Depression stalks "incurable" epileptics

Low quality-of-life scores of those with uncontrolled symptoms are traced to depression. Researchers urge treatment

By S H Cyr

It seems natural enough to assume that the first goal of treatment for an epileptic patient should be to reduce the frequency of seizures. Unsurprisingly, research has consistently shown patients who become seizure-free have a quality of life similar to that of the general population.

Now research published in the January issue of Neurology suggests that among patients who don't respond to treatment, frequency of seizures is not the determining factor in quality of life. Rather, the study found that it's depression that impacts these patients the most. Not only is depression common among patients with epilepsy, the antiepileptic drugs (AEDs) themselves tend to exacerbate the problem. The newer AEDs all showed association with increased risk of depression in clinical trials.

Overall, about one-third of epileptic patients stop having seizures when treated. A further third achieve a significant reduction in seizure frequency. That leaves one-third for whom AEDs are largely ineffective. This does not mean that, as a rule, these patients stop taking the drugs. Instead their physicians try different medications in an attempt to control the symptoms.

Previous research on quality of life in epilepsy has usually excluded patients diagnosed with depression. Moreover this research tends to include patients whose symptoms are well controlled alongside those who still suffer frequent seizures. These studies have found a correlation between lower seizure frequency and better quality of life.

Researchers from the New York University School of Medicine and others set out to look at the impact of depression on quality of life in patients whose epilepsy is not under control. They recruited 122 patients who answered the ubiquitous Beck Depression Inventory (BDI), the most common quick test for depression. Subjects also completed the Quality of Life in Epilepsy Questionnaire (QOLIE-31). The results dramatically confirmed the investigators' suspicions that depression is both widespread and debilitating among this population.

No fewer than 54% of these patients suffered from depression according to their BDI scores. Of these, only 37% had ever been diagnosed and only 17% were taking antidepressants. Yet the depression found in this group was, on average, moderate to severe and 19% of them reported suicidal thoughts.

The researchers looked at a range of factors to calculate their impact on the quality of life score: age, sex, marital status, seizure frequency, epilepsy type (localisation related or primary generalised), lobar localisation (temporal or extratemporal), presence/absence of any generalised seizures, seizure laterality (right or left or bilateral), duration of epilepsy, age at time of first unprovoked seizure, number of AEDs, previous diagnosis of depression, current antidepressant use and BDI.

Remarkably, the only measure that had any significant effect on quality of life score was depression as measured by the BDI. In fact, BDI score was a highly significant predictor of quality of life scores in all seven domains of the QOLIE-31 questionnaire. Seizure frequency, on the other hand, didn't affect quality of life scores.

This surprising finding is particularly significant because antiepileptic medication is not controlling these patients' seizures and could actually be causing their depression. That said, the authors don't call for such patients to be taken off AEDs. Rather, they suggest that better diagnosis and treatment of depression is a possible route to improving the lives of epileptic patients even when the physician can't reduce seizure frequency. These patients' depression was seriously underdiagnosed, and where diagnosed, was undertreated.

"Despite the introduction of many new medications in the last decade, new treatments have had a negligible impact on the number of patients attaining seizure freedom," concluded the authors. "For many patients with refractory epilepsy, there is no known treatment that can raise QOL to levels near those of the general population. Our findings indicate that greater attention to the treatment of depression in this population may be one method of filling that void."