Alzheimer's and CJD 'similar'

Rogue proteins are thought to cause degenerative brain disorders

Scientists have discovered striking similarities between Alzheimer's disease and the human form of mad cow disease, vCJD.

They believe the breakthrough could lead to drugs to treat both conditions.

Both are marked by a gradual and ultimately fatal deterioration of the brain and both are associated with rogue proteins.

Now Professor Chi Ming Yang, of Nankai University in Tianjin, China, has discovered that these proteins have very similar structures.

This could mean that the molecular mechanism underlying Alzheimer's disease and vCJD is the same.

Professor Yang used a computer model to map the prion protein associated with vCJD and the amyloid precursor protein associated with early stage Alzheimer's.

He found that the two proteins had a similar pattern of component parts known as amino acids.

Each are made up of a reductive amino acid followed by three non-reductive amino acids.

Reductive amino acids are more prone to damage by free radicals - charged oxygen particles that can disrupt the DNA of the body's cells.

Normally, the body can clear itself of free radicals. But with age, this system may fail.

When enough free radicals accumulate to damage a protein molecule it can malfunction.

Scientists believe this mechanism may lead to Alzheimer's, the most common cause of dementia, affecting an estimated 12 million people worldwide.

The disease is characterised by include messy "tangles" of nerve fibres and "plaques" rich in the amyloid proteins.

CJD is the human version of bovine spongiform encephalitis (BSE or mad cow disease).

It occurs naturally in about one in a million people but a new version, vCJD, has been linked with eating BSE-infected meat.

BSE and vCJD are believed to be caused by prion proteins that do not fold normally.