Novartis, a drug manufacturer, has stopped investigating the CNP520 for Alzheimer's disease. Pharmaceutical companies report this week.
In some test subjects, the drug, also called umibecestat, seems to lead to a decline in cognitive function (recording and processing knowledge).
The researchers then concluded that the potential benefits of the drug outweighed the risk. CNP520 is to delay or even prevent the development of Alzheimer's in high-risk people.
A Novartis spokesman said he was disappointed, but reported that anti-Alzheimer's research and other neurological disorders continued.
Alzheimer's disease is the most common form of dementia. Anyone who has it has more and more memory problems.