Published on: June 13, 2014
by Sarah Knapton for The Telegraph:
A drug to prevent the devastating memory loss associated with Alzheimer’s disease is a step closer after scientists discovered the secret behind why people with dementia cannot form new memories.
It was previously thought that Alzheimer’s was primarily caused by the build up of sticky amyloid plaques in the brain which stop neurons from firing. But drugs to clear the plaques have so far failed to bring any improvement to sufferers.
Many scientists believe that the amyloid plaques trigger a ‘cascade effect’ of other symptoms meaning that by the time they are spotted it is already too late.
Researchers at Penn State University have now discovered that those plaques may be triggering overproduction of a chemical that drives memory loss by preventing a key part of the brain from functioning.
They believe a drug which targets the chemical – known as GABA neurotransmitter – to prevent it from acting could halt memory loss in sufferers.
“Billions of dollars were invested in years of research leading up to the clinical trials of those Alzheimer’s drugs, but they failed the test after they unexpectedly worsened the patients’ symptoms,” said Professor Gong Chen, a biologist who led the work at Penn State University.
“The research behind those drugs had targeted the long-recognised feature of Alzheimer’s brains: the sticky build-up of the amyloid protein known as plaques, which can cause neurons in the brain to die.
“The research of our lab and others now has focused on finding new drug targets and on developing new approaches for diagnosing and treating Alzheimer’s disease.”
Chen’s team found that the GABA neurotransmitter was drastically increased in the deformed versions of the normally large, star-shaped “astrocyte” cells which, in a healthy individual, surround and support individual neurons in the brain.
Those deformed cells were found in the dentate gyrus, a gateway to hippocampus area of the brain that is critical for learning and memory.
The team found that in mice with too much GAMA neurotransmitter the neurons in the dentate gyrus are not fired up like they normally would be when a healthy person is learning something new or remembering something already learned.
“We recently discovered an abnormally high concentration of one inhibitory neurotransmitter in the brains of deceased Alzheimer’s patients,” said Chen.
“After we inhibited the (chemical) in the brains of the mice, we found that they showed better memory capability than the control mice with Alzheimer’s disease.
“We are very excited and encouraged by this result, because it might explain why previous clinical trials failed by targeting amyloid plaques alone.
“An ultimate successful therapy may be a cocktail of compounds acting on several drug targets simultaneously.”
The discovery also has potential for the development of a new test for Alzheimer’s disease, which is the most common form of dementia and one for which no cure has yet been found.
The research was published in Nature Communications.
Older people who report greater levels of social engagement have more robust gray matter in regions of the brain relevant in dementia, according to new research led by scientists at the University of Pittsburgh Graduate School of...
In a new study, University of Nebraska–Lincoln sociologist Marc A. Garcia explored how educational attainment can benefit cognitive health in later life, and whether there are differences in its benefits among minorities. Garcia and his co-authors...
A genetic variation in some people may be associated with cognitive decline that can’t be explained by deposits of two key proteins associated with Alzheimer’s disease, amyloid β and tau, according to a study...
The material presented through the Think Tank feature on this website is in no way intended to replace professional medical care or attention by a qualified practitioner. WBHI strongly advises all questioners and viewers using this feature with health problems to consult a qualified physician, especially before starting any treatment. The materials provided on this website cannot and should not be used as a basis for diagnosis or choice of treatment. The materials are not exhaustive and cannot always respect all the most recent research in all areas of medicine.