Kim Collier’s 7-year-old daughter could not stop crying. Less than 24 hours earlier, the child had started taking Vyvanse, a drug prescribed for the treatment of ADHD. The distraught mother suggested a bike ride to distract the inconsolable child. The two set out for a park near their home outside Alliston, Ont. The girl pedalled and sobbed. Then, Collier recalled, “She screamed at me. She said, ‘I want to die.’”