Epilepsy Diagnosis, Outcomes Associated With Depression Severity

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Study findings suggest that epilepsy and depression may share a pathophysiological mechanism.
Study findings suggest that epilepsy and depression may share a pathophysiological mechanism.

Depression that requires treatment may be associated with a greater risk of developing epilepsy and may influence seizure outcomes, according to research published in JAMA Neurology.1

Community-based studies of epilepsy have demonstrated a 23.1% prevalence of depression, as well as a higher prevalence of depression before and after a diagnosis of epilepsy. Therefore, it has been suggested that epilepsy and depression could share a common pathophysiological mechanism. However, no studies have investigated the risks of developing epilepsy after a depression diagnosis.

Colin Josephson, MD, from the O'Brien Institute for Public Health and the Department of Clinical Neurosciences at the Cummings School of Medicine in Calgary, Alberta, Canada, and colleagues sought to understand the effect depression has on risk for epilepsy and seizure outcomes.

The investigators conducted an observational study involving a cohort of primary care patients using prospective data from the Health Improvement Network (THIN) database of the United Kingdom and the Calgary Comprehensive Epilepsy Program.

Within the THIN cohort, the investigators identified 229,164 patients (2.2%) who developed depression and 97,177 patients (0.9%) who developed epilepsy, with a mean age of 44 and 56 years, respectively. Patients with depression or epilepsy were more likely to be female (63% and 56%, respectively; P <.001 for both). Analysis of the THIN data demonstrated a higher hazard of developing incident depression in those with incident epilepsy compared with those without epilepsy (hazard ratio [HR], 2.04; 95% CI, 1.97-2.09; P <.001).

Further, there was a significantly higher hazard of developing epilepsy in those with incident depression after controlling for age, sex, comorbidity index, and socioeconomic status (HR, 2.54; 95% CI, 2.48-2.60; P <.001). The HR for epilepsy was greater in those with treated depression compared with those without depression or those not requiring treatment for depression (HR, 3.42; 95% CI, 3.37-3.47; P <.001). The hazard increased on the basis of the type of depression treatment; there were lower risks for counseling alone (HR, 1.84) and antidepressants alone (HR, 3.43), but a greater risk for those who were treated with both (HR, 9.85).

In the Comprehensive Epilepsy Programme, a history of current or past depression was tied to higher odds of not achieving 1-year seizure freedom compared with those without depression (odds ratio [OR], 1.41; 95% CI, 1.03-1.96; P =.03). Similarly, those treated with antidepressants or counseling had higher odds of not achieving 1-year seizure freedom (OR, 1.75; 95% CI, 1.06-2.94; P =.03).

"Using depression treatment as a surrogate of severity, we found that worsening depression appears to augment the risk of epilepsy and the odds of worse seizure outcomes. Future prospective studies designed to address causation between depression and epilepsy are warranted," the investigators concluded.

Reference

Josephson CB, Lowerison M, Vallerand I, et al. Association of depression and treated depression with epilepsy and seizure outcomes: a multicohort analysis. JAMA Neurol. 2017;74(5):533-539. doi: 10.1001/jamaneurol.2016.5042

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