The Forgotten History of Amphetamine Psychosis

In 2024, a highly publicized study in the American Journal of Psychiatry (Moran et al. 2024) showed that people taking drugs like Adderall for attention-deficit/hyperactivity disorder (ADHD) were more than five times more likely to experience psychosis.

At high clinical doses (around 30 mg of dextroamphetamine, or 40 mg Adderall), amphetamine-based drugs were associated with hallucinations and persecutory delusions. The study estimates that 81 percent of such cases could have been avoided at lower doses.

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The study didn’t just find a risk at very high doses. Even those taking moderate doses have a higher likelihood of developing psychosis compared to people not taking them.

The media treated the study as a shocking, even scandalous, discovery. Psychiatrists were quick to assure the public that such side effects are rare. But the link between amphetamines and psychosis isn’t new. It is one of the oldest findings in modern psychiatry.

In 1967, a doctor even used amphetamines to deliberately induce psychosis in ordinary volunteers.

So how do we keep forgetting this lesson? And how can knowing its history help us shape the future?

Discovering Amphetamine Psychosis

Amphetamine psychosis was first named by the British doctor P. H. Connell in 1953. A patient came to London’s Maudsley Hospital experiencing hallucinations, delusions, and paranoia. He was hearing voices and convinced that his boss wanted to murder him over a patent dispute.

Connell admitted him to the hospital with a diagnosis of schizophrenia. A few days later, the symptoms were gone. A careful follow‑up revealed that his psychosis had been induced by large quantities of amphetamines. (At the time, one could purchase amphetamines over the counter as a decongestant.)

Connell wondered if any other doctors had reported this strange side effect of amphetamines. He began to ask his colleagues and dig through case files. He thought he might find three or four cases in the medical literature.

He found 42.

He was appalled that the link between amphetamines and psychosis was not more widely known. He wrote a book called Amphetamine Psychosis to document his findings. He argued in the British Medical Journal for sharper restrictions on their sale.

But Connell’s demands were largely ignored. The problem was that amphetamines were considered a wonder drug on par with penicillin. By the 1940s, amphetamines were prescribed for fatigue, narcolepsy, ADHD, weight loss, and depression. Amphetamines, doctors claimed, could even restore a certain “zest” to life for bored housewives and jaded businessmen.

Nobody wanted to think of them as a pill that could make you mad.

The Quest to Create Insanity

Amphetamine psychosis was rediscovered in the late 1960s due to an epidemic of injectable amphetamine use in the United States.

In the early 1960s, doctors in Southern California wanted to help heroin users get clean by prescribing methamphetamine vials. They thought that injecting amphetamine would be safer and less addictive.

That misjudgment created a large subculture of intravenous amphetamine users—the so-called “Speed Freaks.” They would often develop hallucinations and paranoid delusions. Speed users were regularly showing up at mental hospitals, often misdiagnosed with paranoid schizophrenia.

One doctor became so fascinated by the link between amphetamines and psychosis that he tried to induce psychosis in normal volunteers. He believed that a pill that could reliably create a schizophrenia-like state would benefit mental health research.

He gathered a group of four volunteers—recreational speed users—and gave them amphetamine tablets until they became psychotic. This experiment demonstrated that amphetamines could induce psychosis in people with no prior history of mental illness. His experiment also gave rise to the dopamine hypothesis of schizophrenia, which transformed psychiatry in the 1970s.

The link between amphetamine use and psychosis was briefly rediscovered in the late 1980s, thanks to a paper in the Journal of Emergency Medicine that documented 127 cases (Derlet et al. 1989). The authors noted that such patients were frequently misdiagnosed because doctors did not realize the psychosis was linked to amphetamine use.

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A Forgotten Lesson

So, why do we keep forgetting this lesson? Why was it such a shock when the 2024 article revealed a connection between amphetamine-based drugs like Adderall and psychosis?

One reason is that although doctors knew amphetamines could cause psychosis, they believed this occurred mainly in people who abused amphetamines by taking large doses—far larger than those prescribed for conditions like ADHD.

As long as people were taking clinically approved doses, as judged by their doctor, they were not expected to experience psychosis.

I suspect that another reason was the exact one that P. H. Connell encountered: Nobody wants to think we’re collectively exposing young people to a psychosis risk. In 2022, about 7 million American children were diagnosed with ADHD; that’s about one in 10 kids. About half of them are on medication.

So what does this mean? Does this mean that nobody should take drugs like Adderall? No, not at all. Adderall can certainly be beneficial for some people at some stages of their lives.

But it does mean that we should stop treating amphetamine‑induced psychosis as a shocking anomaly and start recognizing it as a well‑documented risk—one psychiatry has discovered, forgotten, and rediscovered for 70 years.

This post was adapted from my book, The Madness Pill: One Doctor’s Quest to Understand Schizophrenia (St. Martin’s Press, 2026).