Cognitive enhancers don’t help after 96 weeks in mild cognitive impairment for Alzheimer’s patients

Cognitive enhancers-drugs taken to enhance concentration, memory, alertness, and moods- that are often given to patients with Alzheimer’s disease do not improve cognition or function for those with mild cognitive impairment (MCI) in the long term-about   96 weeks, according to a study published recently in the Canadian Medical Association Journal.

Researchers at St. Michael’s Hospital, Toronto, Ontario, Canada found that cognitive enhancers, including memantine, donepezil, galantamine, and rivastigmine, did not help patients with MCI, which is characterized by memory loss without limitations in day-to-day activity.

“Furthermore, these medications caused significantly more headaches, nausea, vomiting, and diarrhea for patients who took these medications compared to those who received the placebo,” Andrea C. Tricco, MSc, PhD, a scientist in the hospital’s Li Ka Shing Knowledge Institute.

Tricco and colleagues conducted a systematic review and meta-analysis. “A meta-analysis is very powerful, because it allows the analysis of many studies-including many patients-at the same time,” Tricco.

In this case, the study is the amalgamation of 8 randomized clinical trials including 4,711 patients with mild cognitive impairment with ages ranging from 66 to 73 years.

Between 3% and 42% of people are diagnosed with MCI each year, about 4.6 million people worldwide. Each year about 3% to 17% of people with MCI will develop dementia, such as Alzheimer’s disease. Given the aging population, it’s estimated the number of Canadians with dementia will double to more than 1 million in the next 25 years.

“This is only going to increase as the proportion of older people increases. We were interested in determining whether these agents would help patients with MCI and perhaps help slow progression to dementia,” Tricco said.

Cognitive enhancer medications are available to patients with Alzheimer's disease in Canada. “For patients with MCI, special authorization is required,” Tricco said. “Our message is that if patients have obtained these medications through special authorization in Canada, they may wish to have a discussion with their physician to ensure that these medications are indeed working and are not causing them harm.”

This study was funded by the Drug Safety and Effectiveness Network/Canadian Institutes of Health Research.