The New York Times says the trial was immediately stopped but all the men may be brain damaged, and may not recover.
The men took part in the trial at the Centre Hospitalier Universitaire de Rennes, in eastern Brittany.
The patients, all men, were ages 28 to 49.
The drug was administered orally to healthy volunteers as part of a Phase One of a trial which is meant to help sufferers of neurodegenerative diseases.
Of 128 participants, 90 were given the drug, and the rest a placebo.
Ms Touraine said the drug had previously been tested on animals, including chimpanzees. The first symptoms appeared quickly and the trial was immediately stopped.
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