Cognitive enhancers—drugs taken to enhance concentration, memory, alertness and moods—do not improve cognition or function in people with mild cognitive impairment in the long term, according to a new study by researchers at St. Michael's Hospital that was published in CMAJ (Canadian Medical Association Journal). In fact, patients on these medications experienced significantly more nausea, diarrhea, vomiting and headaches, according to the study published in the Canadian Medical Association Journal.

It has been hypothesized that cognitive enhancers may delay the onset of dementia, and families and patients are increasingly requesting these drugs. However, efficacy of these drugs for patients with mild cognitive impairment has not been established.

Canadian researchers conducted a review of evidence to understand the efficacy and safety of cognitive enhancers. They looked at 8 randomized trials that compared 1 of 4 cognitive enhancers (donepezil, rivastigmine, galantamine or memantine) to placebo among patients with mild cognitive impairment.

Although they found short-term benefits to using these drugs on one cognition scale, there were no long-term effects after about a year and a half. No other benefits were seen on the second cognition scale or on function, behavior and mortality. As well, patients on these medications experienced substantially more nausea, diarrhea, vomiting and headaches.

"Patients and their families should consider this information when requesting these medications," writes Dr. Sharon Straus, St. Michael's Hospital, Toronto, Ontario, with coauthors. "Similarly, health care decision-makers may not wish to approve the use of these medications for mild cognitive impairment, because these drugs might not be effective and are likely associated with harm."

"Our results do not support the use of cognitive enhancers for patients with mild cognitive impairment. These agents were not associated with any benefit and led to an increase in harms," the authors conclude.