brain

Two Alzheimer’s drugs show promise

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(This story was #18 in Discover magazine’s top 100 stories of 2008.)

Two unconventional treatments for Alzheimer’s disease show promising early results. Both Rember (methylthioninium chloride) and Dimebon (dimebolin hydrochloride) appear to slow the mental decline associated with the illness.

No effective medicines exist for Alzheimer’s, which is estimated to afflict more than 4 million people in the United States alone. The disease is characterized by a decline in cognition and function and usually strikes after age 60. Most Alzheimer’s treatments have targeted amyloid, the main protein component of the associated plaques that form in the brain; Rember is the first to target the tangled, abnormal fibers of a protein called tau. At an Alzheimer’s conference in Chicago, the drug, made by TauRx Therapeutics, was reported to slow the progress of mild to moderate Alzheimer’s disease by 81 percent over the course of a year. In a phase 2 trial of 321 people with mild to moderate disease, those on the drug stayed at about the same cognitive level for up to 19 months, while those on the placebo got worse. A final trial is expected to begin in 2009.

The second drug, Dimebon, is an allergy drug used in Russia 20 years ago. A Lancet article in July reported that over 26 weeks of treatment, Dimebon significantly improved memory, thinking, and overall functioning in 68 Alzheimer’s patients, compared with a 66-member control group. Although researchers don’t know exactly how Dimebon does this, it may work by protecting mitochondria—the powerhouses of cells—from injury, says Rachelle Doody, the study’s lead author and a neurology professor at Baylor College of Medicine in Houston. A phase 3 trial for the drug began recruiting participants in June.

Actions speak louder than images

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(This article appeared in the 7 December, 2006 issue of Nature.)

Handle with care: can brain scans really identify antisocial people?

Can brain scans of a racist, liar or psychopath accurately tell whether that person will persecute, fib or kill? No, say experts in the ethics of neuroscience, who are increasingly concerned that such images will be used to make dangerous legal or social judgements about people’s behaviour. They say it is time for scientists, lawyers and philosophers to speak up about the limitations of such techniques.

“Lawyers want to know ‘Can I put somebody on the scanner and tell if they’re racist?’” says Elizabeth Phelps, a psychologist and neuroscientist at New York University who has studied the brain’s response to race. “We as 
a group of scientists have to be 
able to say that we can’t make that distinction.” Phelps spoke at a panel discussion on the emerging field of neuroethics held in New York last week.

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Visual neuroscience: Look and learn

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(For me, this story, published May 2006, had the perfect blend of basic neuroscience, public health implications and human interest. You can download a pdf of this article.)

Prevailing wisdom says the adult brain cannot learn to see if it had no visual stimulation during childhood, but blind people in India seem to be breaking all the rules.

After 29 years of being officially blind, SK is learning to see — and defying neuroscience in the process.

Doctors gave SK his first pair of glasses in July 2004. He had been too poor to afford a pair before — but then he was a 29-year-old blind man, what use were glasses to him? Had he been given glasses as a child they might have helped him overcome his congenital aphakia — an extremely rare condition in which the eyeball develops without a lens. Yet his chances of being diagnosed, let alone treated, in the poor Indian village in which he was born were slim. As a result, SK was living in a ‘hostel for the blind’ with no running water when the doctors arrived from New Delhi.

SK’s doctors weren’t sure how much sight he would gain, or if he would comprehend what he saw. For the first year, he had only the most basic visual skills. He could recognize simple two-dimensional objects but anything three- dimensional, even an everyday object such as a ball, was beyond him. All this was consistent with the idea of a ‘critical period’ in vision: that if you haven’t learned to see by a certain age, you never will.

But 18 months after getting his glasses, SK surprised everyone. He had begun to make sense of his world, building his visual vocabulary through experience and recognizing more complex objects with varying colours and brightness. In doing so, he turned one of the most fundamental concepts in neuroscience on its head.

“Twenty-nine years without any normal vision? I would have said that’s a life sentence,” says Ron Kalil, a visual neuroscientist at the University of Wisconsin in Madison. For Kalil and other experts, the impossible now seems possible. And while the scientists might be amazed by the brain’s adaptability, the real winners are the countless blind people — both children and adults — who had been considered untreatable.

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