(New York Times) – New research suggests that dosage plays a role in a rare side effect of A.D.H.D. stimulants.

Psychosis and mania are each known side effects of stimulant medications, and the Food and Drug Administration has added warnings to the medications’ labels saying that they may cause symptoms like hallucinations, delusional thinking or mania. But these side effects are considered rare — experienced by an estimated 1 in 1,000 patients — and have not been extensively researched. It can take months for someone to fully recover.

A new study published on Thursday in The American Journal of Psychiatry suggests that dosage may play a role. It found that among people who took high doses of prescription amphetamines such as Vyvanse and Adderall, there was a fivefold increased risk of developing psychosis or mania for the first time compared with those who weren’t taking stimulants. (Read More)