In 2012, the U.S. Federal Drug Administration concluded:^13
a. “Depression. In our literature search, we identified 12 papers that examined the
effect of CES on measures of depression (6 RCTs and 6 observational studies). In
most RCTs, depression levels did not differ significantly between patients who
were treated with active CES compared to those treated with placebo. However,
one randomized trial by Hearst et al. reported fewer depression symptoms in the
active CES treatment versus placebo groups. Of the six observational studies that
were reviewed, four studies reported improvement in depression symptoms after
treatment with CES. Moore et al. also reported improvement in depression post-
(versus pre-) CES treatment, but the findings were not statistically significant. The
observational study by Marshall et al. reported no difference in depressive
symptoms between the CES and placebo arms.
b. “Anxiety. There were 24 studies that investigated the impact of CES on anxiety
(11 RCTs, 11 observational studies, 1 meta-analysis, and 1 systematic review). Of
the RCTs that were evaluated, some trials reported a statistically significant
benefit of CES treatment versus placebo in reducing anxiety symptoms, while
other studies demonstrated no difference in anxiety between the groups.
Feighner et al. also conducted an RCT and reported a reduction in anxiety at 15
days post CES, but this effect was no longer significant at 26 days. The majority of
observational studies reported a positive association between CES treatment and
reduction in anxiety symptoms. In the single-arm observational study by
Bystritsky et al., improvements were reported for some but not all measures of
anxiety. Only 2 observational studies reported that CES did not have a significant
impact on anxiety based on clinical assessment and standard inventories. A meta-
analysis of 8 RCTs evaluating the efficacy of cranial stimulation on anxiety
indicated that CES versus sham treatment was associated with significantly
improved anxiety. Similar findings were reported in a systematic review that
examined 34 controlled trials involving a total of 767 patients receiving CES and