Blood pressure drugs can dramatically cut the risk of Alzheimer’s, scientists reported yesterday.

The drugs both prevent the disease occurring and slow its progression  -  raising hopes of a new weapon in the fight against dementia.

The effect was ‘striking’, cutting the risk of developing Alzheimer’s by more than a third, according to a U.S. study.

Researchers looked at angiotensin receptor blockers, or ARBs, which are normally prescribed as a second choice treatment to patients unable to tolerate ACE inhibitors, another class of blood pressure drug.

What both types of drugs do is interfere with angiotensin  -  a chemical in the body that constricts blood vessels. They allow the vessels to relax and widen so more blood can flow through them.

And that can help cut high blood pressure  -  which in midlife is known to be associated with an increased risk of Alzheimer’s.

Alzheimer’s itself is closely linked to damaged arteries and the appearance of a type of protein deposit in the brain.

Scientists examined the records of about six million patients treated for high blood pressure between 2001 and 2006.

Those taking ARBs were 35 to 40 per cent less likely to develop Alzheimer’s or other forms of dementia than patients on different medications.

Patients already suffering from Alzheimer’s when they started taking ARBs had a 45 per cent reduced chance of developing delirium, being admitted to a nursing home, or dying prematurely during the period of the study.

Those who had experienced strokes before or during the course of their illness appeared to benefit most from the drugs, a Chicago conference on Alzheimer’s was told.