After years of consideration, the Food and Drug Administration has determined that for carefully selected patients with profound depression, the benefits of electroconvulsive therapy, long demonized, outweigh the risks of possible memory loss caused by its use.

Citing evidence from 60 randomized trials of ECT, once known as electroshock therapy, the FDA acknowledged the risk but said that there is now enough evidence to ease access to the therapy for certain people.

The devices that are used to administer ECT are regulated by the agency as Class III. That is the highest-risk designation, and it makes the equipment subject to the highest level of regulatory control. The FDA is proposing to downgrade that assessment to Class II for those whose depression has not responded to other treatments or is so severe that they need the kind of rapid response that only ECT can provide.

For other medical conditions – including catatonia, a stuporlike state of immobility for which ECT is considered by some psychiatrists to be one of the few effective treatments – the FDA said that too few randomized trials have been published to justify a Class II designation.

An estimated 100,000 of the 3 million people in the United States with treatment-resistant depression undergo ECT each year, a figure that could rise if the proposed new designation is finalized. By generating a brief pulse of electricity to the brain, the devices induce a generalized seizure. For reasons not fully understood, the result is that many patients feel better afterward.

The new assessment would bring to a close decades of wrangling over how best to regulate the controversial treatment. The FDA first proposed to classify ECT as Class II in 1978, before backing away after public opposition arose. It tried again in 1990 but did not finalize the change. In 2011, it invited an advisory panel to consider the issue again.

After two days of hearings, that panel voted, 10 to 8, against easing the classification, saying that not enough was known about the risks and benefits of ECT devices and that more research was needed.

Although the FDA generally follows the recommendations of its advisory panels, the agency finally decided against accepting that advice, publishing its proposal to ease the classification in the Federal Register on Dec. 28 of last year. The change could go into effect at any point, because the three-month waiting period for public comment expired March 28.

Prior to the advisory panel’s meeting in 2011, the FDA said it had received more than 3,000 comments from patients, family members of patients, researchers and others. About 80 percent of those comments opposed an easing of controls.