Epilepsy drug exposure linked to poor school results

Researchers from the Neurology Research Group in the Swansea University Medical School found that exposure to epilepsy drugs in the womb is linked to significantly poorer school test results among seven year olds.

Swansea University reports the research, published recently online in the Journal of Neurology Neurosurgery & Psychiatry, recommends that mothers to be need to be fully informed of the risks of treatment, but these should be weighed against the need for effective seizure control during pregnancy.

Women with epilepsy who need drugs to control their seizures are currently advised to continue taking them during pregnancy because convulsions can harm both mother and the unborn child.

Several studies indicate that epilepsy drugs, particularly sodium valproate, taken during pregnancy, are associated with neurodevelopmental disorders, but few of these studies have been based on population data.

To address this, the researchers from the Neurology Research Group in Swansea University Medical School used routinely collected healthcare data from the Secure Anonymous Information Linkage (SAIL) databank and national school test (key stage 1) data to compare the academic performance of seven year olds in Wales born to mothers with epilepsy.

SAIL contains the anonymised primary care health records of 80% of Welsh family doctors, corresponding to around 77% of the Welsh population (2.3 million people).

The Key Stage 1 (KS1) test assesses maths, language (English/Welsh) and science among seven year olds, scoring them from levels 1 to 3. Test results were available for four hundred and forty children whose mothers had been diagnosed with epilepsy before their pregnancy for 2003 through to 2008.

Prescription patterns were divided into five categories; treatment with one drug (carbamazepine, lamotrigine or sodium valproate), a combination of several drugs, and no drug treatment. 54% of the thirty nine mothers prescribed several drugs were taking sodium valproate, but there were fifteen different drug combinations in all.

The results showed that children born to mothers who had been prescribed carbamazepine or lamotrigine, or nothing, performed just as well as those born to mothers of the same age and deprivation level, but without epilepsy. But those whose mothers had been prescribed sodium valproate during their pregnancy performed 10.5 -13% less well on all KS1 tests than those in the comparison group. Children born to mothers who had been prescribed a combination of epilepsy drugs achieved even worse results. Their scores were 19-22% lower. Excluding children with epilepsy and whose mothers smoked from the analysis didn’t materially change the results.

The researchers acknowledge that they weren’t able to account for certain potentially influential factors, such as the mother’s IQ, weight or alcohol consumption, the doses of epilepsy drugs prescribed, or intake of folic acid around conception. But they point out their results echo those of other independent studies.

Professor Mark Rees, Professor of Neurology and Molecular Neuroscience Research said “While this study highlights the risk of cognitive effects in the children of mothers prescribed sodium valproate or multiple [anti-epilepsy drugs], it is important to acknowledge that some epilepsies are difficult to manage without these treatment regimens.”

Dr Owen Pickrell, leader of the SAIL neurology team, said “Women with epilepsy should be informed of this risk and alternative treatment regimens should be discussed before their pregnancy with a physician that specialises in epilepsy.”

In a linked commentary of the study, Dr Richard Chin of the University of Edinburgh’s Muir Maxwell Epilepsy Centre, emphasises the importance of a study that is based on population data as this can be used to inform preventive/interventional strategies and help women to better understand the implications of epilepsy treatment while pregnant.

He said “By providing ‘functional’ outcome data from their study, the authors have now provided information that prospective parents may find readily tangible: it should be included in information given to women with epilepsy prior to pregnancy.”

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