QBI’s Dr Jana Vukovic said the work was aimed at understanding the molecular mechanism that may impair learning and memory in the ageing population.
“Ageing slows the production of new nerve cells, reducing the brain’s ability to form new memories,” said Dr Vokovic, who performed the work in the laboratory of Professor Perry Bartlett, the Director of QBI at The University of Queensland.
“But our research shows for the first time that the brain cells usually responsible for mediating immunity, microglia, have an inhibitory effect on memory during ageing.
“Furthermore, they have shown that a molecule produced by nerve cells, fractalkine, can reverse this process and stimulate stem cells to produce new neurons.”
The discovery, published in The Journal of Neuroscience today, came after QBI scientists observed that the increased production of new neurons in mice that were actively running was due to the release of fractalkine in the hippocampus – the brain structure responsible for specific types of learning and memory.
Professor Bartlett said it had been known for some time that exercise increased the production of new nerve cells in the hippocampus in young and even aged mice.
“But this study found that it is fractalkine that appears to be specifically mediating this effect by making the microglia produce factors that activate the stem cells that produce new nerve cells,” he said.
“Once the cells are activated they divide and produce new cells, which underpin the animal’s ability to learn and form memories.
“This means that fractalkine may form the basis for the development of future therapies.
“The discovery is especially exciting because we have found that older animals suffering cognitive decline showed significantly lower levels of fractalkine.
“We are seeking ways of increasing fractalkine levels in patients with cognitive decline, and hoping this may be a new frontline therapy in treating dementia.”
Dr Vukovic said that until relatively recently, it was thought the adult brain was incapable of generating new neurons.
“But work from Professor Bartlett’s laboratory over the past 20 years has demonstrated that the brains of adult animals, including humans, retain the ability to make new nerve cells,” she said.
“The challenge is to find out how to stimulate this production in the aged animal and human where production has slowed.”
The latest work was a significant step toward achieving this goal, she said.
The article published today is titled Microglia modulate hippocampal neural precursor activity in response to exercise and aging. Its authors are Jana Vukovic, Michael J. Colditz, Daniel G. Blackmore, Marc J. Ruitenberg, Perry F. Bartlett
Media contact: Mikaeli Costello, Queensland Brain Institute, ph +61 (0) 401 580 685
firstname.lastname@example.org. Copies of the article can be supplied.
Queensland Brain Institute http://www.qbi.uq.edu.au/
The Queensland Brain Institute (QBI) was established as a research institute of The University of Queensland in 2003. The Institute operates from a $63 million state-of-the-art facility and houses 33 principal investigators with strong international reputations. QBI is one of the largest neuroscience institutes in the world dedicated to understanding the mechanisms underlying brain function.
Dementia is a devastating illness, causing grief for both sufferers and their families and for society as a whole.
Almost 280,000 Australians currently live with the illness – a figure which is set to rise to almost one million people by 2050, according to Alzheimer’s Australia.
This will cost the community about $83 billion, or 11 percent of the nation’s health care budget by 2060, without a significant medical breakthrough.
Dementia is a broad term to describe a loss of memory, intellect, rationality, social skills and physical functioning, with Alzheimer’s disease the most common form of the illness, accounting for between 50-70 percent of all dementia cases in Australia.
It is the third leading cause of death in Australia after heart disease and stroke, with one in four people over 85 suffering from the condition.
There is no known cure.
It’s estimated that healthy human brains contain about 100 billion neurons with each neuron connected to 1000 other neurons, resulting in a vast and complex network crucial to the brain’s processing capability.
However, in people with dementia, their neurons switch off and die, meaning the brain does not function as well as it should with the sufferer having problems thinking, remembering and carrying on with daily living.
According to the UK Parliamentary Office of Science and Technology, an Alzheimer’s brain at death may have lost up to 50 per cent of its weight.