Nov. 15, 2024 -- Have you heard about transcranial direct current stimulation devices? They’re among the latest group of consumer health technology products causing excitement. These devices consist of headgear and sponge electrodes that deliver painless electrical currents to the outer level of the brain (cortex) to treat depression, anxiety, and posttraumatic stress disorder in some patients.
As interest in the devices, known as tDCS, has grown, do-it-yourselfers have quickly learned to hack the science and create homemade devices, sometimes using nothing more sophisticated than headbands, sponges, and a 9-volt battery. It’s easy to find DIY discussions and sales in Reddit forums. College students are reportedly trading in Adderall for tDCS to improve focus during exams. And the tDCS device popularity has become so great that they actually boast their own category on Amazon Marketplace.
“I don’t think that the devices you can buy online are ready for clinical use,” said Leigh E. Charvet, PhD, a clinical neuropsychologist, professor in neurology, and director of the tDCS Program at NYU-Langone Health in New York City. Charvet points to the example of current strength, which in the research setting is calibrated to deliver a moderately intense current. “Anybody can make a tDCS device, but you don’t know what you're getting, especially in terms of the current,” she said.
Another question concerns the problem or condition you are trying to address, especially if it’s mood-related.
“If you have mood symptoms, you should have a diagnosis. There are conditions that cause depressive symptoms, like hypothyroidism or some sort of inflammatory response in the brain. You need to know what you are treating before you start,” said Joan Camprodon, MD, PhD, chief of the Division of Neuropsychiatry at Massachusetts General Hospital in Boston and an associate professor of psychiatry at Harvard Medical School.
This means buyers might wish to hold off; easy retail or homemade access does not equal effectiveness. What’s more, tDCS is not FDA-approved for any use in the U.S.
tDCS: The Basics
For more than two decades, researchers have studied how and if tDCS might offer an alternative to traditional treatments for a variety of brain conditions, especially major depression.
“The advantage of doing this with devices is that the brain is an electric organ, so they allow us to ‘talk directly’ in the brain’s language,” explained Camprodon.
Camprodon said that tDCS changes brain neurons’ electrical properties as well as brain activity in a way that affects behavior. Though medical-grade devices may look similar to those on the consumer marketplace, they deliver a prescribed, pre-set, low-grade electric current, ideally while the user also engages in other activities such as speech and training or mindfulness exercises such as meditation. Each session lasts anywhere from 20 to 30 minutes, and consistency is key. These devices have been designed for ease of use and portability, but control ultimately lies in the hands of the doctor.
Charvet, who mentioned that her team has conducted roughly 28,000 home-based sessions in 14 clinical trials, said that home-based tDCS research has become the norm. Otherwise, patients would have to come into the clinic daily, which creates resource, time, and access challenges.
However, the home element is only one factor.
“The clinical model for tDCS is the same one you would have before any treatment starts,” said Camprodon.
"Patients need to be evaluated by a doctor and provided with a diagnosis and a plan that may include medication and tDCS or tDCS alone. The device is then pre-programmed to deliver the exact dose of current for a specific amount of time; it then turns off and it can’t be used again until the next day,” he explained.
The learning curve for patients using tDCS devices is small. By and large, most studies have involved sending a customized device to the patient’s home, meeting for a virtual show-and-tell so patients can learn appropriate placement and usage, and reviewing the treatment plan, including when to use the device and for how long.
These devices are not intended to be one-offs or used intermittently; the effect is cumulative.
“Although most clinical trials have been 10 sessions or less, we believe that you need at least 20 sessions, five days a week over four weeks,” said Charvet. After that, the patient is reevaluated to see if more treatment is needed or if it should be changed.
Camprodon added that ideally, “you’d do a course of treatment, induce changes (including permanent ones) that outlast the time of the stimulation, and then stop. Once you’re out of the depression, we might do milder, less frequent maintenance treatment, but we don’t really know the specifics yet.”
Is Safety a Concern?
Overall, clinical studies and anecdotal evidence have shown the devices pose few safety concerns, although long-term outcomes are still unclear.
A recent study that compared active tDCS devices to inactive devices in people with depression found that most common side effects include a light tingling feeling, the occasional electrical burn (likely due to insufficiently moistened sponges), skin redness, irritation, and dry skin.
“We offered a 24-hour phone number that people could call at any time,” said Cynthia Fu, professor of psychotherapy at King's College-London and one of the study co-authors.
But Fu emphasized that as far as safety goes, she is mostly concerned about who is using them, for what purpose, and if use is consistent.
“Some people stop using them and we need to know why,” she said, explaining it could be side effects or something else. She also pointed to the danger of unsupervised use in someone who has not had a full clinical workup and diagnosis, echoing Camprodon’s point about the need to understand if depression occurs on its own or as a result of another condition.
“We also want to know if there’s a change in their status; they should have a clinical connection and not try to treat themselves,” added Charvet. This speaks to the need for a therapy component when using tDCS. “It’s the difference between practicing cognitive behavioral therapy on an app versus having a therapist,” said Charvet. “I believe that a live connection with somebody, especially in the case of depression, is really helpful for recovery.”
Ready for Primetime or Not?
For now, tDCS should only be considered within the framework of a clinical trial, and most people being assessed have first-time depression or the type that resolves temporarily or returns.
But these experts cautioned against using DIY and retail tDCS devices. Factors like quality assurances of safety and accuracy; accurate, stable, and constant current delivery; the ability to sense resistance as the skin builds tolerability to the sensation and adjust the current accordingly; capability to adjust dosage and timing; and indicators when batteries need to be replaced are important. A quality device also ramps up and down the current over a 15-20 second time period to allow the body to adjust and avoid lightheadedness. And the sponge electrodes need to be adequately covered to prevent burns.
Better safe than be sorry; at least for now.
