Migraine - Future prospects

To identify other brain areas involved in migraine that could provide additional drug targets, non-invasive imaging studies can be done of people while they are having a migraine.

An illustration of how migraine sufferers feel [JayaDeva].

With this information, researchers are designing new animal models in which to test drugs that might reduce artificially produced activity in these newly identified brain areas. Hopefully, after these drugs have undergone safety tests in animals, they can be tried out as anti-migraine drugs in people.

For acute migraine therapy, BIBN 4096 BS, a molecule that blocks the activity of a neuropeptide called CGRP is looking very hopeful. Experiments in animals have shown that CGRP is one of the chemical messengers released by the trigeminal nerve when it is stimulated that causes brain blood vessels to expand. Triptans work, at least in part, by preventing CGRP release from nerve endings but, triptans have some unwanted effects on blood vessels outside the brain, which can be dangerous for people with heart disease So if the effects of CGRP could be prevented in some other way, the result might be a migraine treatment with fewer side effects. BIBN 4096 BS blocks CGRP activity in the brain blood vessels of animals and has recently been successfully tested in migraine patients.

The study of migraine genetics is providing other potential leads for new treatments. There is a rare form of migraine (familial hemiplegic migraine) in which two genes are mutated. The proteins encoded by these genes are involved in the transmission of messages between nerves It is not known whether similar mutations are involved in the common forms of migraine but if they are, these proteins might be targets for new anti-migraine drugs. To investigate this possibility, researchers have introduced one of the gene mutations into mice. These genetically modified mice have changes in their brain behaviour that make them an excellent model in which to study migraine mechanisms and potential treatments.

For migraine prevention, there are also some hopeful leads, in particular the anti-epileptic drugs. Patients taking the new anti-epileptic topiramate noticed improvements in their headaches. Clinical trials have subsequently shown that topiramate reduces migraine frequency and it is now licensed for prevention of migraines. No additional animal experimentation was needed to extend topiramate's licence, because its safety had already been evaluated. Nevertheless, researchers are now trying to find out how topiramate achieves its effects by carrying out experiments in animals. The results of these experiments might make it possible to design completely new drugs that will be even better at preventing migraine than topiramate.

Feverfew contains a molecule that may lead to a new treatment for migraine.

Feverfew, an alternative remedy for migraine, is also being investigated as a preventive in clinical trials. Herbal potions can be problematic because they often contain several active compounds -some harmful and some beneficial - and the ratio of these varies from batch to batch. However, experiments in animals are beginning to provide clues about how parthenolide, the active constituent of feverfew, has its effects and at the same time they are revealing additional potential drug targets.

Finally, the toxin from a bacterium called Clostridium botulinum is attracting some attention as a possible way to prevent migraines. People receiving injections of "botox" for cosmetic facial surgery have reported a reduction of headaches and consequently clinical trials of botox injections have been started. However, the jury is still out on whether this approach will be useful in migraine or whether it is safe to use in this disorder.

Role of animals