Published 5:15 pm, Tuesday, October 30, 2012
San Francisco Chronicle
Applying a current of electricity through the brain conjures up the kind of nightmare-inducing seizures immortalized in the 1975 film adaption of Ken Kesey's "One Flew Over the Cuckoo's Nest."
But a kinder, gentler, almost imperceptible form of electric brain stimulation - an experimental approach known as transcranial direct current stimulation - is gaining traction as a promising therapy for brain injuries due to stroke or other traumas, depression, dementia, attention-deficit disorder and other conditions.
Transcranial direct current stimulation, or tDCS, bears little in common with electroshock therapy or invasive forms of deep brain stimulation, which involve drilling holes in the head and implanting electrodes.
The level of the current used is tiny - typically between 1 and 2 milliamps, or less than one-one-hundredth of a single electrical watt. At most, the current causes a tingling or slight itching, if it's felt at all.
Even the technique's staunchest defenders acknowledge that the idea of treating a broad range of disorders with something you can hardly feel and that has few, if any, side effects sounds more like snake oil than science.
"How could this do anything? It seems so small. We're talking about a few volts," said Marom Bikson, associate professor of biomedical engineering at City University of New York who co-founded Soterix Medical Inc., a company that holds patents to Bikson's transcranial direct current stimulation devices.
Jolt to the brain
But Bikson said studies have shown a few volts of current can change the rate at which a brain cell fires in a way that is believed to improve brain plasticity, or its ability to change and learn new things.
"It's not some magical, unknown hocus-pocus," he said.
The concept is fairly simple: After dampened electrodes are strapped to a patient's scalp, a device charged by a 9-volt battery - the kind used in transistor radios - delivers a small current to change the activity in targeted regions of the brain.
The current, which is typically delivered for 10 to 30 minutes over multiple sessions, is thought to be able to excite or inhibit the brain's neurons in the stimulated area.
A positive current could help people with depression, stroke or other brain traumas, while a negative current may be helpful for such conditions as epilepsy or language recovery. Both currents can be used at the same time, and the effects of the stimulation are thought to continue or even increase, even after the device has been turned off.
Transcranial direct current stimulation has been used in a small number of hospitals - mostly on the East Coast - since about 2000 but has not been approved by the U.S. Food and Drug Administration. Soterix and other manufacturers plan to seek FDA approval for the devices once enough research has been done.
Earlier this month, Bikson was part of a research team that demonstrated the technique for doctors, therapists and other health experts during a one-day workshop at Alameda County Medical Center's Highland Hospital in Oakland.
Getting the word out
Dr. Lance Stone, medical director of rehabilitation and restoration at the county's Fairmont Hospital in San Leandro, was introduced to the technique earlier this year and invited the researchers to give his colleagues and other specialists the opportunity to learn more about it.
Stone is interested in the device's use in the emerging field of neurorehabilitation, which teaches or retrains patients with nervous system injuries such as stroke, Parkinson's disease or other brain trauma.
"There seems to be countless potential applications (of the technique) for acquired neurological disorders, but the main ones seem to be primarily pain, motor recovery and depression," said Stone, who plans to apply for a research grant to study the device.
The concept of using electrical stimulation for health purposes dates back thousands of years to the Greeks, whose medical practitioners were said to use electric eels in water to reduce symptoms of arthritis and other types of pain.
Modern usage of electroconvulsive therapy, formerly known as electroshock therapy, has been controversial, dating back to its early use in the 1940s and '50s in psychiatric hospitals. While it has been making a bit of a lower-voltage comeback in patients with severe depression, the method is generally considered a last resort because of the risk of memory loss and other side effects.
Trials and studies
Transcranial direct current stimulation has been around for decades, but the technique earned interest in the 1990s and early 2000s after some European physicians published promising results of the work. Currently it's the subject of numerous ongoing clinical trials and studies in this country.
In 2010, a team of Oxford University scientists published a small study that showed tDCS improved math skills in the majority of participants.
That same year, researchers at Beth Israel Deaconess Medical Center in Boston published findings that showed that the motor skills of stroke patients treated with the device, along with physical and occupational therapy, improved threefold compared with those who received a placebo form of stimulation and the same amount of physical and occupational therapy.
But some health experts warned that the technique's safety and effectiveness are unknown and that larger, controlled human clinical trials are needed.
"Whenever you do something - whether it's swallowing a drug or applying current - there may be a downside," said Dr. Sidney Wolfe, director of Public Citizen's Health Research Group, a consumer and health advocacy lobbying organization.
Wolfe said the device sounds promising and is the subject of a myriad of clinical trials but shouldn't be approved until the larger, controlled studies are conducted. "The variety of medical problems for which they are trying this is enormous, and in most of the studies the number of patients is so small it's not statistically significant," he said.
Dr. Dylan Edwards, director of the Non-Invasive Brain Stimulation and Human Motor Control Laboratory at Burke Medical Research Institute in White Plains, N.Y., agreed that further research is needed to answer many of the unknown questions. His institute received a $3.5 million grant from the National Institutes of Healthto study the device's effectiveness in stroke patients.
"The brain is an electrical organ," said Edwards. "What we're trying to do is develop methods that interfere with brain activity in a targeted way and positively influence it."
Edwards said several companies in the United States and around the world are already making transcranial direct current stimulation devices and he expects more.
Part of the appeal of the device is that it is relatively low cost - retailing for about $800. In addition, it's portable, so it can be used in many different settings.
Using on patients
Some doctors and researchers who attended the recent workshop had no experience using the device, while others had already tried it on a few patients. The device, which is considered investigational by the U.S. Food and Drug Administration, can be used either as part of a clinical trial or by a medical doctor for specific cases.
UC Berkeley psychologist Ludovica Labruna has experimented with using the device for language acquisition - to see if subjects could learn languages more quickly after receiving tDCS sessions. But she said her results have been somewhat disappointing, and she's not sure if she's using the device correctly.
"TDCS looks so simple, but it's really not so simple to apply because there are so many variables," Labruna said. "You really need to be trained."
Similar concerns drew Emily Kappenman to the workshop.
Kappenman, a postdoctoral researcher at UC Davis' Center for the Mind and Brain, said she's interested in the device's potential for working with patients with anxiety. She said she's tried it to see whether it helps people become less distracted and anxious by moving their attention away from certain emotions.
"It's hard to tell if it's working yet or if we're using optimal levels," she said. "It's hard to know what's best."
Brain stimulation uses magnetic or electrical energy to improve brain function. Here are some of the techniques in use or being studied:
Electroconvulsive therapy (ECT): With ECT, an electric current passes briefly through the scalp to the brain, inducing a seizure. It's generally considered only for those with severe depression or other serious mental illnesses who do not respond to other treatments.
Transcranial magnetic stimulation (TMS): TMS uses wrapped coil wires to generate electric current throughout the scalp and can induce involuntary movements. Although it has a few potentially serious side effects, including seizures, the treatment received federal approval for patients with severe depression in 2008.
Transcranial direct current stimulation (tDCS): Weaker still than TMS, tDCS has not been approved, but researchers are studying its use to help patients with strokes and other brain injuries. It has also been considered for use in healthy subjects, with researchers testing everything from memory enhancement to improved golf swing.
Source: Chronicle research Victoria Colliver is a San Francisco Chronicle staff writer.