Two events happened within weeks of each other this year. Together they may say more about the marijuana debate than any campaign advert ever could.

In Washington, the Drug Enforcement Administration wrapped up historic hearings on whether to reschedule marijuana under federal law. At the same time, Massachusetts confirmed that voters will face a ballot question this November. They will decide whether to repeal the state’s licensed recreational marijuana sales system. It is the first real attempt to roll back commercial marijuana sales at the ballot box since legalisation began sweeping the country.

Both decisions, according to psychiatrist Dr Daniel Amen, come down to the same underlying question: what does cannabis actually do to the brain?

What the Scans Reveal About Cannabis and Brain Health

Dr Amen founded Amen Clinics and has built one of the largest brain imaging databases in the world. He is a leading voice on cannabis and brain health. Speaking on the High Stakes podcast with Kevin Sabet, president of Smart Approaches to Marijuana, he described what he sees when comparing scans of heavy marijuana users with healthy brains. The pattern, he said, is consistent. Blood flow drops across almost every region. The sharpest fall is in the hippocampus, the part of the brain responsible for memory. It is also the same region first affected in Alzheimer’s disease.

Dr Amen published a study of 1,000 marijuana users. It found reduced blood flow and activity throughout the brain, most notably in the hippocampus. A separate study of another 1,000 users, this time younger participants, appeared in JAMA Psychiatry. It reached a similar conclusion, recording decreased activity in the brain’s learning and memory centres.

This month, a study in The Lancet Psychiatry added further weight to the marijuana and brain health debate. It concluded that there is no universally safe level of marijuana use. Regular use, the researchers found, is a cause of psychosis, not merely something linked to it.

Why Teenage Brains Are Especially Vulnerable

Dr Amen also works as a child psychiatrist. He said the effects often show up first in teenagers who are mistakenly diagnosed with attention difficulties. He described seeing adolescents referred by worried parents who believed their child had ADD. In many cases, no such history existed before marijuana use began. What follows, he said, is often a scan he called bumpy and toxic looking.

He linked early and heavy use to a higher incidence of anxiety, depression, suicide and psychosis among teenagers and young adults. Many turn to marijuana because they have not learned how to manage difficult thoughts, he argued. The underlying issue, though, never actually resolves.

From an NBA Star to Toddlers in the Emergency Room

Among his patients is NBA player Julius Randle, who Dr Amen has treated for almost three years. According to Dr Amen, Randle’s wife said heavy marijuana use changed his personality. He went, in her words, from warm and connected to angry and distant. Dr Amen said trauma work helped address the adverse childhood experiences behind Randle’s struggles. Seeing his own brain scan, he added, was enough to convince Randle to stop. A year later, both the scan and his patient’s wellbeing had improved considerably.

The conversation also turned to children far younger than professional athletes. Dr Amen pointed to a sharp rise in accidental exposure. He cited figures showing a forty fold jump in emergency room visits for children under five linked to marijuana poisoning. Toddler cases, he said, now outnumber combined incidents involving paracetamol, aspirin and other painkillers. Sabet referenced a recent case in Texas. A four year old was hospitalised after a THC infused lollipop ended up in a party goodie bag.

For very young children, Dr Amen said the brain is undergoing rapid development. Disrupting that process, even temporarily, carries a risk that is not yet fully understood. He raised particular concern for children with a genetic predisposition toward psychosis. Early exposure, he warned, could activate long term vulnerabilities.

Ageing Brains and the Path Back to Recovery

Beyond adolescents and children, Dr Amen’s research also points to premature brain ageing. Alongside Dr Cyrus Raji of Washington University in St Louis, he analysed scans from 64,000 people to map how the brain changes over a lifetime. Brain function typically stabilises in the mid twenties and holds steady until around sixty. It then naturally declines. Severe psychiatric illness accelerates that decline significantly. Marijuana use, the analysis found, was the next most notable factor associated with a brain that looks older than a patient’s actual age.

Sleep has emerged as another concern. A recent piece in the Washington Post examined how marijuana disrupts deep sleep, the restorative stage the body relies on most. It is a pattern, Dr Amen said, that matches what he regularly sees among his own patients.

Rather than leading with the risks, Dr Amen said his approach with teenagers starts differently. Through a high school programme called Brain Thrive by 25, students are taught to see their brain as central to how they think, feel and relate to others. Only afterwards does any discussion of drugs or alcohol take place. The course, he said, has been shown to reduce drug, alcohol and tobacco use. It also lowers depression and improves self esteem. Framing the conversation around self interest, rather than authority, tends to resonate far more with teenagers than simply being told something is bad for them.

Both men agreed on one final point. The same brain imaging that offers such a stark warning about cannabis and brain health also offers hope. The brain, Dr Amen said, retains a genuine capacity to recover once marijuana use stops and healthier habits take hold.

Marijuana is now legal in some form across roughly forty states. A federal rescheduling decision is pending, and Massachusetts voters are preparing to weigh in this November. The debate around marijuana and the brain looks set to remain firmly in the spotlight well beyond this year.

Source: youtube