Study Links Epilepsy and Schizophrenia Risk
But an Expert Calls the Risk 'Fairly Low'
June 16, 2005 -- There is a "strong association" between epilepsy
and schizophrenia, says a Danish study of more than 2 million people.
People with epilepsy had about 2.5 times the risk of schizophrenia as the
general population, says the study, which is posted on BMJ Online First.
Yet that's "fairly low," says Charles Raison, MD. Most people with
epilepsy probably aren't in danger of schizophrenia, he says.
Raison directs the Behavioral Immunology Clinic at Emory University's
medical school. Previously, he was a consulting psychiatrist for the epilepsy
service at the University of California at Los Angeles (UCLA).
Raison didn't work on the study, but he read it and put it in perspective
for WebMD. He says he wasn't surprised to see a higher risk for epilepsy
patients and that clinicians should consider seizures as a possible factor in
psychotic patients. "I always wonder about that when we see new onset of
psychosis," he says.
Risk Is Still Small for Patients
The increased risk "doesn't mean that patients are going to go
insane," says Raison.
He says that schizophrenia risk is very small -- about 1%, in general. But
even with the higher risk cited in the study, people with epilepsy still have
only a 2-3 in 100 chance of developing schizophrenia. "That's of some
concern," says Raison, but "you can get a large increase in risk [and]
if the risk is small, you're still very safe."
Put it this way, says Raison: "If I told you you had a 2.5% chance of
winning a million bucks in the lottery, you might be excited, but you'd be an
idiot to quit your job."
The Danish study was based on records in a national database of more than
2.2 million people age 15 and older. Researchers reviewed their histories until
December 2002, or until they died or were diagnosed with schizophrenia or
Very few people (1.5%) had epilepsy and only a sliver of them had
schizophrenia or related psychosis. Of the epilepsy patients, fewer than one in
a hundred (0.8%) were admitted to a hospital for schizophrenia, and 1.5% were
admitted for schizophrenia-like psychosis.
The risk was similar for men and women, and for all types of epilepsy. Age
and family history of epilepsy or schizophrenia were important. The risk rose
with age and was higher in those with no family history of psychosis.
Hospital treatment is free for all Danish residents, so economic factors
shouldn't have interfered, say the researchers. They included Ping Qin, an
associate professor at Denmark's University of Aarhus.