Transcranial Alternating Current Stimulation (tACS) for long COVID
Last updated on August 13, 2024, 09:07 am
TRANSCRANIAL ALTERNATING CURRENT STIMULATION
What is tACS?
Transcranial Alternating Current Stimulation, or tACS, is a non-invasive brain stimulation that delivers rapidly alternating electrical currents to the scalp through electrodes. Rather than providing a constant electrical current like in transcranial direct current stimulation (tDCS), the current supplied in tACS oscillates in a waveform to stimulate the natural rhythmic pattern of electrical activity in the brain. These oscillating currents are believed to interact with ongoing oscillations in our brain that occur when we perform cognitive tasks. The current can be applied in various frequencies to target various effects. tACS is not a new technology and has been used for decades in cognitive neuroscience and various psychiatric and neuropsychiatric disorders such as poststroke depression, Parkinson’s disease, schizophrenia, and MS.1,2
How can tACS help alleviate certain long COVID symptoms?
Many long COVID patients have reported cognitive symptoms of fatigue and brain fog that can impact activities of daily living. The mechanism behind this is not fully understood but is believed to be due to a dysregulated immune system that causes ongoing damage to the brain.
An acute COVID infection can cause an overreactive immune response called systemic inflammatory response syndrome or SIRS. Inflammatory mediators are excessively released at this time, which can cause fatigue. The body tries to create a compensatory response, which can lead to more dysregulation and persistent inflammation. Inflammation can also cause reduced blood flow throughout the brain, which can also cause fatigue.1 In moments of fatigue, it is hypothesized that the brain creates abnormal oscillations that tACS can modulate to help improve symptoms.3
What evidence supports the use of tACS for long COVID?
More studies are currently needed to investigate the use of tACS for long-COVID fatigue. Still, it is a feasible non-pharmacological option for reducing post-COVID fatigue and improving cognitive symptoms. tACS has been used in Alzheimer’s disease and was found to improve cognitive performance after one-hour-long daily stimulations over a two to four-week period.1 tACS has also been found to enhance attention task performance in a sham-controlled experiment.4 However, one study investigating the use of tACS on fatigue resistance in young adults found that tACS did not increase the fatigue resistance in a precision grip task requiring muscle contractions of the hand.5 These studies may suggest that tACS has limited effects on muscle fatigue but potentially more beneficial effects on cognitive fatigue. More studies are needed to determine the benefit of tACS in fatigue, specifically for long-COVID induced fatigue.
What are some things to watch out for with tACS?
tACS is a safe and well-tolerated procedure that can be done for multiple sessions. Some side effects during the procedure may include flashes of light while your eyes are closed (also known as phosphenes), dizziness, and skin or pressure sensations. All reported side effects are temporary, and no serious adverse effects have been reported, even at higher frequencies.6
References:
![](https://staging.compendirx.com/wp-content/themes/medical-directory-child/assets/img/insta.png")
