Changes in everyday and semantic memory function after electroconvulsive therapy for unipolar depression

This long-term prospective study focuses on the effects of electroconvulsive therapy (ECT) on everyday memory function and on semantic memory function.

Results of memory test from 96 consecutive inpatients treated for unipolar depression were analyzed prospectively before ECT, after ECT treatment, and at 3- and 12-month follow-up. Everyday memory function was assessed by means of the Rivermead Behavioural Memory Test (RBMT) and semantic memory by 2 forms of the word fluency test.

In our study, age had a constant and significant negative effect on everyday memory (RBMT score) over time. Bilateral electrode placement mainly influenced everyday memory, which was significantly improved at 3-month follow-up. One year after discharge, the RBMT scores were not significantly different from pretreatment levels, indicating that ECT does not affect everyday memory on the longer term. Scores on both word fluency tests for semantic memory were significantly influenced by age over time. The effect of age changed from a negative influence directly after ECT to a positive effect at follow-up. This advantage of higher age indicates that the semantic memory of older patients receiving ECT for severe mood disorder shows greater improvement at follow-up compared with younger patients. Over time, the scores on only 1 of the word fluency tests were significantly influenced by mainly bilateral electrode placement.

A small but reversible decrease in everyday memory occurs after ECT in depressed patients, which is influenced by age and electrode placement. Semantic memory shows a fluctuating but recovering course, which is also influenced by age and electrode placement. During follow-up, the improvement in semantic memory was greater in the older patients.