Transcranial Direct Current Stimulation Reduces Depression Following Strokes
One-third of people who have strokes face depression afterward. New research is looking to expand the safe options for the treatment of depression following strokes. At the 2015 meeting of the Society of Biological Psychiatry, researchers led by Leandro Valiengo presented their successful randomized, sham-controlled double-blind study of transcranial direct current stimulation for post-stroke depression. Forty-eight people who had depression following a stroke were randomized to receive either a sham procedure or tDCS in twelve 30-minute sessions over a period of six weeks. After the six weeks, those who received tDCS had fewer symptoms of depression, more remission, and better response. There were no serious side effects.
TDCS is very low-level electrical current that has a positive (anode) or negative (cathode) electrode. Anodal stimulation of the cortex is usually associated with positive effects on mood and cognition. TDCS sessions in this study consisted of 2-mA anodal left/cathodal right dorsolateral prefrontal stimulation.
Editor’s Note: Placebo-controlled studies have repeatedly indicated that patients who have a stroke show better neurological and psychiatric response afterward when they are given an selective serotonin reuptake inhibitor (SSRI) antidepressant, whether or not they have depression or a prior history of depression. If a neurologist does not suggest treatment with an SSRI after a stroke, ask why not. Since antidepressants increase brain levels of brain-derived neurotrophic factor (BDNF) and increase neurogenesis, they could help with post-stroke recovery.
Transcranial Direct Current Stimulation May Improve Cognition in Schizophrenia
A recent study by Robert Smith and colleagues studied the use of transcranial direct current stimulation (tDCS) in patients with schizophrenia. TDCS is very low level current that has a positive (anode) or negative (cathode) electrode. Anodal stimulation of the cortex is usually associated with positive effects on mood and cognition. Patients received either five sessions of active tDCS for 20 minutes (at 2 milli Amps) or a sham stimulation for the same period. Then, one day after the final session, the patients were measured on a variety of scales for cognition and illness. Patients who received the active tDCS showed more improvements in working memory and attention than patients who received the sham treatment.
There was no difference in the two groups’ schizophrenic symptoms, including hallucinations. Smith and colleagues suggest that the improvements in cognition may result from changes to brain connectivity networks, since abnormalities in these networks have been identified in patients with schizophrenia and bipolar disorder.
Replications of this type of study are needed to clarify the effect of tDCS on cognition in schizophrenia, but given the safety and convenience of the procedure, the findings are promising.
TDCS Promising for a Range of Illnesses
Transcranial direct current stimulation (tDCS) shows promise for a range of problems. In new research presented at the 2014 meeting of the Society of Biological Psychiatry, it was reported to be effective for improving cognition in bipolar disorder, alleviating depression, and reducing hallucinations.
How TDCS Works
At the meeting, researcher Marom Bikson discussed tDCS technology. The treatment can be delivered with a 12-volt battery. The anode directs current inward and is excitatory, while the cathode directs current outward and is inhibitory. The dendrites at the top of neurons under the anode are hyperpolarized by the tDCS, leading to relative depolarization of the cell soma, thus increasing excitation. TDCS, unlike repetitive transcranial magnetic stimulation (rTMS), which causes cells to fire, is only neuromodulatory, inducing minor changes in membrane polarization.
TDCS Improved Cognition in Bipolar Disorder
At the 2014 meeting of the American Psychiatric Association, Roberto Delle Chiaie et al. reported that two mA tDCS for 20 minutes for 15 days (anode over the left prefrontal cortex and cathode over the right cerebellum) improved immediate and delayed recall, trail making with a pointer, and motor coordination in 17 euthymic bipolar patients. This very promising result deserves further study and replication.
Antidepressant Effects of TDCS
At the 2014 meeting of the Society of Biological Psychiatry, Collen Loo reported that tDCS had positive effects in depressed patients compared to sham treatment. This complements a 2013 article by Brunoni et al. in JAMA Psychiatry that tDCS plus the selective serotonin reuptake inhibitor (SSRI) antidepressant sertraline (Zoloft) was more effective than either treatment alone.
TDCS for Treatment-Resistant Hallucinations
Jerome Brunelin et al. reported at the meeting that tDCS had positive effects in patients with schizophrenia who had hallucinations that resisted treatment. The positive electrode (anode) was placed over the left prefrontal cortex and the negative electrode (cathode) over the left temperoparietal area, where hallucinations are thought to originate. Stimulation was at two mA for 20 minutes, five days per week for two weeks. Effects lasted as long as 30 days and were associated with reduced functional connectivity of these brain regions.
Low frequency (1Hz) rTMS, which decreases neural activity, also improves refractory hallucinations when applied over the temperoparietal area, which is important for language. Placing the cathode over this area in tDCS is also inhibitory, so comparisons of rTMS with tDCS for suppressing hallucinations would be of great interest and importance.
Transcranial Direct Current Stimulation Plus Zoloft Has Better Antidepressant Effects Than Either Treatment Alone
Transcranial direct current stimulation (tDCS), in which a barely perceptible level of electrical current is applied directly from one side of a patient’s scalp to the other, is a promising treatment for patients with tought-to-treat depression. A 2013 study by Brunoni et al. in JAMA Psychiatry examined whether combined treatment using tDCS and the selective-serotonin reuptake inhibitor (SSRI) antidepressant sertraline (Zoloft) would be a safe and effective treatment for unipolar depression. The combination was better than either treatment alone and better than placebo.
The six-week study used what is called a 2×2 factorial design, in which 120 patients with unipolar depression received either 50 mg/day of sertraline or placebo and also received either real tDCS or a sham procedure. The tDCS was administered in twelve 30-minute sessions, one per day Monday through Friday during the first two weeks, followed by one every other week. TDCS consists of an anodal (positive) and cathodal (negative) current placed at particular positions on the head. This study used 2 microamps of anodal left/cathodal right prefrontal stimulation for the tDCS treatment.
While the combination of sertraline and tDCS was significantly better than all three other treatment options (sertraline plus sham procedure, placebo plus tDCS, and placebo plus sham procedure), sertraline by itself and tDCS by itself resulted in similar efficacies. However, TDCS by itself was also significantly better than placebo, while sertraline by itself was not.
Side effects among the different treatment options were similar, except those who received tDCS had more scalp redness. There were seven instances of patients developing mania or hypomania during the study, five of which occurred in the combined tDCS and sertraline treatment group, higher than the 1–2% rate that would be expected in a study of unipolar depression.
