Electroshock therapy, often regarded as an artifact from a nightmarish time when lobotomies were commonplace, is coming back into popularity in the form of transcranial direct current stimulation (tDCS). No longer used to subdue unruly Jack Nicholson like patients, tDCS is showing promise as a treatment for depression. Those who have experienced the disorder, or knows someone who has, knows the symptoms of depression can be so bad that a patient is willing to try anything for relief, including passing an electric current through their brain.
Depression itself is an umbrella term for several different mood disorders, ranging from major to minor depression. The symptoms of depression include feeling empty or hopeless, feeling guilty and worthless. Activities that were enjoyable are no longer so, and concentration and memory suffer. At it's most dangerous depression can lead to suicide (Depression, 2011). Because the causes of depression are difficult to determine, treatment can be complex. Depression can be caused by a combination of genetic, biological, environmental, and psychological factors, and so it is incredibly difficult to determine the precise cause and correct it. Currently, one of the most popular theories is that neurotransmitters, the chemicals in your brain that can affect your mood, are imbalanced in the brains of depressed individuals (Depression, 2011). However, proving this theory is difficult. While it is possible to test neurotransmitters using tests such as functional MRIs, such tests are expensive and are not commonly used to diagnose depression (Scanning the Brain, 2006).
Depression and other disorders that damage cognition can damage the brain's neuroplasticity, preventing it from storing information properly (Hallerstein, 2011). Neoroplasticity is defined by the brains ability to alter neural networks (Neuroplasticity, 2013). The inability of the brain to change its neural pathways in the face of new information can leave people in states of chronic stress. For example, after trauma, a damaged brains inability to alter its neural pathways can leave a person feeling anxious or frightened all the time, seriously damaging their quality of life (Hallerstein, 2011).
Medical treatment for depression often involves various types of antidepressants. Some of the most common anti-depressants target neurotrasmitters, preventing the reuptake of chemicals such as dopamine, thereby increasing the amount of dopamine (a “happy” neurotrasmitter) in the brain (Depression, 2011). As with most medications, antidepressants can have severe side effects. For example, a very common side effect is sexual dysfunction that can continue even after a person stops taking the medication (Depression, 2011). Talk therapy is another common treatment for depression, often used in conjunction with medication. During sessions with a therapist, patients learn how to restructure their own thought patterns into a more positive light (Depression, 2011).
Sometimes, the previously listed treatments are not enough. But what options are left for a person who is still depressed after a combination of medication and therapy? Transcranial direct current stimulation may offer hope. Posited to be effective in treatment not only for depression, but migraines, fibromyalgia, and epilepsy, tDCS is also said to improve memory and cognitive function (Brain Stimulation Clinic, 2011). A relatively simple procedure, tDCS involves placing electrodes on the scalp with an elastic headband (over the targeted area of the brain) while the patient is lying on their back. A weak and painless electric current is passed through the brain (Brain Stimulation Clinic, 2011). tDCS can be time consuming, however, with treatment needing to extend up to 30 minutes, administered for approximately 8-10 session, though this can varies by individual and diagnosis (Nitsche et al 2008).
It is thought that the electric current increases cortical excitability, meaning that it increases the number of neurons that fire in the targeted area of the brain (Nitsche et al 2008). This is why it is theorized that tDCS increases neuroplasticity, which is why it is able to boost memory and cognition (Wood, 2012). Stimulating the stunted areas of the brain, the ones that cause constant anxiety or fear, gives the neurons the kick they need to start correcting these pathways.
Patients often stop taking medication due to the dramatic and disruptive side effects. Does tDSC have similarly bad side effects? Currently, the most common side effects recorded are mild headache and itching or redness of skin where the electrodes are attached (Arul-Anandam, et al. 2009). Because tDCS involves passing an electric current through the brain, seizure is a common concern, but there is no record of seizure occurring in patients who have received this treatment (Arul-Anandam, et al. 2009).
There have been several studies on tDCS, some on animals, some on people. The studies have looked at the effects of brain activity (using MRIs and other brain imaging technology) as well as testing for effects on memory and comparison betweens tDCS and placebo treatments. For example, one double blind study found that those who had received the treatment retained the positive effects of tDCS one month past treatment (Boggio et al, 2008). However, this study had a relatively small sample size of 40 patients who suffered from major depression. Similarly, another study that found similar results only had a sample size of ten patients with major depression (Fregni et al, 2006). While the studies show promising results, these results must be taken with a grain of salt until they are replicated in a much larger and more representative sample.
Few studies look at the long-term effects of this treatment on depression (most stop after a few weeks or months), there is evidence that the increase in cognition is long-term effect of tDCS (Wood, 2012). Hopefully, further studies will show a similar long-term effect on mood disorders.
Transcrianial direct current stimulation is also showing promise in a particular subset of people who commonly suffer from Major Depressive Disorder: HIV patients (Knotkova et al, 2012). HIV patients have high rates of comorbidity with major depression. Treating HIV patients with depression can have seriously social health consequences. Because depression is correlated with uncompleted antiretroviral treatments, it can increase the likelihood that HIV is passed onto a partner. Depression also increased the progression of HIV, seriously hindering the quality of life of those who suffer from both disorders (Knotkova et al, 2012).
A groundbreaking study on the effects of tDSC in HIV patents with Major Depressive Disorder found that those who completed the treatment had an increase in mood that lasted for at least two weeks (Knotkova et al, 2012). The study also found that tDSC was relatively safe for those with HIV patients, though they did record clinically significant (though not dangerous) changes in blood pressure and heart rate (Knotkova et al, 2012). The study suffers from the same flaws of many others, however, including a lack of long-term evaluation and a limited sample size. The researchers only included a single follow up exam two weeks after treatment had concluded. The study itself consisted of a sample size of ten people (five women, five men), two of whom were unable to fully complete the treatment (Knotkova et al, 2012). While the results were promising, there needs to me much more studied in regards to the effectiveness of tDCS.
If the preliminary studies are accurate, transcranial direct current stimulation is showing promise as a treatment for not only pain management and memory problems, but also different levels of depression. However, the use of this treatment for depression is still in its infancy, with no large term studies currently available. As of 2006, the United States National Institute of Health was looking for patients 18-65 with depression to volunteer as tests subjects for a clinical trial on tDCS. However, the study is still listed as “recruiting participants” (University of New South Wales, 2006) and it is unclear when, if ever, the study will be done. Another study by the University of Oklahoma and department of Veteran Affairs is also is set to be completed in September 2014. However, this study is only looking at whether or not tDCS has any kind of effect on motor function recovery in hands and arms (University of Oklahoma, 2012). While the study will yield more insight into how tDCS affects the brain, it will not necessarily provide helpful information for those suffering from depression.
Clearly, more research is needed in regards to the effects of tDCS on depression. Regardless of the lack of large-scale clinical trails available, at least one clinic is open that offers tDCS. The Brain Stimulation Clinic in Atlanta, Georgia, offers tDCS for a wide variety of problems, including depression. Those suffering from depression in Georgia are currently offered the choice of this treatment if they so wish. While the clinic recognizes the limits of the studies, it also recognizes the potential for this treatment. Perhaps, in future years, it trasncrianial direct current stimulation will become a commonplace and hopeful treatment for those who need it most.
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