Epilepsy, Schizophrenia Share Close, Unexplained Relationship
For the first time, researchers have confirmed a bidirectional relationship between epilepsy and schizophrenia. Although experts have some theories to explain this close association, for now it is unexplained and requires further research.
Epilepsy/schizophrenia link needs more study
Epilepsy, a brain disorder in which individuals experience disturbed brain activity (seizures) repeatedly over time, affects about 3 million Americans of all ages and about 50 million people worldwide. In most cases, the cause of the seizures is not identifiable.
Schizophrenia is a disabling, chronic brain disorder that distorts the way a person thinks, acts, perceives reality, and relates to others. About 1.1 percent of adults (age 18 and older) in the United States have schizophrenia. Although its exact cause is not known, schizophrenia does run in families, and research shows people with schizophrenia have an imbalance of certain brain chemicals (e.g., dopamine). Newer research suggests abnormal brain structure may also be involved in some cases.
The new study, conducted by researchers from Taiwan, reported that patients with epilepsy were nearly 8 times more likely to develop schizophrenia, while individuals with schizophrenia were about 6 times more likely to develop epilepsy. The incidence of schizophrenia was slightly higher in men who had epilepsy than in women with the disease.
Researchers based their findings on data between 1999 and 2008 from the Taiwan National Health Insurance database, from which they found 5,195 patients with schizophrenia and 11,527 individuals with epilepsy diagnosed during that time span. Both groups of patients were compared to age- and sex-matched controls.
In a previous study from Johns Hopkins entitled “Schizophrenia and Epilepsy: Is There a Shared Susceptibility?” the authors suggested that “genes implicated in neurodevelopment may play a common role in both conditions,” and they speculated that “recently identified causative genes for partial complex seizures with auditory features might help explain the pathophysiology of schizophrenia.”
The Taiwan study is important because it demonstrates a strong bidirectional relationship between epilepsy and schizophrenia. According to the lead author I-Ching Chou, MD, associate professor with China Mediccal 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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Chang Y-T et al. Epilepsia 2011 Sep 19 online; doi: 10.1111/j.1528-1167.2011.03268.x
National Institute of Mental Health