Study finds bidirectional relationship between schizophrenia and epilepsy
Researchers from Taiwan have confirmed a bidirectional relation between schizophrenia and epilepsy. The study published today in Epilepsia, a journal of the International League Against Epilepsy (ILAE), reports that patients with epilepsy were nearly 8 times more likely to develop schizophrenia and those with schizophrenia were close to 6 times more likely to develop epilepsy.
Prior clinical studies have shown a prevalence of psychosis among epilepsy patients and studies of psychiatric illness have found a strong relationship between schizophrenia and epilepsy, suggesting a shared susceptibility between the diseases that may be a result of genetic, environmental or neurobiological causes. While a number of studies have established a bidirectional relationship between depression, mood disorder and epilepsy, the current study is the first to investigate this type of relation between schizophrenia and epilepsy.
Using data from the Taiwan National Health Insurance database, the team identified 5195 patients with schizophrenia and 11527 patients with epilepsy who were diagnosed between 1999 and 2008. The patient groups were compared to age and sex-matched controls. Analysis included the incidence and risk of developing epilepsy in the schizophrenia patient group and schizophrenia in the epilepsy cohort.
The findings show that the incidence of epilepsy was higher in the schizophrenia patient group at 6.99 per 1,000 person-years compared to 1.19 in the non-schizophrenia control. Incidence of schizophrenia was 3.53 per 1,000 person-years for patient with epilepsy compared to 0.46 in the non-epilepsy group. Researchers also reported that schizophrenia incidence was slightly higher in men with epilepsy than in women with the disease.
“Our research results show a strong bidirectional relation between schizophrenia and epilepsy,” said lead author I-Ching Chou, M.D., with China Medical University Hospital and Associate Professor with China Medical University in Taichung, Taiwan. “This relationship may be due to common pathogenesis in these diseases such as genetic susceptibility and environmental factors, but further investigation of the pathological mechanisms are needed.”
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Two-way relationship
Researchers in this study also found that schizophrenia levels were slightly higher in men with epilepsy than in women with the disease.
Dr I-Ching Chou, associate professor with the China Medical University in Taichung inTaiwan, said:
“Our research results show a strong bidirectional relation between schizophrenia and epilepsy.
“This relationship may be due to common pathogenesis in these diseases such as genetic susceptibility and environmental factors, but further investigation of the pathological mechanisms are needed.”
Dr Manny Bagary, consultant neuropsychiatrist in Birmingham, said it was a “very interesting” study.
“We have been aware that epilepsy sufferers seem to be have an increased risk of psychosis but this is the first convincing study to suggest that people with schizophrenia could also be at risk of developing epilepsy, suggesting a bidirectional relationship has been found between depression and epilepsy”.
“The association may be due to a common environmental factors such as traumatic brain injury or brain haemorrhage in utero. Alternatively, a genetic association may be relevant such as LGI1 or CNTNAP2 genes which have been associated with seizures and psychosis.”
Full citation: “Bidirectional Relation Between Schizophrenia and Epilepsy: A Population-Based Retrospective Cohort Study.” Yu-Tzu Chang, Pei-Chun Chen, I-Ju Tsai, Fung-Chang Sung, Zheng-Nan Chin, Huang-Tsung Kuo, Chang-Hai Tsai and I-Ching Chou. Epilepsia; Published Online: September 19, 2011 (DOI: 10.1111/j.1528-1167.2011.03268.x). http://doi.wiley.com/10.1111/j.1528-1167.2011.03268.x
Epilepsia is the leading, most authoritative source for current clinical and research results on all aspects of epilepsy. As the journal of the International League Against Epilepsy, subscribers every month will review scientific evidence and clinical methodology in: clinical neurology, neurophysiology, molecular biology, neuroimaging, neurochemistry, neurosurgery, pharmacology, neuroepidemiology, and therapeutic trials. For more information, please visit http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1528-1167.
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.
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