Investigation of cognitive side effects of electroconvulsive therapy in patients with unipolar and bipolar depression

Cognitive side effects of electroconvulsive therapy (ECT), which is known to be a rapid and effective treatment method, is one of the reasons for reluctance to this treatment. The aim of this study is to determine the cognitive side effects of ECT in the short and long term, to examine how long these side effects continue after treatment and whether they are permanent and to investigate the factors that help to predict the cognitive side effects. This study was conducted at Hacettepe University Faculty of Medicine Department of Psychiatry, in a naturalistic design which included patients with unipolar and bipolar depression who were treated with ECT between January 2017 and November 2018. The patients included in the study were informed about the study, a consent form was signed on their voluntary participation, and the diagnosis was confirmed with SCID-I (Structured Clinical Interview for DSM-IV Axis I Disorders-Structured Clinical Interview Form for DSM-IV). Patients were given a Standardized Mini Mental Test (SMMT) for general cognitive assessment. The severity of depression was measured with the Montgomery-Asberg Depression Rating Scale (MADRS) and Clinical Global Impression Scale (CGI), and the degree of resistance to treatment with the Antidepressant Treatment History Form (ATHF). Cognitive side effects of the treatment were investigated with Benton Visual Retention Test (BVRT), Stroop test, Wechsler Adult Intelligence Scale (WAIS) comprehension, similarities, digit span, coding subscales and verbal fluency test. The patients were evaluated four times before ECT, within 3-7 days after ECT, 3 months and 6 months (V6) after ECT. A total of 38 patients, 24 of whom had unipolar depression, the remaining 14 had bipolar depression, were included in the study. Treatment of patients continued for a minimum of 3 weeks and a maximum of 6 weeks (5-13 sessions). No statistically significant difference was found between patients diagnosed with unipolar and bipolar depression with respect to age, gender, total education duration, age at disease onset, total number of depressive episodes, ATHF, MADRS and CGI scale scores. In terms of ECT parameters, there was no significant difference between the groups. It was observed that the patients who remitted or responded to the treatment had shorter postictal re-orientation times than the patients who did not respond to the treatment. There was a significant decrease in MADRS and CGI scores compared to the baseline in both groups. Findings show that ECT has no negative effect on visual memory, working memory and attention. Although there was a statistically insignificant deterioration in the verbal fluency test evaluating executive functions immediately after ECT, the test scores exceeded the initial values in the 3rd and 6th months after treatment. Stroop scores, another test evaluating executive functions, improved after ECT, and there was a significant improvement in the 6th month compared to baseline measurements. In the WAIS-coding subscale, which evaluates visual processing speed, short-term visual memory and attention, a significant improvement was detected in the total group at the 6th month compared to the baseline. The WAIS-similarities subtest, which evaluates verbal concept formation and verbal abstract reasoning and, WAIS comprehension subtest, which evaluates social knowledge and practical judgment in social situations were not affected by ECT. Keywords: Electroconvulsive therapy, depression, cognitive side effects, visual memory, working memory, attention, executive functions