About half of American adults have tried cannabis at least once, and usage rose an estimated 65.2 percent between 2015 and 2024, according to the National Center for Drug Abuse Statistics. As usage grows, researchers are increasingly focused on understanding the biological mechanisms of cannabis and its long-term effects on the human body.
The Discovery of the Endocannabinoid System
For centuries, civilizations across Africa, Asia, the Americas, Europe, and the Middle East observed that cannabis appeared to provide relief from nausea, pain, and sleep issues, and influenced appetite. However, the scientific explanation for these observations remained elusive until the late 20th century. In 1964, Israeli researchers Raphael Mechoulam and Yechiel Gaoni identified THC as the primary psychoactive compound in cannabis. This breakthrough led to the discovery of cannabinoid receptors throughout the human brain, immune system, and nervous system. Scientists subsequently learned that the body produces its own cannabinoid-like compounds—such as anandamide—forming an entire biological network now known as the endocannabinoid system. This system helps regulate essential functions including mood, memory, inflammation, sleep, pain perception, and appetite. Because the body possesses these natural receptors, researchers now view cannabis not just as a plant, but as a key interacting with biological locks.
Nuanced Findings in Aging Adults
While much historical research on cannabis focused on adolescents, new studies are examining the effects on older populations. A study from the University of Colorado Anschutz, involving over 26,000 participants from the UK Biobank aged 40 to 77, found that lifetime cannabis use was generally associated with superior cognitive function and larger volumes in specific brain regions. Researchers assessed brain areas with high densities of CB1 receptors, such as the hippocampus, which is critical for memory and typically shrinks with age. The study found that cannabis users often maintained larger brain volumes in these areas and performed better on tests measuring attention, processing speed, learning, and memory. However, the findings are complex. The study noted a dose-dependent relationship where moderate use appeared to offer the most consistent benefits. Additionally, not all brain regions reacted identically; the posterior cingulate, part of the limbic system, showed lower volume in users.
The Challenge of Rigorous Clinical Research
Despite millions of Americans using cannabis for recreational or perceived medical reasons, rigorous scientific research remains limited. According to experts, this is primarily due to strict federal regulations. Because cannabis is classified as a Schedule I substance, researchers face significant hurdles in obtaining authorization to study the drug. At Northwell Health’s Feinstein Institutes for Medical Research, the Human Neuropsychopharmacology Laboratory is preparing to open a facility that will allow researchers to legally dispense cannabis and psychedelics on-site. The lab, directed by clinical psychologist Nehal Vadhan, aims to move beyond survey-based data by observing participants in a controlled environment. The lab features specialized ventilation for smoke, one-way mirrors for observation, and heavy, secure storage for substances.
Scientific Context and Regulatory Hurdles
The intersection of policy and science remains a subject of debate. As research continues, scientists aim to separate what is known from what is merely promising, while acknowledging that science and policy often move at different speeds. Moving forward, the focus remains on understanding the drug’s role in mental health and aging, while accounting for the complexities inherent in human physiology.
