What’s the difference between Transcranial Direct Current Stimulation (tDCS) and Cranial Electrotherapy Stimulation (CES)?*
When we think about noninvasive forms of neuromodulation, two big players in the field that immediately pop into mind are transcranial direct current stimulation (tDCS) and cranial electrotherapy stimulation (CES). tDCS and CES are often confused with one another due to their similarities in application. While both are incredibly useful in their own rights, there are distinct differences in the mechanisms of action of both forms of stimulation and their respective target elements.
tDCS Overview and Waveform
tDCS is one of many forms of non-invasive neuromodulation. tDCS works by applying a low energy direct current (DC) waveform to a targeted region of the brain. This low energy current does not cause neurons to fire but rather effects the plasticity of the brain. In other words, tDCS does not directly cause neurons in the brain to fire, but rather manipulates the likelihood of the neuron to fire under certain circumstances. Depending on where the elctrodes are placed, research has shown that different effects can be obtained. This figure shows the standard direct current (DC) waveform used in tDCS. At th onset of a tDCS session, a well designed tDCS device will slowly ramp up the current to the target intensity. The tDCS device will then ensure a constant DC output for the duration of the session, followed by a gradual ramping down of the current to end the stimulation.
CES Overview and Waveform
Like tDCS, CES is a form of non-invasive neuromodulation. However, CES uses a very different waveform. In cranial electrotherpay stimulation, a low energy pulsed alternating current (AC) is applied to stimulate the cranial nerves in the forehead. CES is typically administered across the temples using sponge or hydrogel electrodes but can also be done via stimulation of the earlobes using earclip electrodes. CES is FDA cleared for the treatment of depression, anxiety, and insomnia. A standard CES waveform can be seen in the image.
Are tDCS or CES FDA Cleared?
tDCS is considered an investigational technology by the FDA, and as such, cannot be marketed for a medical indication. tDCS is being researched for ADHD, impulse control, addiction, chronic pain, depression, and insomnia. In studies, tDCS has also be used to improve attention, mathematical ability, learning, audio perception, and creativity. New studies are also constantly being conducted every day and subsequently new potential treatments targets are bound to be discovered regularly. In Europe, tDCS has received CE clearance for the treatment of depression and chronic pain such as migraine and fibromyalgia.
CES is currently FDA cleared, and is marketed to treat depression, anxiety, and insomnia. Doctors may also prescribe CES off-label to treat pain, addiction, improve focus, and other conditions. As CES is considered a Class III medicald device, authorization from a licensed healthcare practioner is required to purchase a device.
What works better, tDCS or CES?
tDCS is not FDA cleared and is labeled as an investigational technology. As such, there are no medical claims assocaited with tDCS in the US. In Europe, tDCS is CE cleared for the treatment of depression and chronic pain such as migraine or fibromyalgia. Even though tDCS is not cleared for a medical indiciation in the US, this technology is more popular then CES and new research is being conducted daily by leading universities and clinics around the world.
Unlike tDCS, CES is FDA cleared for the treatment of depression, anxiety and insomnia. This technology has been around for many years and is availble with a prescription or device authorization. Many physicians, primarily psychiatrists, will prescribe a CES device as drug free alternative for treating depression. CES is also commonly provided as a maintenance device to those who receive TMS treatment.
What are the side effects of tDCS and CES?
tDCS and CES are similar in that their safety is supported by medical literature. Both CES and tDCS studies have reported short term side effects limited to mild and reversible skin irritation when using standard protocols and guidelines.
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