Marijuana May Speed Up Brain Aging and Hampers Development in Youth, Warns Psychiatrist

19 July 2025

Psychiatrist and brain‑imaging expert Dr. Daniel Amen warns that marijuana use during adolescence and early adulthood may prematurely age the brain and stunt development that continues until about 25 or 26. Drawing on decades of SPECT scans from his clinics, Amen reports that cannabis users consistently show reduced blood flow in multiple brain regions, particularly those connected to memory and decision‑making, which could underlie long‑term cognitive deficits.

He highlights that teenage users exhibit higher rates of anxiety, depression, suicidal thoughts, and psychosis. Alarmingly, he cautions that recreational use may impair young minds more than cocaine or cigarettes. A French study revealed that marijuana users face a greater risk of heart attack and stroke than users of cocaine, and a Canadian study linked cannabis-related hospital visits to early dementia Amen’s findings also pointed to more severe lung damage among marijuana smokers than cigarette smokers.

One of the most disturbing trends Amen observed was parents consuming cannabis alongside their teenage children, which he described as “going the wrong way” He stressed that using cannabis or alcohol during the formative years disrupts normal neural development, potentially leaving permanent damage even if use ceases.

The human brain depends on a robust supply of blood to fuel oxygen and nutrient delivery. Marijuana’s impact on cerebral blood flow especially in regions like the hippocampus can accelerate brain aging, sometimes by nearly three years, according to long-term imaging studies. The hippocampus is essential for memory formation and learning, making these effects particularly troubling for youth.

Brain development extends well into the mid-twenties, meaning interference at an early age may undermine a person’s mental and emotional potential. Data shows lowered blood flow corresponds with greater incidence of serious mental health disorders, including bipolar disorder, schizophrenia and depression. Cannabis use, particularly when heavy or early, is linked to higher risks of psychosis and schizophrenia, especially in genetically predisposed individuals.

Physician-researchers are increasingly warning that the widespread belief in cannabis as a benign substance, or even a safe medicinal aid, needs reevaluation. While cannabinoids deserve thorough study, recreational use remains under-examined and carries hidden neurological costs.

Dr. Amen advises against recreational cannabis during adolescence and encourages parents to lead by example. He urges policymakers to integrate this knowledge into public health guidelines and educational campaigns focused on youth brain protection.

This evidence signals a critical shift in how we understand cannabis: as a potentially harmful agent to developing brains, capable of prematurely aging neural structures and raising long-term risks for mental health and cognitive decline. As legalization and access expand, experts argue it's essential that messaging evolves too, emphasizing age‑specific vulnerabilities and promoting informed responsibility.