A Longitudinal Comparison Between Depressed Patients Receiving Electroconvulsive Therapy and Healthy Controls on Specific Memory Functions.

OBJECTIVE

To examine the short- and long-term effect of electroconvulsive therapy on verbal, visual, and autobiographical memory functions in patients treated for a severe depressive episode. Patients were compared with healthy controls undergoing neurocognitive assessments at the same time points to account for normal forgetfulness and potential learning effects.

METHODS

A pre-post intervention design included patients (n = 38) and controls (n = 16) referred to Haukeland University Hospital for electroconvulsive therapy (ECT) from September 2013 to September 2018. Patients diagnosed with a major depressive episode (according to ICD-10 criteria) underwent right unilateral ECT with brief-pulse, square-wave, constant current. Neurocognitive assessments were administered pretreatment and, on average, 19 days and 6 months posttreatment. Performance on the California Verbal Learning Test Second Edition, Rey Osterrich Complex Figure, and Autobiographical Memory Interview-Short Form were the main outcome measures, examining verbal, visual, and autobiographical memory, respectively.

RESULTS

Patients performed significantly worse compared to controls on all measures of verbal and visual memory at every assessment (P ≤ .001). Within-group analyses showed no impaired visual or verbal memory function due to ECT. However, autobiographical consistency was significantly decreased for patients (70.30%) compared to controls (82.03%) 6 months posttreatment (P = .0005).

CONCLUSIONS

Patients' ability to acquire new general knowledge is considered as unaffected by ECT. Deficits in autobiographic memory were found 6 months posttreatment, indicating both an iatrogenic effect of treatment and an effect of depression on retrograde memory functions. For patients, the risk of this iatrogenic effect of treatment must be evaluated against the symptomatic and potential functional recovery due to ECT.

TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT04348825.