New Delhi: Drugs designed to treat Alzheimer's disease by targeting amyloid proteins -- seen in high amounts in patients' brains -- have no clinically meaningful positive effects and increase risks of bleeding and swelling in the brain, a new review of previously published studies has found.
While studies of brain scans have shown that patients of the neurodegenerative disease have clumps of amyloid beta proteins, the role of the proteins in advancing the condition is not clearly known -- drugs have however been developed to remove them, in line with a hypothesis that this would help slow down the condition.
Researchers, including those from the IRCCS Institute of Neurological Sciences of Bologna, Italy, analysed data from 17 clinical trials, involving over 20,300 participants with mild cognitive impairment or mild dementia due to Alzheimer's disease.
Findings published in the Cochrane Database of Systematic Reviews show that the absolute effects of anti-amyloid drugs on cognitive decline and dementia severity were absent or trivial, falling well below established thresholds for the minimum clinically important difference.
"Successful removal of amyloid from the brain does not seem to be associated with clinically meaningful effects in people with mild cognitive impairment or mild dementia due to Alzheimer's disease," the authors wrote.
The researchers found that the drugs do successfully remove amyloid proteins from the brain, but this does not translate into meaningful clinical benefit.
"Amyloid-beta-targeting monoclonal antibodies increase the risk of amyloid-related imaging abnormalities," they said in the study.
Lead author Francesco Nonino, a neurologist and epidemiologist at the IRCCS Institute of Neurological Sciences of Bologna, Italy, said, "Unfortunately, the evidence suggests that these drugs make no meaningful difference to patients."
"There is now a convincing body of evidence converging on the conclusion that there is no clinically meaningful effect. While early trials showed results that were statistically significant, it is important to distinguish between this and clinical relevance. It is common for trials to find statistically significant results that do not translate into a meaningful clinical difference for patients," Nonino said.
The review also found that anti-amyloid drugs likely increase the risk of swelling and bleeding in the brain -- this was observed in brain scans without apparent symptoms for most patients, although long-term effects remain unclear since reporting of symptoms was inconsistent across trials, the researchers said.
They added that future trials targeting the removal of amyloid beta proteins are unlikely to provide clear benefit to patients, recommending that research on Alzheimer's treatment should focus on other mechanisms.
Senior author Edo Richard, professor of neurology at Radboud University Medical Centre in the Netherlands, said, "Existing approved drugs offer some benefit for some patients, but there remains a high unmet need for more effective treatments."
"Sadly, anti-amyloid drugs do not offer this and bring additional risks. Given the absence of correlation between amyloid removal and clinical benefit, we need to explore other pathways to help address this devastating disease," Richard said.
This report was published from a syndicated wire feed. Apart from the headline, the EdexLive Desk has not edited the copy.