Brain Stimulation Therapy
Brain stimulation therapy is a category of procedures in which electrodes or magnets, usually placed on the scalp or inserted into the brain, are used to treat some neurological disorders or serious psychiatric disorders that do not respond successfully to commonly used therapies and medications. There are several types of brain stimulation therapy, including electroconvulsive therapy (ECT), vagus nerve stimulation (VNS), repetitive transcranial magnetic stimulation (TMS or rTMS), magnetic seizure therapy (MST), and deep brain stimulation (DBS).
- Electroconvulsive therapy (ECT), sometimes colloquially referred to as “electroshock therapy,” is a non-invasive procedure, conducted under anesthesia, in which electrodes placed on the patient’s scalp administer electrical currents to the brain. These currents trigger a very brief, controlled seizure, or an electrical disturbance in the brain, theorized to foster changes in the brain that lessen the severity of mental health symptoms.
- Vagus nerve stimulation (VNS) is a procedure in which a small device is implanted in the patient’s chest to electrically stimulate the vagus nerve, the longest nerve in the body and a key component of the nervous system. Electrical pulses sent through the vagus nerve to the brainstem are thought to calm the hypothalamic-pituitary axis (HPA), the overactivation of which is associated with stress and depression. Non-invasive TNS devices are currently under investigation.
- Repetitive transcranial magnetic stimulation (TMS or rTMS) is a non-invasive procedure in which an electromagnetic coil is placed on the patient’s scalp. This coil delivers repetitive magnetic pulses to areas of the brain associated with mood, triggering changes in the brain that may reduce symptoms of anxiety, OCD, depression, and other conditions.
- Magnetic seizure therapy (MST) is similar to TMS, in that it is a non-invasive procedure in which magnetic pulses are delivered to the brain via the patient’s scalp. However, MST operates at a significantly higher frequency than standard TMS; therefore, as in ECT, treatment aims to induce a controlled seizure in the brain and must be delivered under anesthesia.
- Deep brain stimulation (DBS) is a procedure in which electrodes are surgically implanted in the brain and connected to a small generator placed in the patient’s chest. These electrodes then send controlled electrical impulses to specific areas of the brain associated with disorders such as Parkinson’s disease, OCD, epilepsy, and major depression.
Of these, ECT is the oldest and perhaps best-known procedure. ECT was first used in the 1930s; today, ECT and TMS are considered the most widely used brain stimulation therapies. Other approaches are considerably newer and some do not yet have extensive research support or FDA approval for psychiatric treatment. However, some brain stimulation therapies, such as VNS, have been formally approved by the FDA to treat mental health conditions such as major depression. Brain stimulation therapies are closely related to and may overlap with brain computer interfaces (BCIs), neural devices that translate brain activity into external data or physical action. (To learn more about this technology, see Brain Computer Interface.)
In a psychiatric context, brain stimulation therapies are most often used to treat serious mental illnesses such as treatment-resistant depression (major depression that does not respond to psychotherapy or medication), bipolar disorder, OCD, or schizophrenia. Such therapies are also often used to treat neurological disorders such as epilepsy and Parkinson’s disease.
ECT is typically used to treat severe depression—particularly when the depression is so severe that the patient is actively suicidal or is no longer able to care for themselves. It is also used to treat depression accompanied by psychosis that does not respond to medication. It may also be used to treat bipolar disorder, schizophrenia, and catatonia. In some cases, it may be used to treat severe agitation or violent behavior in adults with dementia.
VNS was developed to treat epilepsy that has not responded to drugs; it may also be used to help a patient regain functionality after a stroke. In recent years, VNS has gained prominence (and FDA approval) as a treatment for severe, treatment-resistant depression. It is currently being studied as a potential treatment for bipolar disorder, Alzheimer’s disease, and physical conditions such as IBS or chronic headaches.
TMS/rTMS is FDA-approved to treat certain types of depression—generally, depression that hasn’t responded to standard treatments such as talk therapy or medication. It may also be used in conjunction with traditional treatments. Some research has found that TMS treatment may also lead to improved memory. (To learn more about when TMS is used, see Transcranial Magnetic Stimulation Therapy.)
MST is still in its research phase and has not been formally approved to treat any mental health condition. In the context of research studies, however, it is being investigated as a possible treatment for treatment-resistant depression, OCD, schizophrenia, bipolar disorder, and other psychiatric and neurological conditions, with some positive results thus far.
DBS is a procedure originally developed and FDA-approved to treat physical symptoms of Parkinson’s disease; it is also FDA approved to treat OCD, epilepsy, and the neurological disorder dystonia. In more recent years, it has also been used experimentally to treat major depression, Tourette syndrome, and other mood disorders such as bipolar disorder, though results have been mixed.
In general, brain stimulation therapies will be administered in a hospital or doctor’s office. Patients will usually undergo a physical exam and a psychiatric evaluation to determine their eligibility; additional lab tests may be required depending on the specifics of the procedure.
ECT is performed in a hospital by a psychiatrist, with the aid of an anesthesiologist and nurse. Prior to the administration of therapy, the patient is given a muscle-relaxing drug and general anesthesia. Through electrodes positioned on the scalp, electric current moves through the brain, intentionally causing a brief seizure.
