ECT Does Not Increase Risk of Dementia

Electroconvulsive therapy (ECT) is a highly effective treatment for severe cases of mood disorders, but the technique is known to come with some risks, including memory loss.

Although most cognitive deficits tend to resolve within weeks of therapy, several small studies have suggested patients who receive ECT may be at risk of long-term adverse cognitive outcomes; however, these studies did not take into account that severe depression is itself a risk factor for dementia.

The results of a study in the April issue of Lancet Psychiatry suggest ECT does not increase long-term dementia risk, even in older patients with depression—a patient population known to be at a high risk of dementia.

Merete Osler, D.Msc., of the Center for Clinical Research and Prevention at the Bispebjerg and Frederiksberg Hospitals in Denmark and colleagues used the Danish National Patient Registry to identify 168,015 patients aged 10 or older who were hospitalized with a first-time diagnosis of a mood disorder between 2005 and 2015. Of these patients, 5,901 (3.5 percent) underwent at least one ECT session.

During the follow-up period (about five years per patient, on average), 3.6 percent of the patients who received ECT developed dementia compared with 3.1 percent of people with a mood disorder who did not receive ECT. This resulted in dementia incidence rates of 70.4 cases per 10,000 person-years in patients who received ECT and 59.2 cases per 10,000 person-years in patients who did not receive ECT.

While this baseline dementia rate was slightly higher among ECT recipients, this difference disappeared once the authors used a tool known as propensity score matching to address disparities between the two populations; for example, the ECT group had higher rates of severe depression or psychotic depression, while the non-ECT group had higher rates of stroke.

Potentially vulnerable subgroups, such as depression patients aged 70 or older or patients who received 10 or more ECT sessions, also did not appear to be at any greater risk of dementia, the researchers found.

“The potential adverse effects of ECT on cognitive function might have fueled the fear of dementia in patients and clinicians, and for that reason they might hesitate to choose ECT as a treatment. The findings from this study show that, notwithstanding other possible adverse long-term cognitive effects, ECT did not increase the risk of dementia and support the continued use of ECT in patients with severe episodes of mood disorders, including those who are elderly,” the authors wrote.

“Osler and colleagues were scrupulous in their analysis, in particular the use of propensity score matching,” noted Peter Rosenquist, M.D., a professor and executive vice chair of psychiatry at Augusta University in Georgia. “This trumps earlier studies that implied the rate of dementia in an ECT-treated population exceeded that of the general population.”

He continued, “Will these findings silence all the skeptics who claim that ECT causes dementia or brain damage? Perhaps not, but it is certainly helpful to have these results from a large dataset and well-conducted methodology to counter continued misinformation.”

Rosenquist also emphasized that temporary memory loss from ECT needs to be viewed in the broader context of patient health and daily living: “To put it simply, major depression destroys one’s quality of life, and ECT restores it,” he told Psychiatric News. “While side effects are an important concern, they are overshadowed by the relief that evidence-based treatments provide.”

The finding that memory loss following ECT appears to be transient should make conversations about ECT as a treatment for mood disorders easier between doctors and patients, he said.

The study by Osler and colleagues was supported by the Danish Council for Independent Research, the Danish Medical Research Council, the Velux Foundation, the Jascha Foundation, and the Doctor Sofus Carl Emil Friis and Olga Doris Friis grant. ■