Can old drugs provide new hope in the fight against Alzheimer’s disease?

While most drugs developed to treat the disease have proven unsuccessful, research suggests some existing, tried-and-true medications used to treat high blood pressure may offer some protection for the brain against the ravages of dementia.

The drugs, called centrally acting ACE inhibitors and ARBs, are widely prescribed to lower blood pressure, but the medications are also able to penetrate into the brain.

Researchers around the world are finding that the patients who take these drugs are less likely to develop Alzheimer’s and dementia. One U.S study found a 65-per-cent lower risk of dementia among cardiac patients on these medications.

And researchers have just published a study on more than 400 Canadian senior citizens already diagnosed with mild to moderate dementia: Testing over 12 months showed that subjects who were taking these blood-pressure medications showed a slower rate of decline in daily-living activities. The patients were better able to care for themselves or take walks on their own, longer than those not on these drugs.

Lead study author Dr. William Molloy told CTV News that studying the potential of these drugs to treat dementia is critically important, given that so many Alzheimer’s treatments have failed.

“Because we have nothing; we have absolutely nothing,” Molloy said.

Molloy noted that “millions of Canadians” take the medications, and because they have been on the market for years, they are proven to be safe.

“There are no surprises with them,” Molloy said. “Very few side-effects, and they are generic and very cheap. So they have a lot of potential for us.”

With more than 100 failed experimental drug treatments for Alzheimer’s in recent years, researchers, like Sunnybrook Health Sciences neurologist Sandra Black, say there may be new hope in old drugs.

“What we are looking at here ... is called repurposing drugs: taking drugs we already know and that may have other effects than were intended,” Black told CTV News.

She speculates these ACE inhibitors or ARB medications do more than control blood pressure. They may work inside the brain to lower inflammation, or perhaps are stimulating neurotransmitters important for memory and attention.

With so much international interest in these drugs, Black has been given the green light for a new -- and likely world-first -- study, comparing two hypertensive medications: Perindopril (an ACE Inhibitor) and an ARB called Telmisartan. Both are generic drugs.

Black will test their effects on 250 Canadian patients with early Alzheimer’s over one year, measuring brain shrinkage, a common sign of degeneration. Patients will also be tested for changes in memory and quality of life.

If either or both medications appear to put the brakes on the brain disease, they could be readily prescribed to patients since they are already on the market.

“It’s going to be a study that has real implications for front-line care,” Black predicts.

The study, which is expected to take two years, is being funded by the Alzheimer’s Drug Discovery Foundation and the W. Garfield Weston Foundation.

With a report from CTV’s medical specialist Avis Favaro and producer Elizabeth St. Philip