While depression is relatively common in pregnancy and we have data to support the reproductive safety of many different antidepressants, many women are reluctant to use antidepressant medications during pregnancy. Because untreated depression in the mother has been associated with worse pregnancy outcomes and may have long term effects on the child, there is a clear need for effective and safe strategies for the treatment of depression during pregnancy.
Transcranial direct current stimulation (tDCS) is a non-pharmacologic, non-invasive treatment for major depression. In this intervention, the dorsolateral prefrontal cortex, a region of the brain that functions abnormally in depressed individuals, is directly stimulated with low intensity current (0.5 –2 mAmps). Typical side effects are mild and include transient headache, unusual skin sensations or itching at the site of the electrode. Most importantly, the effects of tDCS are limited to the brain. Thus tDCS would be a particularly attractive treatment for women with depression during pregnancy. In a pilot randomized controlled trial, Vigod and colleagues present the results of 16 women with antenatal depression treated with tDCS.
In this study, pregnant women (14 – 32 weeks of gestation) with major depressive disorder who had declined treatment with antidepressant medication were offered treatment with tDCS. Participants (n=20) were randomly assigned to tDCS or a sham control. Active tDCS cosisisted of 30-minute sessions of 2 mAmp direct current applied over the dorsolateral prefrontal cortex, five days per week, for a total of 3 weeks. Sham treatment was administered similarly, but with the current turned off after 30 seconds. Depressive symptoms were measured using the Montgomery-Asberg Depression Rating Scale (MADRS) post-treatment and again at 4 and 12 weeks postpartum.
Of the 20 women randomized, 16 completed treatment and provided analyzable data (124 tDCS and 122 sham sessions). At baseline depressive symptoms.were in the moderate range in both groups based on average MADRS scores. At the termination of treatment, MADRS score in the tDCS group dropped from 23.5 (SD 5.15) to 11.4 (SD 7.11) and from 26.8 (SD7.48) to 15.8 (SD 7.65) in the sham control group. Maternal heart rate and blood pressure and fetal monitoring were all within normal limits in both groups. No serious pregnancy complications were observed in either group.
At 4 weeks postpartum, 75.0% (6 out of 8) of the women who had received tDCS were remitted versus 12.5% (1/8) of the women in the sham control group (p = 0.04). At 12 weeks postpartum, remission rates were 75.0% in the tDCS group and 25.0% in the sham bourp. Two participants in the tDCS group and three sham-control started antidepressants by 12 weeks postpartum.
The Bottom Line
It is difficult to see the difference between tDCS and sham treatment at the termination of treatment. In previous treatment studies of pregnant and postpartum women, we have often seen high rates of placebo response, especially when treatment requires frequent contact with clinicians and the research staff. One might imagine that with tDCS (or sham treatment) delivered daily over a course of three weeks, there might be even higher rates of placebo response.
Nonetheless, the beneficial effects of tDCS are clear when we look at the prevalence of depressive symptoms during the postpartum period. Women who experience depressive symptoms during pregnancy are at high risk for postpartum depressive symptoms; thus, we would anticipate high rates of PPD in the participants of this study, but we see a clear difference between the two groups. At four weeks postpartum, 25% of the women in the tDCS group are depressed compared to 87% of the women in the sham group. At 12 weeks, the prevalence of depression is 25% for tDCS and 75% for sham. This is a relatively small study, yet the findings are fairly striking. This study suggests that tDCS administered during pregnancy leads to reductions in depressive symptoms and simultaneously reduces risk for postpartum depression.
Unfortunately at this time, tDCS has not yet been approved for the treatment of depression by the FDA; thus, it is considered an experimental procedure and is not typically covered by health insurance. That said, there has been considerable interest in the use of brain stimulation to treat depression, incudinging repetitive transcranial magnetic stimulation (rTMS), which was recently approved by the FDA for the treatment of depression. In comparison to rTMS, tDCS has some advantages in that it is less costly, easier to handle, more portable, and less likely to cause serious adverse events (e.g., seizure).
Dr. Vigod and colleagues at Women’s College Hospital in Toronto, Ontario will be recruiting for a larger clinical trial with tDCS for women with depression during pregnancy. Because tDCS equipment is portable, women participating in this trial will be trained in its use and will be able to self-administer treatment at home. Given that lack of convenience is commonly reported as a barrier to pregnant and postpartum women’s participation in research studies (and, in addition, a reason for this population to decline more time-intensive forms of treatment), Dr. Vigod notes that offering a take-home tDCS intervention to women where they receive their obstetric care would improve study recruitment and may ultimately facilitate access to much-needed care.
Ruta Nonacs, MD PhD
Kurzeck AK, Kirsch B, Weidinger E, Padberg F, Palm U. Transcranial Direct Current Stimulation (tDCS) for Depression during Pregnancy: Scientific Evidence and What Is Being Said in the Media-A Systematic Review. Brain Sci. 2018 Aug 14;8(8) Free Article
Vigod SN, Murphy KE, Dennis CL, Oberlander TF, Ray JG, Daskalakis ZJ, Blumberger DM. Transcranial direct current stimulation (tDCS) for depression in pregnancy: A pilot randomized controlled trial. Brain Stimul. 2019 Nov-Dec;12(6):1475-1483.