There have been enough negative consequences to the mainstreaming of marijuana that the political popularity of legalization has stalled out. Some places are, or may soon be, regretting and even rethinking its legalization.

In City Journal, Manhattan Institute senior fellow Stephen Eide offers another reason for regret and second thoughts. The greater availability and general pervasiveness of pot have increased the intersection of the drug with mental illness. “Communities that have legalized have seen an increase in cannabis-related hospitalizations,” Eide observes. And even if these represent victims of acute rather than chronic psychosis, the sorts of people who quickly figure out that they smoked a bit too much, many others are not so rational.

Almost half of adults with mental illness are marijuana users. Moreover, “legalization normalizes pot use, creating barriers to treatment for mentally ill users whose symptoms worsen with cannabis.” Why should they stop doing what is now accepted in more social classes and settings than ever before?

It is at least possible — and, Eide argues, necessary — to account for the dangerous intersection of marijuana and mental illness in the provision of mental health care. “No mental-health policy plan should be considered complete without some provision about trying to keep schizophrenics and bipolar people off weed,” he writes. Other than that, unless or until the tide turns on full legalization and social acceptability of marijuana, it will be difficult to do much more for this already troubled population.