Researchers are testing the potency of a vaccine to destroy “toxic tangles”, which are a hallmark of the disease.
Trials involving patients with early stages of the incurable condition are already under way.
If successful they could pave the way for a simple jab that nullifies the effects of the devastating disease.
Experts think they have developed a therapy that targets the destructive tangles in brains of people with the disease.
The inoculation works by stimulating the body’s immune system to attack an abnormal form of protein which prevents nutrients and essential supplies moving through cells.
Scientists hope the vaccine, called ACI-35, will halt the progression of Alzheimer’s in patients who receive it early enough.
The breakthrough medication is being tested at the Research Institute for the Care of Older People (RICE) at the Royal United Hospital, Bath.
Professor Roy Jones, director of RICE, said: “This is very important. It opens the way to a completely different and hopefully much more effective vaccine.”
Alzheimer’s is the most common cause of dementia, playing havoc with memory, thinking and behaviour.
Many experts think its cause is related to the tau protein, critical in ensuring that nerve cells in brains function properly.
In people with Alzheimer’s it gets tangled, disrupting nerve cells and gradually killing them.
The vaccine should produce antibodies against tangled tau and stop the disease progressing.
The study involves patients aged 60-85 with mild to moderate Alzheimer’s.
Medication is given two, three or five times in six months, plus a booster injection after six or 16 months.
Tests are taking place in Bath, the Royal Liverpool University Hospital, St George’s Hospital in London and Royal Infirmary of Edinburgh until June next year.
Dr James Pickett, of the Alzheimer’s Society, said: “This is targeted at tau protein tangles that may be linked with memory loss.
“With an ageing population and no new dementia drugs in over a decade the need to find new treatments is more urgent than ever.”
If effective, the vaccine could be commercially available within a decade, experts told the Daily Express.
The race for a cure comes as figures show Britain in the grip of a dementia epidemic.
It affects 850,000 in the UK, a new case is diagnosed every three minutes and it costs £26 billion a year to treat.
Professor Christian Holscher, a leading Alzheimer’s researcher at Lancaster University, said: “An effective treatment is urgently needed.
“It will be many years until such a novel treatment will come to market. We need more funding to deliver much-needed treatments.”
Dr Laura Phipps, of Alzheimer’s Research UK, said the vaccine had triggered “much anticipation”.
She said: “Clinical trials are the ultimate test but it can take many years to show a potential new approach is safe and effective.”
Alzheimer’s Society research today reveals more than half of dementia sufferers no longer engage in social activities.
They said it benefited them to see more of family and friends and to have help in taking part in activities and hobbies.
Those wanting to volunteer for ongoing and future dementia research should visit: www.joindementiaresearch.nihr.ac.uk