HERE鈥橲 a surprising confession from a research scientist: I am faced with a moral dilemma. My colleagues and I are working on a cure for a serious disease that could help millions of people. Yet the results of the work could be used in other 鈥� entirely unhealthy 鈥� ways. What should we do?
For more than a decade, we have been studying the circuits in the brain that control appetite in the hope of finding a way to treat people who seriously over-eat. You may have read about the team鈥檚 recent success with a hormone called PYY 3-36: the research generated headlines around the world when it appeared in Nature a few weeks ago (vol 418, p 650). What you won鈥檛 have heard, however, is how uneasy this discovery makes me feel.
The hormone is released from the gastrointestinal tract after eating and is part of the reason you don鈥檛 feel hungry after a meal. As the substance builds up in the circulation, it crosses the blood-brain barrier and activates 鈥渋nhibitory鈥� neurons in a part of the brain鈥檚 hypothalamus called the arcuate nucleus. In effect, the hormone is the gut鈥檚 way of telling the brain to stop generating hunger pangs. Now we know that the same message can be created by administering the hormone artificially. When we injected 12 people with the hormone, they consumed one-third fewer calories than people injected with a placebo. Their reduced appetite lasted for 12 hours. If clinical trials go as well as we hope, this hormone could be on the shelves as an anti-obesity drug within four years. Eventually, our work could also lead to treatments for anorexia.
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On the one hand, this is great news. 26 per cent of people in the US are clinically obese and 20 per cent in Britain. The numbers are increasing rapidly in every country where there is adequate nutrition, including China and India, leading to premature death from heart disease, stroke, diabetes and cancer. Worse, efforts to curb obesity through education, low-calorie foods, dieting and exercise regimes simply aren鈥檛 working. Trapped between a food industry that is trying to fatten us up and a health farm industry that is trying to slim us down, we desperately need another approach.
But my area of work has implications that could alter our society in undesirable ways. Once you start to interfere with the brain circuits that control appetite, you have the potential to alter someone鈥檚 personality. You cannot turn a chubby gastronome into a thin person lacking any interest in food without changing them in other ways too. And if we can alter people鈥檚 desire for food, we can alter other deep-seated desires: the hypothalamus is also home to brain circuits that influence sex drive and sexual orientation.
Is this power desirable? We are identifying the brain鈥檚 most private secrets, but also how to control them. Will we end up with a 鈥渃haracter in a bottle鈥� scenario in which people can choose their personalities? Even if our society uses it responsibly, what鈥檚 to stop dictators or rogue cults from exploiting chemical alteration of human drives for their own ends, offering growth, sex or happiness benefits to loyal supporters and withholding them from others?
We already have drugs like Prozac that affect these circuits 鈥� and to some extent affect personality. But Prozac鈥檚 effect is relatively weak. Future drugs will be better targeted and more effective 鈥� and could overwhelmingly alter someone鈥檚 nature. Suddenly we are treating humans entirely as machines, albeit complicated ones. Perhaps in as little as ten years, neurochemical research could lead to such scenarios.It鈥檚 getting a little scary.
Why voice these concerns now? There comes a stage during any research when it becomes possible to see where it may lead. There鈥檚 another later stage at which it becomes obvious to everyone where it is leading, but it is far better to make decisions about research if you can tackle it at the earlier stage. To do that, it takes people who have been in the game for a while. I have been working on neuropeptides since 1975, and when I look back over the years I can see how far we鈥檝e moved forward, and how things might go.
So what should a researcher do? Close their eyes and run blindly forwards? I believe you cannot stop progress 鈥� although I am sure that the scientists who put together the first atom bomb thought much the same. Is it possible to cure these diseases without altering the circuits in the brain to some degree? I don鈥檛 believe it is. So that inevitably raises the danger that someone else will use the knowledge we gain about brain circuitry and manufacture drugs that go the whole way and induce a genuine change of character.
In the meantime, I believe a scientist has a clear duty to inform people of the direction their research is going so that they can have an informed opinion. If a strand of research has a small advantage but a big risk, society may declare that it doesn鈥檛 want to go with it. If it is not the job of scientists to make ethical decisions about their work, it is certainly their job to tell others where it is leading. We do not want to be credited with a societal tragedy on the level of the atom bomb.