tACS research is in its infancy. Only very recently, the first small clinical trials have been published in the scientific literature. More research is needed to gain a better understanding of the potential therapeutic effect of tACS for the treatment of psychiatric and neurological disorders. tACS is "investigational use only" and is not FDA cleared for any indication.
Major Depressive Disorder
A recent study by Alexander and colleagues (publication available for free here) showed that tACS alters alpha oscillations, a type of brain rhythm that has been implicated in major depressive disorder. The scientists compared tACS at two different stimulation frequencies (10Hz and 40Hz) with a placebo stimulation. The study did find a significant difference in the number of patients who responded in terms of improvement of the depression symptoms. 10Hz-tACS had the most responders. This was a double-blind placebo controlled study of a 5-day stimulation paradigm. However, the study was small and failed to reach statistical significance for the primary outcome (change in severity of depression symptoms one month after stimulation). More research is needed to understand if tACS can treat major depressive disorder.
Auditory Hallucinations in Schizophrenia
A recent study by Ahn and colleagues showed that tACS strengthens alpha brain rhythms in patients with schizophrenia. This was a double-blind placebo controlled study of a 5-day stimulation paradigm. The primary clinical outcome of the study was a change in auditory hallucinations. The study was too small to detect statistically significant changes in symptoms. However, the change in brain rhythms by tACS correlated with clinical improvement. The abstract of the publication that reports the changes in brain rhythms is available here. The abstract of the publication that describes the clinical results in details can be found here. More research is required to understand if tACS can treat auditory hallucinations in patients with schizophrenia. There is currently a follow-up study at UNC-Chapel Hill that recruits patients with schizophrenia who experience auditory hallucinations.
Please contact us with any information about tACS treatment clinical trials.