Researchers say drugs known as cognitive enhancers  do not improve mental function in people with mild  cognitive impairment.

Mild cognitive impairment, is memory lapses that may interfere with everyday tasks but is not the same as normal aging.

However, up to 17 per cent of people with MCI go on to develop a dementia  such as Alzheimer’s.

In Canada, doctors need special authorization  to prescribe the drugs for MCI.

Researchers at St. Michael’s Hospital in Toronto reviewed eight randomized trials that compared four cognitive enhancers against placebo pills.

Their report in today’s Canadian Medical Association Journal  says the drugs don’t benefit MCI patients in the long term  and can cause nausea, diarrhea, vomiting and headaches.