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14-03-2012 | Psychology | Article

Epilepsy linked to increased risk for psychosis


Free abstract

MedWire News: People with epilepsy are significantly more likely to experience psychosis than the general population, research confirms.

"There is considerable evidence that epilepsy patients are at increased risk of developing a psychotic illness. In particular, the evidence suggests that schizophrenia and schizophrenia-like-psychosis are associated with epilepsy," observe Mary Clarke (Royal College of Surgeons in Ireland, Dublin) and team.

"However, the majority of studies to date that have examined the association between epilepsy and psychotic illness have been mainly clinical studies that have suffered from selection bias and small sample sizes," they add.

Furthermore, the researchers say that "it is not known whether epilepsy and psychotic illness cluster within families."

To investigate further, the researchers used data from Finnish national registers for the period 1947-1990 to study 9653 families and 23,404 offspring.

The Hospital Discharge Register (HDR) was used to assess psychiatric and neurologic outcomes in adulthood among the offspring, and linkage of the HDR and the Finnish Population Register was used to assess parental history of psychosis and epilepsy.

The researchers found that, overall, individuals with epilepsy (n=208) were 5.5 times more likely to have any psychotic disorder, 6.5 times more likely to have bipolar disorder, and 8.5 times more likely to have schizophrenia compared with nonepileptic individuals.

The team also found that individuals with a parental history of psychosis had a 2.7-fold increased risk for epilepsy compared with those without such a parental history. This increased risk was not due to a comorbid diagnosis of epilepsy in the parents, the researchers note.

Similarly, individuals with a parental history of epilepsy had a 2.0-fold increased risk for psychosis compared with those without epileptic mothers or fathers. Again, this increased risk was not driven by comorbid psychosis in the parents.

Clarke and team conclude in Biological Psychiatry: "These findings support recent evidence of overlapping etiological factors between epilepsy and schizophrenia, especially recent evidence of a genetic overlap between these disorders."

By Mark Cowen

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