Rutgers University scientists have helped shed light on the mysterious link between epilepsy and depression — which has been the subject of speculation for more than 2,400 years — by determining that the potentially debilitating disorders likely share a genetic cause.
Working with researchers from New York’s Columbia University, experts in the genetics department at Rutgers-New Brunswick studied dozens of families with multiple relatives diagnosed with epilepsy and discovered that individuals with one form of the disease are more likely to suffer from depression.
Mood disorders are the most common condition diagnosed in conjunction with epilepsy, a neurological disorder associated with abnormal electrical activity in the brain that can cause seizures ranging from sensory disruption and loss of consciousness to severe convulsions. Studies have shown that those with depression tend to have worse seizure outcomes than those who don’t suffer from mental illness, Rutgers noted.
Rutgers professor Gary A. Heiman, the lead researcher, said more study is needed to identify the genetics the two conditions have in common. But the, published Wednesday in the medical journal Epilepsia, underscore the need for careful mental-health screening and comprehensive treatment among those already suffering from epilepsy.
“Mood disorders such as depression are under-recognized and undertreated in people with epilepsy,” explained Heiman, an associate professor in the department of genetics. Better treatment for behavioral health issues among this cohort “will improve patients’ quality of life,” he said.
Nationwide, some 3.4 million Americans have active epilepsy — having been diagnosed and regularly treated for the disease — including 470,000 children, according to 2015from the federal Centers for Disease Control and Prevention. In New Jersey, epilepsy impacts some 92,700 people, 12,000 of whom are under age 18.
Epilepsy can result from a head injury, tumor, or stroke, among other things, while seizures can also be triggered by withdrawal from drugs or alcohol. Treatment, which frequently involves medication and lifestyle modifications or surgery, is often effective, but some of the drugs involved have significant side effects of their own. Many patients are also restricted from driving, work, or other activities.
Healthcare providers have long noted the connection between epilepsy and depression, which affects more than 16 million Americans each year. In fact, Rutgers said that Hippocrates — a Greek physician considered the “father of medicine” — wrote about the link in 400 BC, using language of that day: “Melancholics ordinarily become epileptics, and epileptics, melancholics: what determines the preference is the direction the malady takes; if it bears upon the body, epilepsy, if upon the intelligence, melancholy.”
While epilepsy itself, and the impact of treatment, might conceivably cause mood issues, Heiman said several large population-based studies have also suggested those with depression might be more susceptible to epilepsy. That has led researchers like him to wonder about a potential biological connection between the two.
“I’m always interested in the ‘why’,” Heiman said.
The study involved 192 individuals from 60 families recruited by scientists at Columbia University; 110 of these subjects had epilepsy of an unknown cause and 82 did not have the condition. Researchers compared the depressive episodes reported by these groups with the public at large to determine any correlation between the two disorders.
The work revealed a potential connection, with an interesting twist. Scientists found that the 50 individuals with localized, or focal, epilepsy — which is limited to one side or section of the brain — were at far greater risk for developing depression than those who did not have epilepsy.
But the 42 study subjects who experienced generalized epilepsy — which impacts both lobes of the brain — did not indicate the same elevated risk for mood disorders. (A variety of seizures can result from both types of the disease; the treatments are largely the same.)
While it is not clear why only one form of the disease exhibited this increased risk, Heiman said the findings support the theory that epilepsy and depression share a common genetic origin. (The study did not show a causal effect, or that one disease leads to the other, he stressed.)
Other research has shown epilepsy can run in some families, Heiman added, but more work is needed to determine what genes are involved, or how these could also connect to depression or other mood disorders.
“A number of genes have been found for epilepsy, and understanding if these genes also might be causing depression is important,” he said. "In particular, more studies should be done to understand the relationship between focal epilepsy and mood disorders."