The West's only human brain bank is suffering from a severe shortage of "normal" brains.

The Bristol-based bank currently has 800 brains, many of which were donated by people with Alzheimer's, but scientists are now appealing for more adults to bequeath their grey matter.

The lack of normal human brains is hampering the hunt for a dementia cure.

Professor Seth Love, who works at the South West Brain Bank in Frenchay Hospital, says the majority of drugs already developed for brain-related diseases have relied on research on human brains.

He said: "Every medication you can think of for treating chronic diseases of the nervous system has been developed from looking at brain tissue. From the most common Parkinson's drug, to the latest Alzheimer's drugs and also drugs for Multiple Sclerosis.

"We can't predict what we will discover from looking at brain tissue but I don't think there is any substitute for looking at the real thing.

"And we can't be certain that what we're looking at in brain tissue from someone with Alzheimer's disease is abnormal unless we have the opportunity to compare it with a normal brain from someone of the same age."

The brain is taken within 72 hours of death, cut in half and preserved for further research. It leaves no obvious marks and should not hold up any funeral preparations.

All of the brains stored in the brain bank have been sampled and the results catalogued for future reference.

"We have hugely generous donations from relatives where people have been suffering with dementia. They are aware of the disease so are highly motivated," Prof Love said.

"If someone drops down at the age of 70 from a heart attack, the last thing they think of is giving the brain for research. There's a shortage of normal brains because people just haven't been thinking about it, it doesn't even cross their mind."

The appeal comes as Prof Love and his team, the Bristol Dementia Research Group, are awarded £340,000 for their research into dementia and Alzheimer's disease.

The Alzheimer's Research Trust grant, combined with money from local charity BRACE, will pay for a new state-of-the-art microscope with which to look at healthy and diseased brain tissue brain tissue. However, without any more donations it will not be able to be used to its full impact.

There are currently more than 700,000 people in the UK with dementia, 4,000 of which live in Bristol.

In 2005, scientists searching for a cure for Parkinson's disease launched a similar appeal for human brains. Scores of people stepped forward to promise their brains as a result, including London Mayor Boris Johnson's sister Rachel Johnson.

Donations to the South West Brain bank, which was established in the early 90's, are accepted from people across the region and beyond.

For informal queries on how to make a donation or to request further information on what is involved, please call Miss Laura Palmer at the South West Brain Bank on 0117 970 1212 ext 2270.