ECT treatments are usually administered three times a week for up to about a dozen treatments. After each treatment, patients can usually leave the recovery room and resume normal activities within half an hour. Possible side effects include confusion, short-term memory loss, headache, or jaw pain. These side effects are usually temporary, especially now that more refined techniques are used to administer ECT; an older ECT technique, known as bilateral ECT, appears more likely to cause side effects than the newer unilateral technique, in which electrodes are placed on just one side of the head rather than both. Follow-up maintenance treatments are often required; patients may also be prescribed psychiatric medication to help maintain results.
VNS requires an electrical device to be surgically implanted under the skin to send impulses through the vagus nerve to the brain. Surgery can usually be done as an outpatient procedure, though some patients may be briefly admitted to the hospital while they recover. Once the device has been successfully implanted, it will be programmed by the doctor to deliver electrical pulses of a specific frequency on a regular schedule. Patients may be unaware when the device is on, but they may also experience side effects such as coughing, hoarse voice, or tickling in the throat during stimulation. Other side effects include headaches, insomnia, shortness of breath, or changes to the voice; side effects may also arise from the surgery itself and include lingering pain from the incision or an infection. Side effects can usually be managed and often lessen over time.
rTMS, like ECT, does not require invasive surgery. This procedure uses magnetic pulses, rather than electric currents, to stimulate the brain without inducing a seizure. During treatment, a doctor will first determine the best place to position the magnetic coil on the patient’s head and the patient’s “motor threshold,” or the power necessary to make the patient’s hand twitch; this is necessary to identify the patient's ideal dose. Once the procedure is underway, the patient may hear a tapping sound and/or feel a tapping sensation on their head. Generally, a session will last 30 minutes to an hour; afterward, patients should be able to resume normal activities right away. A typical course of TMS consists of 5 treatments a week for 4 to 6 weeks.
MST also uses magnetic pulses instead of electricity but, like ECT, causes an intentional seizure. Because MST is still being studied, the exact dose and treatment schedule needed to see results is not well understood. Currently, many research studies involve between 8 and 24 sessions. Side effects may include disorientation, memory loss, or the emergence of mania.
DBS uses electrodes that are surgically implanted in the brain and controlled by a generator implanted in the chest. During surgery, the surgeon will drill small holes in the patient’s skull to insert a number of electrodes into the brain, the location of which will depend on the condition being treated. In a follow-up surgery (which may happen at the same time or a short time later), surgeons will implant a pulse generating device in the patient’s chest and connect it to the electrodes in the brain. Once the devices have been safely inserted for a few weeks, the doctor will turn on the pulse generator and program the stimulation to the desired amount; once the patient leaves the doctor's office, they may be able to turn the device on and off or adjust the stimulation, per their doctor’s specific instructions.
Like other surgical procedures, DBS carries a risk of complications. After the devices have been successfully implanted, there is a small risk of possible side effects including headaches, confusion, difficulty concentrating, seizures, and stroke. The patient will need to return frequently for follow-up appointments and to replace the devices’ batteries periodically.
The mechanism of action for many brain stimulation therapies is not yet entirely understood. But in most cases, such therapies are thought to activate nerve cells in a controlled manner, producing both chemical and functional changes in the brain that can help reduce the severity of psychiatric or neurological symptoms. It has been proposed that VNS, in particular, works by curbing overactivity in certain regions of the brain and/or by stimulating an anti-inflammatory effect. (To learn more about vagus nerve stimulation, see Vagus Nerve.)
Earlier in its use, ECT developed a bad reputation and was widely derided as “shock therapy.” This is likely because it was sometimes administered at high doses or without proper sedation, leading to more severe side effects than are common today. Many institutionalized individuals were also treated without their consent. Fictionalized portrayals of ECT, such as that in the novels The Bell Jar and One Flew Over the Cuckoo’s Nest, further added to the procedure’s negative reputation.
While some stigma remains, however, the procedure has been greatly refined over the years and is considered a safe and effective treatment for severe cases of depression. It is generally only used with a patient’s informed consent, except in some extreme cases. While it is still often seen as a therapy of last resort and is almost never used as a first-line treatment, it may be prescribed in life-threatening circumstances, such as when a patient demonstrates no interest in feeding themselves and has become malnourished.
Other brain stimulation therapies such as rTMS, VNS, or DBS are generally considered safe as well, though as with any medical procedure they come with a risk of side effects. Efficacy varies; for example, about 30 percent of people with treatment-resistant depression achieve remission after a round of TMS, while for ECT, the success rate is closer to 80 percent. MST, as a relatively new treatment modality, is still being investigated to determine whether and in what cases the benefits outweigh the risks. Before pursuing any brain stimulation therapy, patients should speak extensively with their doctor about whether and which brain stimulation therapy is the right choice for them.
In seeking brain stimulation interventions, look for a licensed psychiatrist, neurologist, or neurosurgeon with experience in ECT, VNS, or other brain-stimulating therapies. He or she should be affiliated with a reputable hospital and brain stimulation program. A physician or psychiatrist who is familiar with the patient’s medical and psychiatric background generally refers candidates for brain stimulation therapy to a hospital program.