The blood pressure drugs that block the protein angiotensin could reduce the risk of developing Alzheimer's disease and other forms of dementia, according to the online British Medical Journal Wednesday.

In a study, scientists in U.S. found that older people taking a certain type of blood pressure medication known as angiotensin receptor blockers (ARBs) were significantly less likely to develop the brain-wasting illnesses.

"We think it (angiotensin) is one of the most important factors determining healthy blood vessels and also acts in the brain to help neurons to be a little more resilient," said Benjamin Wolozin, the senior author of a report on the findings.

Wolozin, also a professor of pharmacology and neurology Boston University School of Medicine, and his colleagues looked at the incidence of dementia in 800,000 mostly male patients in the U.S. from 2002 to 2006. They all had heart disease and were 65 or older.

The patients were divided into three groups. One of them was using ARBs, another was taking a different type of the blood pressure lowering drug, an angiotensin-converting enzyme (ACE) inhibitor called lisinopril, and a third was on other heart medications.

Among patients, those who took ARBs were nearly half as likely to be needing admission to a nursing home by the end, according to the study.

The team also found that ARBs have an added effect when combined with ACE inhibitors in patients who had already developed Alzheimer's or dementia. Those taking both drugs were less likely to die early or be admitted to nursing homes.

However, the study had its limitations. Colleen Maxwell and David Hogan of the University of Calgary, Canada, said the study did not factor in family history of dementia; was rather short in duration; and did not look at dementia among women.

There are 35 million people worldwide having a form of dementia such as Alzheimer's disease and the tally will almost double every 20 years -- to 66 million in 2030 and more than 115 million in 2050, Alzheimer's Disease International predicted.