Electroconvulsive therapy (ECT) works by sending a brief, controlled electrical current through the brain to trigger a short seizure, typically lasting 30 to 60 seconds. That seizure sets off a cascade of chemical and structural changes in the brain that can relieve severe depression, catatonia, and other psychiatric conditions when medications have failed. The treatment has a response rate of about 66% even in people whose depression hasn’t improved after multiple medication trials.
What Happens During the Procedure
ECT is done under general anesthesia, so you’re completely unconscious and feel nothing during the treatment. An anesthesia team puts you to sleep using a fast-acting sedative delivered through an IV. The entire period of unconsciousness lasts roughly 5 to 10 minutes.
Once you’re asleep, you receive a muscle relaxant. This is a critical step: without it, the seizure would cause full-body muscle contractions strong enough to cause injuries or severe soreness. With the relaxant on board, the visible signs of the seizure are minimal, often just a slight twitching in the hands or feet. A blood pressure cuff is sometimes inflated around one ankle before the relaxant is given so that doctors can observe the seizure’s effect on that foot, confirming the seizure occurred.
The psychiatrist then places electrodes on your scalp and delivers a short electrical pulse. The resulting seizure is monitored on an EEG. The whole procedure, from falling asleep to waking up, typically takes about 10 to 15 minutes, though you’ll spend additional time in a recovery area as the anesthesia wears off.
Electrode Placement and Pulse Settings
Where the electrodes go on your head matters. The two most common placements are unilateral (both electrodes on the same side, over the non-dominant hemisphere) and bilateral (one electrode on each side, either at the temples or toward the front of the head). Both approaches work. In a randomized trial of ultra-brief pulse ECT, about 78% of patients responded regardless of whether they received unilateral or bilateral placement. Patients who received unilateral ECT tended to reach response or remission in fewer sessions.
The width of the electrical pulse also plays a role. Modern ECT increasingly uses “ultra-brief” pulses, which are shorter than traditional brief-pulse settings. This approach appears to maintain effectiveness while reducing the cognitive side effects that made earlier forms of ECT more burdensome. The electrical dose is calibrated to each patient, typically set at a specific multiple above the minimum amount needed to trigger a seizure.
How ECT Changes the Brain
The honest answer is that no one has pinpointed a single mechanism. ECT appears to work through several overlapping biological pathways, and the cumulative effect of these changes is what lifts symptoms. The leading theory, called the neuroplasticity hypothesis, holds that the seizures stimulate the brain to grow new neurons and strengthen connections between existing ones, essentially helping the brain repair circuits that depression has impaired.
One key player is a protein called brain-derived neurotrophic factor (BDNF), which acts like fertilizer for brain cells. ECT boosts production of BDNF, which in turn promotes the growth of new neurons in the hippocampus (a region central to memory and mood regulation) and encourages existing neurons to sprout new connections. Animal studies show that repeated ECT sessions produce a dose-dependent increase in new neuron growth in the hippocampus.
ECT also reshapes the brain’s chemical signaling. It increases the activity of the calming neurotransmitter GABA, which may explain some of its anxiety-reducing effects. It normalizes levels of glutamate, the brain’s primary excitatory chemical, in mood-regulating regions. It enhances signaling in the serotonin and norepinephrine systems, the same pathways targeted by most antidepressant medications, and activates the dopamine system, which is involved in motivation and pleasure. These changes don’t happen through a single receptor or pathway. They unfold across multiple brain regions simultaneously, which may be why ECT can succeed where drugs that target just one system have failed.
How Well It Works
ECT is the most effective acute treatment available for severe depression. In patients who have never tried other treatments, response rates reach about 82%, with roughly 35% achieving full remission. For people with treatment-resistant depression, defined as those who haven’t responded to multiple medications, the numbers are lower but still substantial: about 66% respond and around 16% reach remission. The more medication trials a person has been through without improvement, the lower the expected response rate drops, falling to about 63% after five or more failed trials.
Beyond depression, ECT is used for bipolar disorder (both depressive and manic episodes), catatonia, and situations where a rapid response is essential, such as severe suicidality or refusal to eat or drink. For catatonia in particular, ECT often produces dramatic improvement within just a few sessions.
What a Treatment Course Looks Like
A typical acute course involves two to three sessions per week, usually totaling 6 to 12 sessions over several weeks. Some people notice improvement after just a few treatments, while others need the full course before symptoms lift meaningfully.
Once the acute course ends, the risk of relapse is real. To reduce that risk, many psychiatrists recommend maintenance ECT, where sessions continue on a gradually tapering schedule. A common approach starts with weekly treatments for four weeks, then shifts to every two weeks for about eight weeks, then monthly for a couple of months. Some patients stay on monthly or every-six-week maintenance sessions for much longer. An alternative approach uses “rescue” sessions, where treatment is given only when early signs of relapse appear rather than on a fixed schedule.
Memory and Cognitive Side Effects
Memory disruption is the side effect people worry about most, and it’s a real concern, though more nuanced than the popular image of ECT suggests. Two types of memory are affected in different ways and on different timelines.
The ability to form and retain new memories (anterograde memory) is impaired during a course of ECT and for a short window afterward. This effect is temporary. Most studies show it returns to baseline within about two weeks of the final treatment. During a course of ECT, you may find it harder to remember conversations from earlier that day or retain new information. This clears up relatively quickly.
Loss of older memories (retrograde amnesia) is more variable and more distressing when it occurs. This can include both personal memories of things you experienced and factual knowledge. Memories from the weeks or months closest to the treatment period are most vulnerable. Most of this improves significantly within six months, but some autobiographical memories, particularly from the period around treatment, may not fully return. Depression itself also impairs memory, which can make it difficult to tease apart what is caused by ECT and what was already a symptom of the illness.
Cognitive functions beyond memory, such as attention and processing speed, tend to recover faster. When tested 4 to 14 days after a course of ECT, most cognitive measures have improved compared to pre-treatment levels, likely because the depression itself was dragging those abilities down.
Safety Profile
ECT carries the risks of any procedure involving general anesthesia, but the mortality rate is extremely low. A systematic review pooling data across multiple studies estimated 2.1 deaths per 100,000 treatments. To put that in context, in studies published after 2001, covering more than 414,000 treatments, only a single ECT-related death was reported. Common short-term effects include headache, nausea, muscle soreness, and temporary confusion immediately after the session, most of which resolve within hours.