One goal in modern medicine is to use genetics to determine the best treatment strategy for an individual patient. A simple, cheap genetic test which predicts response to a particular treatment has clear utility for patients.

To date, psychiatry has lagged behind general medicine, no doubt due to the complexity of CNS tissue and the sheer number of components involved in CNS processing, but the picture is changing. One particular area of interest is the treatment of alcohol dependence.

The pharmacogenomics of topiramate

The drug topiramate started off as an anticonvulsant, but was also been found to be effective in reducing alcohol consumption in heavy drinkers. An American study has advanced our knowledge. Natural variation in the DNA coding for a type of glutamate receptor called the kainite receptor was shown to determine if problem drinkers responded to topiramate treatment.

In those carrying the CC variant at rs2832407, topiramate (200mg/d) markedly reduced the number of heavy drinking days compared to placebo (Fig. 1). Heavy drinking decreased from 5 days per week to approximately 1 day per week in CC subjects treated with topiramate.

In a 12 week study, heavy drinkers with the CC genotype at rs2832407 in the kainite receptor showed significant reductions in heavy drinking when treated with topiramate.

Definite study

A larger study is now underway, hoping to confirm the initial genetic findings. If the result is replicated, genetic testing may translate to routine clinical practice for heavy drinkers considering topiramate treatment.

This would represent a significant advance in the management of alcohol disorders.