The digital startup Cerebral began prescribing ADHD drugs like Adderall over the internet, after federal rules loosened. But recently, there have been concerns from inside and outside the company that Cerebral was not careful enough. Now the company has stopped prescribing Adderall to new patients. WSJ's Rolfe Winkler reports. Further Reading: -Startups Make It Easier to Get ADHD Drugs. That Made Some Workers Anxious.  -Cerebral Receives Subpoena From Federal Prosecutors  Learn more about your ad choices. Visit megaphone.fm/adchoices