Cannabis: The Heart and Brain Risks No One Warned You About

CANNABIS AND HEART HEALTH

In March 2025, findings were presented at the American College of Cardiology’s Annual Scientific Session that linked cannabis use with heart attacks. This presentation combined a study with more than 4.6 million participants and a meta-analysis of 12 previous studies that, in total, involved 75 million-plus people.

The study found that cannabis users under the age of 50 were more than six times likelier to have a heart attack, compared to non-users. And the meta-analysis showed that users had a 50% increased risk of heart attack.

The study also noted cannabis users had a fourfold risk of ischemic stroke, double the risk of heart failure, and a threefold risk of cardiovascular death, heart attack, or stroke. Participants had no “significant cardiovascular comorbidities,” such as high blood pressure or cholesterol, diabetes, tobacco use, or preexisting coronary artery disease.

These findings supported a previous study that was presented at the American College of Cardiology’s Annual Scientific Session in 2023. It found that daily marijuana users were one-third more likely to develop coronary artery disease, compared with those who’d never used the drug.

Similarly, in 2024, the Journal of the American Heart Association reported research that found any use of cannabis (smoking, vaping, or eating) was correlated with an increased risk for stroke and heart attack. Again, this held true even without other underlying cardiovascular risk factors present, including smoking tobacco.

This study analyzed survey data from the Centers for Disease Control and Prevention, tracking 434,104 U.S. adults from 2016 to 2020. It found that “any marijuana use was linked to a higher risk for heart attacks and strokes, but people who used it most frequently had the highest odds.”

Daily users had 25% higher odds of having a heart attack and 42% higher odds of stroke than non-users. Among men under age 55 and women under age 65, marijuana use created 36% higher combined odds for coronary heart disease, heart attack, or stroke.

HOW MARIJUANA AFFECTS YOUR HEART AND BRAIN

It’s no surprise that cardiovascular issues are associated with negative effects on overall cognitive function and mental health. What’s bad for the heart is bad for the brain. Marijuana and brain health don’t mix.

 Amen Clinics founder Dr. Daniel Amen wrote in The End of Mental Illness about his early experience witnessing the connection between cardiovascular disease and depression. After his grandfather, Daniel Ara, had a heart attack at age 69, his personality drastically changed.

Once a happy and positive man, after the heart attack he cried easily, suffered from sleeping troubles, and lost his usual joyful attitude. Eventually, he was diagnosed with major depression and prescribed antidepressant medication.

“He’s one of the main reasons why I fell in love with helping people who are suffering from brain health/mental health issues,” Dr. Amen wrote. “I wish I had known then what I know now about sugar, blood flow, heart disease, and depression.”

Blood flow is critical for the human body—transporting nutrients, including oxygen, to cells while flushing toxins. And the brain especially needs blood flow to function. Though it makes up only 2% of a human’s body weight, it uses 20% of the body’s oxygen and blood flow.

Related: 11 Ways You’re Lowering Blood Flow to Your Brain (and Why You Should Care)

That’s one reason why marijuana, and anything else that inhibits blood flow, will damage the heart and blood vessels—and inevitably harm the brain. Conversely, maintaining heart health helps promote optimal brain health. The link between cardiovascular and mental health has been firmly established in the field of study known as psychocardiology.

Research in this field has shown that those with mental health conditions (including depression, anxiety, bipolar disorder, and schizophrenia) are more likely to develop cardiovascular diseases, even at young ages. And the relationship is bidirectional: People with cardiovascular disease are more likely to suffer from conditions like depression and dementia.

Therefore, protecting the blood vessels that feed the body’s neurons will boost not only heart health, but brain health. The result is a sharper mind as well as improved mental health.

On the other hand, low blood flow has been observed through SPECT brain scans to accompany numerous mental health conditions and symptoms. These include depression, suicide, bipolar disorder, schizophrenia, ADHD, traumatic brain injury, substance abuse, and more. Studies have shown that using marijuana is associated with lower cerebral blood flow.

The effects over time can be devastating. A study of more than 7,700 brain images found that vascular dysregulation within the brain was a key signal in the early development of Alzheimer’s disease. In fact, low blood flow (detectable by SPECT scan) is the #1 predictor that a person will develop this condition.

CANNABIS AND MENTAL HEALTH RISKS

Clearly, the potential mental health effects of cannabis are alarming. Numerous studies have examined the links between marijuana use and brain health, with dangerous implications for mental health.

These effects are particularly insidious for young users (adolescents, teens, and young adults), whose brains are still developing. Studies have found numerous dangers of using cannabis during neurodevelopment, including:

• Disruption of the endocannabinoid system
• Interference with crucial brain processes, including synaptic pruning and neuroplasticity
• Reduced hippocampal neurogenesis, leading to memory deficits and cognitive decline
• Effects on neurotransmitter systems, including the dopaminergic, glutaminergic, and GABAergic systems
• Structural and functional brain changes in the prefrontal cortex and hippocampus
• Decline in cognitive performance, attention, and memory
• Risk for developing dependence, known as marijuana use disorder

In addition, cannabis use boosts the risk for mental health issues. These include psychosis and schizophrenia, as well as mood disorders, such as clinical depression and anxiety disorders. Users may also experience emotional dysregulation.

Related: Scary Ways Cannabis Impacts the Developing Brain

Finally, cannabis inhibits normal functioning, interfering with everyday tasks. The World Health Organization warns that the drug impairs psychomotor skills, affecting coordination and attention.

For example, cannabis can interfere with safe machinery operation for as long as 24 hours after smoking it, raising the risk of dangers like car accidents. Accidents can lead to concussion and traumatic brain injury, which trigger their own negative impacts on the brain and mental health.

Press Play to Discover More About Cannabis and Mental Health

In this eye-opening episode, Dr. Daniel Amen and Tana Amen reveal the darker side of marijuana no one’s talking about. Discover what brain SPECT scans show about its effects on brain health, mental well-being, and mood regulation—and learn why it’s important to know the full story before you decide if it’s right for you.