A new drug hailed as a potential breakthrough in the fight against Alzheimer's is still years away from being available in Northern Ireland, an MP whose husband suffers from the disease has said.

Lady Sylvia Hermon said revelations this week about the drug Rember — which has slowed the disease remarkably in a clinical trial — are "truly encouraging".

But, she said, "the major prize" of preventing the killer disease is still elusive.

Lady Sylvia has spoken movingly of the battle her husband, former RUC Chief Constable Sir John Hermon, has fought against what she describes as "a dreadfully cruel disease" since 2002.

Scientists at the University of Aberdeen announced earlier this week that they have developed a drug to slow down Alzheimer's.

Rember is the first drug to target protein "tangles" that kill brain cells.

A clinical trial involving more than 300 people using varying doses of the drug showed that progress of the disease was 81% slower in some patients.

Currently available drugs — there are three used by the NHS — slow the development of the disease, but not in every patient.

The Scottish team behind Rember, working with a Singapore drug company, is seeking cash for further trials and any approval for use in the NHS is still years away, after assessment by the National Institute of Health and Clinical Excellence (NICE).

"Any new positive development in the treatment of Alzheimer's disease is always welcome for sufferers, their families and other carers," Lady Sylvia said yesterday.

"However, the earliest this new drug could be available is likely to be in four years' time and, even then, its use in the NHS will be conditional upon NICE approval.

"So, while initial trials of this new drug are truly encouraging, especially in the treatment of early stage Alzheimer's, the major prize still remains in preventing this awful disease from developing in the first place."

An estimated 26 million people have Alzheimer's worldwide, and the numbers are growing as people live longer.

About 700,000 suffer from dementia in the UK, with about half diagnosed as having Alzheimer's.

Prof Clive Ballard, the Alzheimer's Society director of research, said the Rember announcement is "a major new development in the fight against dementia".

"It is the first realistic evidence that a new drug can slow cognition decline in people with Alzheimer's, by targeting the protein tangles that cause brain cell death," he said.

"This first modestly sized trial in humans is potentially exciting. It suggests the drug could be over twice as effective as any treatment that is currently available.

"However, we are not there yet. Larger scale trials are now needed to confirm the safety of this drug and establish how far it could benefit the thousands of people living with this devastating disease."