Scientists have taking a large step in the search for a medicine that could beat Alzheimer's disease, after a drug-like compound was used to halt brain cell death in mice for the first time.
Although the prospect of a pill for Alzheimer's remains a long way off, a recent British study provides a major parting of the seas for future drug treatments. The compound works by blocking a faulty signal in the brain that is affected by neurodegenerative diseases, which shuts down the production of essential proteins, leading to brain cells being unprotected and dying off.
|A Computer image of the brain of an Alzheimer's patient |
(credit: Science photo library)
It was tested in mice with prion disease - the best animal model of human brain degeneration. Scientists say they are confident the same principles would apply in a human brain with regard to diseases such as Alzheimer's or Parkinson's.
The study was carried out at the Medical Research Council's (MRC) Toxicology Unit at the University of Leicester and published in early October of 2013 in the journal Science Translational Medicine.
“It's a real step forward,” team leader Professor Giovanna Mallucci told The Independent. “It's the first time a substance has been given to mice that prevents brain disease. The fact that this is a compound that can be given orally, that gets into the brain and prevents brain disease, is a first in itself… We can go forward and develop better molecules and I can't see why preventing this process should only be restricted to mice. I think this probably will translate into other mammalian brains.”
In devastating brain diseases like Alzheimer's, the production of new proteins in the brain is turned off by a build-up of misfolded proteins called "amyloids". This build-up leads to an over-activation of our brains natural defense mechanism that stops other essential proteins from being produced. Without these proteins to protect us, the brain cells die off slowly on their own, leading to the progression of the disease and eventually presenting symptoms.
The compound used in the study works by inhibiting an enzyme, known as PERK, which plays a key role in activating this defense mechanism. In mice with prion's disease, it restored proteins to protect brain cells “stopping the disease in its tracks”. Over time, it actually began to alleviate symptoms and reduce memory loss.
Unfortunately the compound also produced significant side effects in the mice, including weight loss and mild diabetes. Professor Mallucci said it would “not be impossible” to develop a drug that protected the brain without the side effects and that work towards doing so has been “very promising”.
The breakthrough has been very well accepted by neurologists, although some caution that although this may be significant proof of principle and a possible basis for new treatments, it does not guarantee an cure for Alzheimer's will be revealed in the near future.
Professor Roger Morris, acting head King's College London's department of chemistry, said: “This is the first convincing report that a small drug, of the type most conveniently turned into medicines, stops the progressive death of neurons in the brain as found, for instance, in Alzheimer's disease. True, this study has been done in mice, not man; and it is prion disease, not Alzheimer's, that has been cured. However, there is considerable evidence that the way neurons die in both diseases is similar; and lessons learned in mice from prion disease have proved accurate guides to attenuate the progress of Alzheimer's disease in patients.”
“From finding the first effective drug in a mouse, to having an effective medicine in man, usually takes decades to bring to fruition, in the very few cases in which it is successful. So, a cure for Alzheimer's is not just around the corner. However, the critical point of principle made by Professor Mallucci's study is that a drug, given orally, can arrest neurodegeneration caused by amyloid in the brain. This finding, I suspect, will be judged by history as a turning point in the search for medicines to control and prevent Alzheimer's disease.“
David Allsopp, professor of neuroscience at Lancaster University said that the study had thrown up ”very dramatic and highly encouraging results“, but said that more research was needed to overcome the "problematic side-effects" and to prove itself as a realistic treatment against diseases like Alzheimer's and Parkinson's.
According to the Alzheimer's Association, there are more than 5 million people in the U.S. who have Alzheimer's disease today. In fact, it is listed as the 6th leading cause of death. In 2013, Alzheimer's will cost the nation $203 billion. This number is expected to rise to $1.2 trillion by 2050.