remedy psychiatric disorders and symptoms.

METHODS

We searched four databases in addition to grey literature to identify relevant studies. All abstracts and manuscripts were independently reviewed by two reviewers. For inclusion, studies necessarily consisted of those who received both rTMS and tDCS for a psychiatric condition or symptom.

RESULTS

Fourteen studies were reviewed, which had relevance to unipolar depression (five), bipolar disorder (two), obsessive-compulsive disorder (two), Alzheimer's Disease (one), chronic insomnia (two), depressive and anxiety symptoms (one) and stress (one). In three RCTs on unipolar depression, the group receiving both rTMS and tDCS experienced significant reductions in mean Hamilton Depression Rating Scale (HDRS) scores (by 18.22, 16.59 and 20.04) as well as response rates (83.33 % and 91.7 %) and remission rates (83.3 %) - all of which were generally superior compared to treatment with rTMS or tDCS alone. For chronic insomnia, one RCT noted greater improvements in sleep quality/efficiency and depressive symptoms compared to monotherapy. The type and frequency of side effects were comparable to monotherapy, and no significant adverse events were reported.

CONCLUSION

The existing evidence suggests that combining rTMS and tDCS alone yields greater symptomatic benefit for unipolar depression compared to either treatment alone. Further studies involving additional protocols and disorders could elucidate the utility of combined treatment.