Young people on medication for ADHD may have a higher risk of developing psychosis.
The large-scale study has just been published in the New England Journal of Medicine.
It looked at thousands of teens who just started taking stimulants like Adderall or Vyvanse.
It found that they had a much higher risk of psychosis in the first few months of taking the drugs.
The risk did not match up for people who had been using stimulants for a long time.