Benefits of transcranial Direct Current Stimulation (tDCS) on your Brain Health

In the 1900s, neuroscientists began developing techniques of electrical medicine to treat brain illnesses. For the most part of the last century, the main focus of research in Low-intensity-transcranial Electrical stimulations has been neuropsychiatric disorders. 

With advancements in electrical medicine, researchers have developed electronic devices that emit complex waveforms from weak electrical currents that have proven therapeutic. 

What does tDCS do?

Transcranial direct current stimulation (tDCS) has emerged as a technique used to stimulate the desired regions of the brain cortex and modulate its activity. It is a promising tool for upregulating or downregulating the cognitive and motor activities of the brain in conditions where these functions are severely affected, such as Depression. 

The most significant advantages of tDCS over other deep brain stimulation methods are its efficacy and ease of administration. While electroconvulsive therapy requires inpatient settings, i.e., inside the walls of a clinic or hospital, tDCS can be carried out in outpatient settings as well under the supervision of authorized personnel.

How does tDCS work?

tDCS is a non-invasive method of altering the excitability of the brain. It works by directly stimulating the pathophysiological areas of the cortex by strategically placing rubber-padded electrodes on your scalp. 

Weak electrical currents ranging from 0.2 mA to 4.0 mA (Most of the time 1-2 mA are clinically used) are applied for 10–20 minutes in the form of complex waveforms to either increase or decrease the activity of neurons directly under the electrodes. 

It is currently under investigation how many sessions of tDCS are needed, as there are no specific guidelines. tDCS works through two mechanisms:

1. Immediate Effect: Change in Polarity of Neurons

In an applied electric field, the redistribution of charges occurs across the cell membrane. This modulates the ability of neurons to be hyperpolarized or depolarized, which changes the ease with which a neuron can fire an impulse.

2. Late Effect: Neuroplasticity and Neurochemical Modulation

Experiments have shown a change in neuronal orientation and neuronal morphology. This effect implies that neural connections called synapses are more easily moldable and flexible, hence “Plastic.” This effect is also seen in the mechanism of action of anti-depressants such as SSRIs. 

Studies have also revealed changes in levels of neurotransmitters like GABA and brain-derived neurotrophic factors (BDNF) and cell receptors like glutamate receptors, NMDA, and AMPA.

Why Choose tDCS Over Medications? 

There are two major reasons:

• tDCS is supported by clinical evidence
• It is a cost-effective treatment

1- Evidence-Based Therapeutic Role of tDCS

Many studies showcase the therapeutic effects of Non-invasive Brain Stimulation (NIBS) in treating neuropsychiatric pathologies and improving sensory and motor functions. 

Evidence also supports the augmentation of tDCS with other forms of intervention, such as physiotherapy and cognitive therapy. 

1. Depression 

A study was done in 2013, which revealed that tDCS has comparable benefits to using sertraline antidepressants when used alone. However, the combined effect of tDCS and sertraline had increased efficacy compared to when administered alone. 

Another study deduced that Cranial Electrotherapy Stimulation (CES) is more efficacious than antidepressants such as Prozac, Zoloft, Effexor, and others.

2. Schizophrenia

Use of tDCS at 2 mA for 20 minutes on 5 consecutive days has reported a decrease in auditory hallucinations, which are positive symptoms in schizophrenia. Another case study shows decreased negative symptoms such as anhedonia, avolition, and blunted facial and vocal expressions. There is increasing evidence of improved cognition in schizophrenia, especially in working memory and attention.

3. Stroke

 A recent study was done on patients who recently had a stroke, in which a combination of tDCS and physiotherapy was administered. 50 patients received 20 sessions of tDCS in the first month. Researchers noticed significant improvements in muscle strength, dexterity, sensitivity, anxiety, and depression by the end of 1 year after the patients had an acute stroke. 

Another study supports a combination of tDCS with intensive occupational therapy and peripheral neuromuscular electrical stimulation in pediatric patients with chronic stroke. 

4. Parkinson’s Disease  

A review study on the augmentation of tDCS with physical and cognitive training in Parkinson’s disease revealed consistent positive results in the improvement of upper limb motor function and cognitive function. Furthermore, a few studies also suggest better gait and postural control.

5. Opioid Use Disorder

There is increasing evidence supporting Non-invasive Brain Stimulation (NIBS) approaches to reduce opioid exposure in cases of pain disorders. A review study suggested that tDCS as an adjunct with Medication-Assisted Treatment (MAT) and psychotherapy will reduce relapses of opioid use disorder and the associated risks of MAT. 

2- Cost Effectiveness

The initial cost of tDCS by devices such as AVE is greater. However, it breaks even after the first few months while the medications will still cost the same, but AVE will not. The following graph showcases how tDCS amounts to substantial cumulative savings by the end of 12 months.

Is tDCS safe to administer?

There are no significant health risks associated with tDCS. It is a safe technique with very mild adverse effects, including itching, headaches, and irritation on the application sites. 

The British National Institute for Health and Care Excellence (NICE) states that tDCS raises no significant concerns. However, NICE also recommends that it be done only under 

• special arrangements 
• clinical supervision of a specialist 
• proper consent. 

What does the future hold for tDCS?

tDCS has proven to be a major game changer in electrical medicine. It has all the potential to prove a coming-of-age therapeutic method. However, its efficacy can be further improved by personalizing the technique, considering the population's functional and anatomical variability.