Scottish scientists have made a major breakthrough in the treatment of Alzheimer's disease which could help millions of sufferers live normal lives.

Already clinical trials of the drug, Rember, have had a dramatic impact on patients, slowing progress of the disorder by 81% over a year and, over the 19-month trial period, they did not experience a significant decline in their mental function.

Sandra Sutherland was one of the 96 people from north-east Scotland among the 321 in the trial to benefit. She had been struggling to cope with her job in accounts for years when she was diagnosed with Alzheimer's.

The 61-year-old, who lives with her husband Ian and two sons in the west end of Aberdeen, was diagnosed with the disease in 2005 during investigations for another medical condition.

"When I was diagnosed I was absolutely gobsmacked," said Mrs Sutherland, now retired. "Now I tell everyone that I meet that I have Alzheimer's and they can't believe it."

Mrs Sutherland, whose hobbies include crosswords and gardening, started taking Rember two years ago. "Since I've been on the trial I feel more confident, more positive, she said. "I think my concentration has levelled off and not got any worse."

Helen Carle, 68, a mother-of-two and grandmother-of-five, was diagnosed with Alzheimer's in 2003 after becoming forgetful and panicky.

She was so anxious she did not like letting her husband, George, out of her sight but, thanks to the new drug, the situation has improved.

"I am still forgetful sometimes but who isn't?" said the former department store assistant. "George has maybe caught the tea before it has burned or has had to turn off the bath taps, but really I think I'm pretty good. I still have the same personality and I think I am more alert."

Rember is the first drug to act on the mass of abnormal fibres of tau protein (tangles) forming inside nerve cells in the brain which was discovered by Alois Alzheimer more than a century ago.

These tangles first destroy nerve cells critical for memory and then destroy neurons in other parts of the brain as the disease progresses.

A team from the University of Aberdeen, working with TauRx Therapeutics, a Singapore-based company associated with the university, revealed the success of their treatment at the Alzheimer's Association International Conference in Chicago.

Professor Claude Wischik, the chairman of TauRx Therapeutics and Professor of Psychiatric Geratology and Old Age Psychiatry at the University of Aberdeen's Institute of Medical Sciences, said: "This is an unprecedented result in the treatment of Alzheimer's disease.

"We have demonstrated for the first time that it may be possible to arrest the progression by targeting the tangles which are highly correlated with the disease."

Consultant psychiatrist Dr Donald Mowat said: "This does seem very encouraging.

He added: "These findings now need to be confirmed in a bigger, international Phase 3 trial and the Aberdeen team are very keen to be part of that."