Electroconvulsive therapy (ECT), often called shock therapy, works by sending a brief electrical current through the brain to trigger a controlled seizure lasting 25 to 75 seconds. That seizure sets off a cascade of changes in brain chemistry, connectivity, and structure that can rapidly relieve severe depression, catatonia, and other psychiatric conditions when medications haven’t worked. It’s one of the most effective treatments in psychiatry, with response rates between 70% and 90% in treatment-resistant depression, yet it remains widely misunderstood.
How It Changes the Brain
The induced seizure doesn’t simply “reset” the brain like flipping a switch. It triggers several overlapping biological changes that researchers are still working to fully map. The most prominent theory centers on neuroplasticity: ECT increases the brain’s production of a growth protein called BDNF, which stimulates the creation of new neurons and strengthens connections between existing ones, particularly in the hippocampus, a region involved in mood regulation and memory.
MRI studies consistently show that the hippocampus increases in volume after ECT. Recent animal research found this volume change isn’t primarily from new neurons being born. Instead, it appears driven by an increase in the density of synapses (the junctions where brain cells communicate) in specific hippocampal subregions. In other words, ECT seems to physically rebuild communication infrastructure in parts of the brain that depression has weakened.
ECT also reshapes brain chemistry. It boosts serotonin signaling in the hippocampus and prefrontal cortex, increases the activity of GABA (the brain’s main calming chemical), and activates the dopamine system, which plays a role in motivation, concentration, and the ability to feel pleasure. On a network level, brain imaging shows ECT dials down overactive connections in the default mode network, a circuit linked to rumination and self-referential thinking, while strengthening networks involved in attention and problem-solving.
What It Treats
The FDA classifies ECT devices for two main uses in patients 13 and older: severe major depressive episodes (associated with major depressive disorder or bipolar disorder) and catatonia. In both cases, it’s indicated when the patient either hasn’t responded to other treatments or needs rapid improvement because their condition is life-threatening. That second category matters. ECT can produce noticeable improvement within days, while most antidepressants take weeks to reach full effect. For someone who is actively suicidal or refusing to eat or drink due to catatonia, that speed can be lifesaving.
In practice, clinicians also use ECT for severe mania and certain presentations of psychosis, though the FDA classification focuses on depression and catatonia. Among patients with treatment-resistant depression, one study found an overall response rate of 85.7%, with full remission in about 55% of patients.
What the Procedure Feels Like
Modern ECT bears little resemblance to the dramatic depictions in older films. You’re put under general anesthesia, so you’re completely unconscious and feel nothing during the procedure. A muscle relaxant prevents the violent physical convulsions that once made the treatment look so alarming. The seizure itself is mostly visible only on an EEG monitor; outwardly, your body may show only slight twitching in the hands or feet.
The entire session, from anesthesia to waking up, takes roughly 15 to 20 minutes. You’ll typically wake in a recovery area feeling groggy and possibly confused, similar to coming out of any brief anesthesia. Some people experience a headache, nausea, or muscle soreness afterward. A standard acute course involves treatments two to three times per week over several weeks, usually totaling 6 to 12 sessions depending on how quickly symptoms improve.
Electrode Placement and How It Affects Results
Where the electrodes are placed on the head influences both effectiveness and side effects. Bilateral placement (one electrode on each side of the head) has historically shown slightly higher response rates, around 78% compared to about 72% for right unilateral placement (both electrodes on the non-dominant side). However, in clinical practice, the difference in depression scores at discharge is statistically small and often not clinically meaningful. Unilateral placement tends to cause fewer cognitive side effects, so many clinicians start there and switch to bilateral if the patient doesn’t respond adequately.
Memory and Cognitive Side Effects
Memory disruption is the side effect that concerns people most, and it’s a real one. There are two distinct types. Anterograde amnesia, difficulty forming new memories, is common in the days and weeks during a treatment course but typically resolves after sessions end. Retrograde amnesia, the loss of memories formed before treatment, is more variable and more distressing. It tends to affect memories closest in time to the treatment period. For most people, these gaps fill in over weeks to months, but some patients report persistent blank spots, particularly around the weeks of treatment itself.
People with stronger cognitive reserves before treatment tend to experience less memory disruption. How quickly you reorient after each session is also a useful predictor: patients who take longer to “come to” after the anesthesia wears off tend to have more retrograde memory issues both in the first week and at two-month follow-up. Your treatment team will monitor orientation and memory throughout the course and can adjust electrode placement or treatment frequency if side effects are significant.
Physical Safety
ECT carries the risks inherent to any procedure involving general anesthesia, but serious complications are uncommon. A large meta-analysis found that all-cause mortality runs about 6 deaths per 100,000 treatments. Cardiac events are the most common serious complication: life-threatening heart rhythm disturbances occur in roughly 5 per 1,000 treatments, acute heart failure in about 2.5 per 1,000, and heart attacks in about 1 per 1,000. These numbers mean that for the vast majority of patients, especially those without pre-existing heart conditions, the physical risk is low relative to the severity of the illness being treated.
Staying Well After Treatment
The biggest challenge with ECT isn’t getting better. It’s staying better. Without follow-up treatment, relapse rates are high. Most patients are started on medication after completing an acute ECT course to maintain remission. For those who relapse despite medication, or who have a history of severe repeated episodes, maintenance ECT is an option. This involves continued sessions at a lower frequency, typically once a week or less, tapered over time.
Data from patients receiving maintenance ECT alongside medication showed relapse rates of about 12% at three months, 20% at six months, 30% at one year, and 40% at two years. These numbers are considerably lower than relapse rates with medication alone, though they underscore that ECT is not a permanent cure. Maintenance plans are typically reviewed every 6 to 12 months to weigh ongoing benefits against the cumulative burden of repeated treatments.