CNS drugs have accounted for around 1 of every 10 FDA drug approvals since the 1980s, reports the Tufts Center for the Study of Drug Development.

Despite the constancy, the researchers also note that the category has a high frustration rate, finding that CNS drugs development times are typically 18% longer than for non-CNS drugs, and that just one of out every six CNS drugs managed to wrangle the FDA’s Priority Review label between 1999 and 2003, while other drugs had a rate of around 50%.