High blood pressure increases the risk of Alzheimer's
Researchers believe a drug used to lower blood pressure could be even more effective against Alzheimer's disease than they previously thought.
People taking angiotensin receptor blockers (ARBs) were up to 50% less likely to develop dementia than those taking other blood pressure drugs.
Combined with another drug, ARBs also protected against further deterioration among those already with the disease.
The study of more than 800,000 men appears in the British Medical Journal.
The team from the Boston University School of Medicine presented initial results from the study two years ago, but further work suggests that ARBs - normally prescribed only to patients who cannot tolerate the more standard ACE inhibitors - confer greater protection than had been thought.
The search is on for an effective means to guard against Alzheimer's - and delay deterioration - as the number of people worldwide with the condition is set to soar as life expectancy grows.
Latest calculations suggest more than 115 million people across the globe will suffer from dementia by 2050.
High blood pressure over long periods can lead to damaged blood vessels, and this is known to increase the risk of not only strokes and heart disease, but dementia as well.
Some types of dementia are directly related to the condition of the arteries supplying the brain, but blood pressure is also thought to play a role in Alzheimer's disease, which is linked to the appearance of protein deposits in brain tissue.
Staying at home
Researchers looked at records of more than 800,000 people - 98% of whom were men - treated for high blood pressure between 2002 and 2006.
Those who took angiotensin receptor blockers (ARBs) were up to 50% less likely, over that period, to be diagnosed with dementia compared with those on other blood pressure medication.
When taken in combination with ACE inhibitors, the risk was even further reduced.
Of those with a diagnosis of dementia, this same combination meant they were 67% less likely to be admitted to a nursing home or die prematurely.
The reasons why the drug may have this effect are unclear, but it is thought it may help prevent nerve cell injury from blood vessel damage, or help the nerve cell recover after the vessel has been damaged.
"This new research not only adds to the evidence that treatments for high blood pressure could help stop the development of dementia but suggests that some of these treatments may be more suited to this than others," Dr Susanne Sorensen, head of research at the Alzheimer's Society.
"The prospect of using already existing drugs to help in the fight against dementia is attractive. However, more research is needed to weigh up the benefits of this type of treatment as a protective tool."