The unclear interhemispheric modulation of mood: A response to Doherty et al. on predicting mood decline following temporal lobe surgery in adults

Abstract

To the Editors: The preoperative and postoperative lateralization of mood in focal epilepsy has been controversial. Doherty et al.1 added a valuable contribution with the statistical modeling of postoperative depression in more than 500 patients who underwent temporal lobe surgery. They found that the risk of postoperative depression measured by the Beck Depression Inventory (BDI)– second edition was greater in those who underwent surgery of the dominant side. Doherty et al. failed to include studies, however, that evaluated longitudinal changes. Devinsky et al.2 acquired a prospective cohort (N = 358) studied before and after resective surgery; side had no effect on the presence of depression preor postoperatively measured with the BDI (first edition). These findings were supported by an earlier retrospective study that used the Diagnostic and Statistical Manual of Mental Disorders– third edition revised.3 A study that tracked mood with the same instrument, in contrast, found that rightsided resections were at higher risk for major postoperative psychiatric complications.4 Our own group evaluated a cohort (N = 108) of patients with mesial temporal lobe epilepsy who underwent anterior temporal lobectomy.5 We created a summary score of psychiatric consequences of depression (selfreported depression, physician intervention for depression, or attempted or completed suicide) obtained during preoperative screening and assessed 1 year after surgery. Worse preoperative symptoms predicted severity of postoperative symptoms. Rightsided epilepsy surgery patients experienced more postsurgical psychiatric morbidity or mortality than did leftsided patients, accounting for verbal intelligence quotient in the statistical model. We conclude that the interhemispheric modulation of mood remains unclear. One implication is that selfreported inventories such as the BDI may differ from behavioral markers (psychiatric treatment, suicide attempts or completion) of psychiatric morbidity or mortality in patients with epilepsy. We recommend that preoperative counseling and postoperative monitoring remain high priorities of an epilepsy surgery program regardless of epilepsy syndrome or lateralization.