The study aimed to understand whether different stimulant medications used to treat ADHD, specifically methylphenidate (Ritalin) and amphetamine (Adderall), pose different risks for developing new-onset psychosis in adolescents and young adults. ADHD is a common condition treated with stimulant medications, which have been increasing in prescription rates, especially among young people. Understanding the potential side effects of these medications is crucial for ensuring safe treatment options.

The study found that the risk of new-onset psychosis was higher for those using amphetamine compared to those using methylphenidate. This was observed consistently across different national healthcare databases, and the findings were supported by various methods to reduce bias. The results suggest that the biological mechanisms of these medications on neurotransmitters might explain the differences in psychosis risk. However, it is important to note that there are several limitations, including potential unmeasured factors such as substance use disorders, which could have influenced the results. Despite these limitations, the findings provide valuable insights into the safety profiles of these commonly used ADHD medications.

Researchers used data from two commercial insurance claims databases, focusing on patients aged 13 to 25 who had ADHD and started taking either methylphenidate (Ritalin) or amphetamine (Adderall) between 2004 and 2015. The main outcome was a new diagnosis of psychosis within the first 60 days of starting the medication, marked by a prescription for an antipsychotic drug.

To compare the risk of psychosis between the two drugs, they used a method called propensity score matching, ensuring patients on methylphenidate were matched with similar patients on amphetamine. The results from the two databases were then combined to get an overall picture.

The study assessed 337,919 adolescents and young adults prescribed stimulants for ADHD. After matching, 110,923 patients on methylphenidate were compared with 110,923 patients on amphetamine, resulting in 221,846 total patients with 143,286 person-years of follow-up. There were 343 episodes of psychosis recorded, translating to about 2.4 cases per 1,000 person-years.

Specifically, the methylphenidate group had 106 cases (0.10%), while the amphetamine group had 237 cases (0.21%). This indicates that amphetamine users had a 1.65 times higher risk of developing psychosis compared to those using methylphenidate.

For adolescents and young adults with ADHD, new-onset psychosis occurred in roughly 1 in 660 patients taking prescription stimulants. The study found that amphetamine (Adderall) use was linked to a significantly higher risk of psychosis compared to methylphenidate (Ritalin).

These findings highlight the importance of considering the type of stimulant prescribed for ADHD, as amphetamine poses a greater psychosis risk. The study was funded by the National Institute of Mental Health and other organizations.