Drugs used to treat high blood pressure could slow the rate of cognitive decline in dementia patients, research suggests.
ACE Inhibitors, which are also sometimes used to treat some cases of diabetes or some forms of kidney disease, may even boost brain power in dementia patients, scientists said.
The researchers examined 361 patients, with an average age of 77, who had been diagnosed with Alzheimer's disease, vascular dementia, or a mix of both.
Eighty-five of the patients were already taking ACE inhibitors; the rest were not.
For the study, published in the online journal BMJ Open, each patient's cognitive decline was assessed using one of two standardised mental state examinations on two separate occasions, six months apart.
Compared with those not taking ACE inhibitors, those on these drugs experienced marginally slower rates of cognitive decline - researchers found a small, but significant, difference in patients who undertook the more sensitivities of the two tests.
And the brain power actually improved for 30 patients newly prescribed these drugs, during their first six months of treatment, they said.
The authors said: "(These) patients started on centrally acting ACE inhibitors while attending clinic, showed a median improvement rather than a decline in scores over the first six months of treatment."
They added: "Cognitive scores may improve in the first six months after centrally acting ACE inhibitor treatment and use of centrally acting ACE inhibitors is associated with a reduced rate of cognitive decline in patients with dementia."
Dr James Pickett, head of research at the Alzheimer's Society, said: "We've known for some time that high blood pressure increases your risk of developing dementia.
"Any drug which halts cognitive decline is potentially exciting - as it has the ability to radically improve people with dementia's quality of life.
"The more we learn about dementia and how it relates to other conditions like high blood pressure, the more we're able to explore whether existing drugs such as these can double as dementia treatments.
"However, people should not start taking any drugs that they have not been prescribed and should instead speak to their GP. One in three people over 65 will develop dementia. We need much more research into potential treatments to enable people to live well with the condition."