Healthy Skepticism Library item: 2199

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Publication type: news

Talan J.
Study: Epilepsy research focus wrong
Newsday 2005 Aug 17
http://www.newsday.com/news/printedition/health/ny-hsepilepsy174386754aug17,0,3629964.story?coll=ny-health-print

Keywords:
epilepsy astrocytes brain neuroscience

Notes:

Ralph Faggotter’s Comments: The thrust of this article is that it may be astrocytes rather than neurones which trigger epileptic seizures.The problem is, that even if this turns out to be true, the assumption that this will lead to improved anti-epileptic drugs is based on the misconception that new drugs are generally developed from first principles, whereas the reality is that the process generally works in reverse, which is not nearly as clever. That is, a drug is found, by trial and error (or by accident) to work, then the reason why it works can sometimes be determined retrospectively. This (sadly less impressive) reality helps to explain why there have been so few genuinely new useful drugs developed in the last 25 years in spite of a massive explosive increase in our knowledge of how biological processes work.

Full text:

Study: Epilepsy research focus wrong

BY JAMIE TALAN
STAFF WRITER

August 17, 2005

Epilepsy researchers may have spent decades studying and treating the wrong population of brain cells, and consequently drug companies may have to start developing new medicines to treat the disease, according to a new study.

While most researchers have targeted neurons, the study suggests that it is the brain’s abundant support cells – the astrocytes – that are the key to epilepsy, which affects about 2 million Americans.

Dr. Maiken Nedergaard, a professor of neuroscience at the University of Rochester Medical Center, said it took modern laboratory techniques to make this surprising finding, published this week in Nature Medicine. She added that it could take years for the findings to gain acceptance.

“No one wants to hear that the cells they have been studying for decades are not the cause of epilepsy,” Nedergaard said. “It will take time and a lot more proof for researchers to accept this.”

Nedergaard and her colleagues say that the seizures are caused by an abnormal response in the brain’s astrocytes. These support cells have largely been ignored in common human diseases, even though they are 10 times more abundant than neurons.

A growing number of researchers are finding that these cells could have a major role in brain diseases like Parkinson’s and Alzheimer’s.

But Nedergaard was sure these cells had secrets they weren’t giving up. The scientists blocked nerve cell function in animals prone to seizures. Presumably, this would have prevented seizures, but it didn’t. Nedergaard’s group found that the astrocytes were the first player on the scene, making a chemical called glutamate that trips a cascade of abnormal electrical signals, leading to seizures.

“When neurons abnormally fire, it is a symptom, not the cause,” she said.

It’s been known that astrocytes swell, but it was always considered a secondary event after a seizure.

“This opens a door to new treatments,” Nedergaard said. It has long been thought that anti-epileptic drugs target the synapse – the gap between neurons that allows one cell to send messages to the next cell. Quieting the synapse, drug developers thought, prevented abnormal firing of neurons.

But this new study also found that the anti-epileptic medicines also slow down astrocyte activity, which explains why medicines work in two of every three patients.

Nedergaard said the next generation of medicines could have a more direct effect on seizure activity.

“It provides hope,” she added. “We can design new drugs that target astrocytes,” whose main function is to keep a neuron’s environment healthy.

“The potential role of astrocytes in the generation of epilepsy has been largely ignored,” added Dr. Michael Berg, medical director of Rochester’s Strong Epilepsy Center.