(NBC News) Certain medications used to treat ADHD in teens and young adults may be more likely to cause symptoms such as paranoia, hallucinations, delusions and hearing voices, a new study suggests.

Researchers found that patients who had been newly prescribed amphetamines, such as Adderall and Vyvanse, were more likely to develop psychosis than those who had received a prescription for methylphenidates, such as Ritalin and Concerta, according to the study published Wednesday by the New England Journal of Medicine.

While psychosis with either class of medication is still relatively rare — occurring at a rate of one in 660 patients — experts cautioned that patients should know about the increased risk.

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