Study Finds Donepezil Best Alzheimer’s Drug for Improving Cognition

Currently, several medications are on the market purporting to enhance concentration, memory, alertness, and moods among those with moderate to severe Alzheimer’s disease. A new study ranking the safety and effectiveness of the four most common drugs found that donepezil (brand name Aricept) was most likely to effectively improve cognition in patients with Alzheimer’s dementia.

However, patients who took donepezil were more likely to experience side effects including nausea, vomiting and diarrhea than those who received a placebo.

The study appears online in the Journal of the American Geriatrics Society.

Canadian researchers report that in 2015, 46 million people worldwide had Alzheimer’s disease. In 2013, 146,593 people aged 65 and older in Ontario alone used cognitive enhancers, according to a 2016 Ontario Drug Policy Research report.

“Alzheimer’s dementia is the most common form of dementia in North America, and most people who have moderate to severe Alzheimer’s will be on these medications,” said Dr. Andrea Tricco, a scientist at St. Michael’s Hospital in Toronto and lead author of the study.

“This analysis will give both patients and clinicians a full picture of how each of these drugs will likely affect their cognition, as well as their overall health.”

Researchers believe the study is the first to rank the comparative safety and effectiveness of Alzheimer’s medications.

Investigators performed a network meta-analysis, an advanced statistical analysis technique, to systematically review existing evidence from 142 clinical trials of four common cognitive enhancers. The trials occurred between 1996 and 2015 with the number of patients in each study ranging from 13 to 2,045. Altogether, the reviewers evaluated a total of 33,889 patients.

The researchers compared the safety and effectiveness of any combination of donepezil, rivastigmine, galantamine, or memantine in treating moderate to severe Alzheimer’s dementia.

Each medication was assessed by the results of the clinical trials that examined cognition, functional behavior, global status, mortality, serious adverse events, falls, bradycardia, headache, diarrhea, vomiting, and nausea.

Donepezil was likely the most effective medication for Alzheimer’s dementia across all effectiveness outcomes, including cognition, behavior, and overall health, according to the study.

Donepezil was also the only cognitive enhancer that reached the minimal clinically important threshold; meaning that effects on outcomes were observed clinically, as well as statistically.

The outcomes were based on the Alzheimer’s Disease Assessment cognition scale, making it the likely first choice for those patients and clinicians considering these medications, the authors said.

Although no significant risk of serious harm, falls or reduced heart rate was associated with any of the medications in the study, the data was limited on these specific outcomes.

Previous research by the authors found that cognitive enhancers do not improve cognition or function in people with mild cognitive impairment, and these patients experience significantly more nausea, diarrhea, vomiting, and headaches.

The findings of the current study will help guide patients and clinicians who are making decisions about the best course of treatment for Alzheimer’s dementia, said Tricco.

“The more information we are able to gather about how each of these medications can affect a patient’s cognition and health, the more likely we are to be able to improve their health outcomes,” she said.

Source: St. Michael’s Hospital/EurekAlert

Photo: Dr. Andrea Tricco. Credit: Courtesy of St. Michael’s Hospital.

Posted by Patricia Adams