The American Heart Association (AHA) reported that cannabinoid chemicals in marijuana and hemp may have harmful effects on the brain (Stroke, Feb 10, 2022;53(2)), and presented a review of the scientific literature at the AHA’s 2022 International Stroke Conference in New Orleans. This is an important subject because:
• One-third of 12th graders and half of college students report using marijuana
• Marijuana has been decriminalized in many states to be used as a medicine and for recreation
• The concentration of tetrahydrocannabinol (THC) in marijuana products increased from about four percent in 1995 to 15 percent in 2018.

Marijuana and hemp both contain:
• tetrahydrocanabinol (THC)
• cannabidiol (CBD)
The U.S. Drug Enforcement Agency (DEA) and the Food and Drug Administration (FDA) ) classify THC as a controlled substance, stating that it has a high potential for abuse and little to no medical benefit. CBD is now legal in every state in the U.S., and THC is legal in some states. CBD has been legalized because it is an anti-oxidant and anti-inflammatory chemical that may have health benefits, primarily reducing inflammation and thus helping to relieve pain. Most of the CBD sold today comes from hemp, which contains less than 0.3 percent of THC.

Studies on THC and CBD are Controversial
Animal studies show that the THC in marijuana may cause abnormal behavioral and cognitive damage, particularly if exposure occurs prenatally or during adolescence. However, studies in humans are controversial. The human body produces compounds called cannabinoids, similar to those found in marijuana. Cannabinoids help to regulate learning, memory, pain control and sleep and are necessary for brain development in early childhood. If a child takes marijuana, the THC in it can attach to brain cells and prevent the child’s own cannabinoids from attaching to these brain cells. Animal studies show that prolonged exposure to THC in early life may prevent normal brain development, interfere with memory and learning, and cause abnormal social behavior. Some studies in humans suggest the same results, but others do not. Studies in humans suggest that smoking marijuana can impair memory (Scientific Reports, July 2, 2021;11 (1):13784; Proc Natl Acad Sci, Apr 11, 2000;97(8):4398-403)

Potential Benefits and Harms from THC and CBD
Possible beneficial effects:
• decrease anxiety and depression
• help to prevent seizures
• decrease narcotic and other addictions
• lessen symptoms of multiple sclerosis
• decrease nerve and arthritis pain
• lower high blood pressure

Potential harmful effects:
CBD can cause tiredness, diarrhea, weight gain, and increased risk for side effects of certain prescription medications, dietary supplements or over-the-counter drugs. THC may interfere with learning, memory and brain development in children and may possibly cause strokes, irregular heartbeats or addiction in adults.

Whatever your personal decision on the use of these substances, be aware that there is little reliable research on possible long-term harms or side effects.