Cognitive enhancement drugs only have short-term benefits and can cause significant side-effects for people with mild memory problems, according to researchers.
In a new review of existing data, researchers at St. Michael’s Hospital in Toronto, Canada studied eight randomized clinical trials and three companion reports on the efficacy of four drugs in people with mild cognitive impairment. The drugs were donepezil (Aricept), rivastigmine (Exelon), galantamine (Razadyne), and memantine (Namenda). They found that while the drugs do have short-term benefits, they are lost after a year and a half of treatment.
“As far as what’s out there in randomized clinical trials, these drugs don’t help people with mild cognitive impairment,” Andrea C. Tricco, a researcher with St. Michael’s Li Ka Shing Knowledge Institute, told Healthline.“We found for people who have been given this diagnosis, cognitive enhancers don’t work.”
More importantly, researchers found that those who used these drugs for mild cognitive impairment had a greater risk of headaches, nausea, diarrhea, and vomiting.
Dr. Dean Hartley, director of science initiatives for the Alzheimer's Association, said the study is a confirmation of earlier work, except that this time the researchers focused on earlier stages of cognitive decline.
“This study is important. This is why we need more research,” he said. “Research is the answer to changing the trajectory of the disease.”
Alzheimer’s Drugs and Mild Cognitive Impairment
Aricept, Exelon, Razadyne, and Namenda are approved in the U.S. and Canada to treat Alzheimer’s-related dementia, but researchers examined existing data on their effectiveness for those with mild cognitive decline not related to Alzheimer’s.
While the drugs are only approved to treat Alzheimer’s, in Canada the drugs can be accessed by people with mild cognitive impairment when they have special written authorization.
Mild cognitive impairment is the mental state between age-related mental decline and dementia. Memory problems are typically noticeable by the person and their loved ones, but are not severe enough to interfere with day-to-day living.
About 4.6 million people worldwide have mild cognitive impairment, and between three and 17 percent of them progress to dementia. There are currently no drugs approved by the U.S. Food and Drug Administration (FDA) to treat the condition.
Researchers fear an “indication creep,” where medications for one condition are prescribed to people with similar symptoms. In this case, doctors may be using Alzheimer’s drugs to treat mild cognitive impairment.
Some in the mental health field have hypothesized that cognitive enhancement drugs may delay the onset of dementia, but researchers say there isn’t enough evidence to back up that claim.
“Cognitive enhancers did not improve cognition or function among patients with mild cognitive impairment and were associated with a greater risk of gastrointestinal harms. Our findings do not support the use of cognitive enhancers for mild cognitive impairment,” the researchers concluded in the Canadian Medical Association Journal.
What Can Help Prevent Cognitive Decline?
While the new St. Michael’s study shows that people with mild cognitive impairment aren’t helped by drugs, experts say certain lifestyle choices may be able to slow cognitive decline.
A study from earlier this year in the Journal of Aging Research found that physical exercise is a promising non-pharmaceutical way to prevent age-related cognitive decline and neurodegenerative diseases.
Hartley, as well as others, says that challenging brain exercises, such as crossword puzzles and Sudoku, are good ways to stay mentally and emotionally engaged to prevent decline.
Eating a low-cholesterol, low-calorie diet is another excellent step toward reducing your risk of dementia and other brain woes.
“No data suggest [that] we can change the progression of the disease,” Hartley said. “Those all seem to be things that can slow the progression, but we need more data to ensure that.”