Scientists have hailed a new drug for Alzheimer's disease after a trial successfully halted the mental decline associated with the condition for a period of three years.
Researchers found that patients who had injections every two weeks of the drug immunoglobulin, made from antibodies in human blood, showed no decline in cognition, memory, daily functioning or mood.
Immunoglobulin is normally given to patients who suffer from an immune deficiency, but it has also been found to protect the brains of those with early stage Alzheimer's. Each dose is extracted from the plasma of 1,000 blood donors.
Professor Clive Ballard, director of research at the Alzheimer's Society, said: "This is probably the most exciting drug we know about that is currently in the late stages of research.
"We now know it is safe but the real test will be whether these initial promising results can subsequently be replicated in larger groups."
Just 24 patients were tested with the drug in the study, who were given varying doses of the drug over different periods. A larger study is now underway. Professor Ballard added: "If the phase 3 trials are successful, and it can be made cost effective, this drug could be on the shelves within 10 years."
He added: "One in three people over 65 will develop dementia. While finding a cure is the Holy Grail of dementia research, it is also vitally important that we continue to fund studies like this if we are to develop more treatments to help people to live well with the condition."
However, the difficulty of producing immunoglobulin means it is not cheap, costing thousands of pounds per patient. The findings were presented at the Alzheimer's Association International Conference in Vancouver, Canada, yesterday.
There are currently three licensed drugs for the prevention of Alzheimers in the early and moderate stages but they are of limited effectiveness, slowing the progression of the disease in some patients but not in others.
Researchers studying immunoglobulin had previously reported its beneficial effects up to 18 months but have now extended the treatment for a further 18 months and found no decline in cognition and memory.
Scientists have been experimenting with immunotherapy – treatments to stimulate the immune system in Alzheimers patients – for several years but this is the first that has been shown to be both effective and safe.
The drug is thought to work by targeting the beta-amyloid protein, sweeping up and removing small fragments that form the amyloid plaques in the brain that lie behind the degenerative disease.
Normal Relkin, of Weill Cornell Medical College, New York, said: "This is the first study to report long-term stabilisation of Alzheimer's symptoms with intravenous immunoglobulin. While the small number of participants may limit the reliability of our findings , we are very enthusiastic about the results."
Early findings from the trial showed rates of brain shrinkage typical of Alzheimer's were halved in patients treated with the drug, as measured on MRI scans.