Behavioural effects of the newer antiepileptic drugs: an update

The negative and positive effects of the nine newer antiepileptic drugs that have received a product licence in the UK or in the US are reviewed. The importance of avoiding misinterpretation of the data because of confounding factors such as alternative psychosis, the release phenomenon or drug interactions is emphasised. Vigabatrin has been associated with both psychosis and depression. Due to the concentric visual field defects that may occur with vigabatrin, its use is now limited, although it remains the drug of choice for infantile spasms. Lamotrigine seems to be largely associated with improvement rather than deterioration of mood and behaviour. It may have a role in treating affective disorder. Gabapentin probably has relatively little effect on behaviour but may exacerbate behavioural problems in some children with pre-existing difficulties. Topiramate may precipitate both psychosis and depression, but these are less likely to occur if the currently recommended lower starting doses, escalation rates and target doses are used. The data for tiagabine are limited, but there is no clear evidence for psychosis or depression being caused by this drug. Oxcarbazepine may be of value in treating mood disorder, but the information is very limited. There are few reports of behavioural disturbances with levetiracetam, but the data suggest that there is no significant increase in psychosis or depression. There are some reports of psychosis and other behavioural disturbances with felbamate, but the use of this drug is limited by the serious adverse effects of hepatotoxicity and aplastic anaemia. There is some evidence for psychosis with zonisamide, but there is also a suggestion that this drug may be of benefit in treating psychiatric disorders. Careful individual assessment of each patient should enable the clinician to determine whether the medication or some other factor is responsible for any behavioural disturbance.