A new Irish study has found that a class of drug, which is used to lower blood pressure, can slow down the rate of cognitive decline commonly seen in cases of dementia.

The study found that these drugs may also improve brain power.

The team from University College Cork's Centre for Gerontology and Rehabilitation focused on the class of drug known as ACE inhibitors. These drugs work by making the blood vessels relax, which lowers blood pressure.

The researchers looked at 361 patients who had been diagnosed with vascular dementia, Alzheimer's disease or a mixture of both. Their average age was 77.

Eighty-five of the participants were already taking the blood pressure drug, while the remainder were not.

The team also assessed the brain power of 30 patients who had been newly prescribed ACE inhibitors in the first six months of their treatment for dementia.

The cognitive decline of each patient was assessed twice between 1999 and 2010 using standardised tests.

The researchers found that those taking ACE inhibitors displayed slower rates of cognitive decline compared to those who were not taking the drugs. The difference was small but significant, they said.

Furthermore, they also found that the brain power of the participants who had been newly prescribed the blood pressure drugs improved over the six-month period, compared with those not taking them, and even those already taking them.

The Cork team suggested that this may be because these patients strictly adhered to their drug regimen, or it could be a by-product of improved blood pressure control.

However, the researchers emphasised that this is the first time that ACE inhibitors have been shown to not only reduce cognitive decline, but potentially boost brain power as well.

"This study supports the growing body of evidence for the use of ACE inhibitors and other [blood pressure lowering] agents in the management of dementia. Although the differences were small and of uncertain clinical significance, if sustained over years, the compounding effects may well have significant clinical benefits," they said.

However they warned that recent studies have indicated that ACE inhibitors may be harmful for some people, therefore if these findings are confirmed in further studies, only certain people with dementia may benefit.

Details of these findings are published in the journal, BMJ Open.

For more information on dementia, see our Alzheimer's Clinic here