Profiling the evolution of depression after epilepsy surgery

Abstract

Both neurobiologic and psychosocial factors have been proposed to account for the high prevalence of depression surrounding epilepsy surgery. Using a prospective longitudinal approach, this study aimed to profile the evolution of depression after epilepsy surgery at multiple time points, including early and longer-term follow-up. We also sought to identify neurobiologic and psychosocial predictors of depression before and after surgery, including whether patients undergoing mesial temporal lobe resection (MTR) were at greater risk of depression than patients undergoing nonmesial temporal lobe resection (NMTR). Sixty patients undergoing epilepsy surgery (38 MTR, 22 NMTR) for the treatment of medically intractable seizures were assessed preoperatively and at 1, 3, 6, and 12 months postoperatively in the Comprehensive Epilepsy Program of Austin Health. The diagnosis of depression was based on DSM-IV criteria for major depressive disorder, as assessed from a mental state examination. The Austin CEP Interview was used to obtain a detailed psychosocial assessment of each patient and family members. Before surgery, 43% of patients had a lifetime prevalence of depression, with no difference between the proportion of patients in the MTR (40%) and NMTR groups (50%). Predictive factors included a family history of psychiatric illness (p = 0.015) and financial dependence of either family members or government income benefits (p = 0.024). Discriminant function analysis indicated that these factors classified 69% of cases correctly (p = 0.006, partial η(2) = 0.06). In the 12 months following surgery, 37% of MTR and 27% of NMTR patients experienced major depression, with no significant difference between the two groups. The majority of depressed patients (70%) were diagnosed in the first 3 months and in 65% of diagnosed cases, the depression persisted for at least 6 months within the follow-up period. The pattern of recurrent and de novo depression differed significantly between the groups, with 13% of MTR patients developing de novo major depression in comparison to no NMTR patients (p = 0.05). A preoperative history of depression (p = 0.003) and poor postoperative family dynamics (1 month, p < 0.001; 3 months, p = 0.007; 6 months, p = 0.021; 12 months, p = 0.097) were predictive of depression after surgery. These factors correctly classified 78% of cases (p = 0.000, partial η(2) = 0.19). The findings of this study confirm high rates of major depression before and after epilepsy surgery, the etiology of which is multifactorial. They highlight the need for thorough assessment and diagnosis before surgery, as well as the provision of routine follow-up and psychological support, particularly early after surgery. When estimating level of risk for depression, patients should be counseled about the role of both neurobiologic and psychosocial factors. Before surgery, these include a family history of psychiatric illness and financial dependence, whereas poor family adjustment to life after surgery and a patient preoperative history of depression were risk factors for postoperative depression. Finally, disruption to mesial temporal structures known to play a role in mood via MTR may place patients at increased risk of new-onset depression after surgery.