Researchers at the Babraham Institute near Cambridge, supported by the Alzheimer's Research Trust and the Biotechnology and Biological Sciences Research Council (BBSRC), have discovered that the brain's circuitry survives longer than previously thought in diseases of ageing such as Alzheimer's disease. The findings were published today in the journal Brain.
Alzheimer's disease causes nerve cells in the brain to die, resulting in problems with memory, speech and understanding. Little is known about how the nerve cells die, but this new research has revealed how they first lose the ability to communicate with each other, before deteriorating further.
"We've all experienced how useless a computer is without broadband. The same is true for a nerve cell (neuron) in the brain whose wiring (axons and dendrites) has been lost or damaged," explained Dr Michael Coleman the project's lead researcher. "Once the routes of communication are permanently down, the neuron will never again contribute to learning and memory, because these 'wires' do not re-grow in the human brain."
But axons and dendrites are much more than inert fibre-optic wires. They are homes to the world's smallest transport tracks. Every one of our hundred billion nerve cells continuously shuttles hundreds of proteins and intracellular packages out along its axons and dendrites, and back again, during every minute of every day. Without this process, the wires cannot be maintained and the nervous system will cease to function within a few hours.
During healthy ageing this miniature transport system undergoes a steady decline, but the challenges are immense. Axons up a metre long have to survive and function for at least eight or nine decades. Over this period, our homes will need rewiring several times, but in our brains the wires are all original, surviving from childhood. In Alzheimer's disease, axons swell dramatically, ballooning to 10 or 20 times their normal diameter. These swellings disrupt transport but not, it seems, completely. Enough material gets through the swellings to keep more distant parts of the axon alive for at least several months, and probably for a year or more. This is important because it suggests a successful therapy applied during this early period may not only halt the symptoms, but allow a degree of functional recovery.
"We've been able to look at whole nerve cells affected by Alzheimer's", said Dr Michael Coleman. "For the first time we have shown that supporting parts of nerve cells are alive, and we can now learn how to intervene to recover connections. This is very important for treatment because in normal adult life, nerve cell connections constantly disappear and reform, but can only do so if the supporting parts of the cell remain. Our results suggest a time window in which damaged connections between brain cells could recover under the right conditions."
This basic research gives hope over the longer term to the 700,000 people in the UK who live with dementia. Understanding how the brain responds to disease also tells us a lot about how it functions in all of us.
Dr Claire Cockcroft
Deputy, Corporate Affairs
The Babraham Institute
Babraham Research Campus
Cambridge CB22 3AT
Tel: +44 (0)1223 496260/ 496206
Mob: +44 (0)7786 335978
Fax: +44 (0)1223 496002
Dr Michael Coleman
Tel: +44 (0)1223 496315
Notes to Editors:
The paper "Severely dystrophic axons at amyloid plaques remain continuous and connected to viable cell bodies" is published in the journal Brain today.
The Babraham Institute is a charitable organisation devoted to biomedical research which is sponsored by the Biotechnology and Biological Sciences Research Council (BBSRC). The Institute's research is focused on understanding the biological events that underlie the normal functions of cells and on how their failure or abnormality may lead to disease. As such, Institute scientists are striving to find cures for conditions where there is currently no treatment or where the existing treatment is not fully effective or causes serious side effects. The latest technologies are being used to study the basis of conditions such as neurodegenerative disorders, birth defects, cancer and diseases of the immune and cardiovascular systems. The commercialisation of the Institute's research is managed by its trading subsidiary, Babraham Bioscience Technologies (BBT) Ltd. The Babraham Research Campus is located six miles south-east of Cambridge. Website: www.babraham.ac.uk
The Alzheimer's Research Trust provides free information on Alzheimer's disease and related dementias: phone 01223 843899 or visit www.alzheimers-research.org.uk. The charity relies solely on public donations to fund its research. Dementia research is severely under-funded - only £11 is spent on UK Alzheimer's research annually per patient, compared to £289 for people with cancer. Care services for dementia costs the UK more than cancer, heart disease and stroke combined. Alzheimer's is the most common form of dementia, which affects nearly 700,000 people in the UK, a number forecast to double within a generation. Currently there is no cure for the disease. For further information or to speak to someone able to talk about their personal experience of dementia, please contact the charity's Press Officer, Alison Cranage on 01223 843304 or email firstname.lastname@example.org