April 18, 2024 - This study found that cannabis use during adolescence was associated with alterations in brain function in medial prefrontal cortical and insular brain regions during cognitive task.

Autoradiographic and positron emission tomographic studies of the rhesus monkey and human brain have shown high densities of CB1 receptors in the cerebral cortex (cingulate gyrus, middle frontal gyrus, entorhinal cortex, and Wernicke’s area), hippocampus, caudate/putamen, globus pallidus, substantia nigra, and cerebellum (17,18). This receptor distribution is consistent with the psychoactive actions of THC and thereby with potential effects of cannabis on memory, stress-responsivity, reward, and motivated behavior, as well as self-monitoring.

November 20, 2025 - Large study examined the effects of cannabis use on 1,000 adults. Researchers found 63% of heavy cannabis users exhibited reduced brain activity on a task.

Neuroimaging has also revealed changes in white matter, the neural fibers critical for efficient communication among brain regions, in early-onset cannabis users. Cannabis products are everywhere these days. As a growing number of states loosen their medical and recreational cannabis laws, millions of Americans are using the cannabis sativa plant, typically known as marijuana, to relax or treat pain, anxiety, insomnia, and other conditions. Gruber is especially excited about her team’s research on medical cannabis and its effect on cognition, brain structure, function, and quality of life.

July 24, 2025 - Recent cannabis use (defined as within 24 hours) in youth and adults has an immediate impact on thinking, attention, memory, coordination, movement, and time perception.1 · Cannabis affects brain development. Developing brains, such as those in babies, children, and teenagers, are especially ...

Cannabinoid receptors are expressed ... of active brain development.6 Acute intoxication with cannabinoids can impair memory and behavioral inhibition.7 Cannabinoids also regulate anxiety and can produce psychosis-like effects.6 ...

January 2, 2025 - This cross-sectional study examines the association of lifetime cannabis use and recent cannabis use with brain function during cognitive tasks among young adults.

The latest findings are shedding light on how biological brain differences may influence cognitive effects in adolescent users, how cannabis can interfere with pharmaceutical medications for depression and other mental health issues, and the potential mental benefits for older adults.

Despite the observed age of onset effects, longitudinal studies are needed to determine causality of these effects. The rate of marijuana use has had a steady increase since 2007 (1). Among >400 chemical compounds, marijuana’s effects are primarily attributed to δ-9-tetrahydrocannabinol (THC), which is the main psychoactive ingredient in the cannabis plant. THC binds to cannabinoid receptors, which are ubiquitous in the brain...

March 17, 2014 - Current knowledge is mostly inferred from animal studies; it has been demonstrated that the main psychoactive component of cannabis (Δ9-Tetrahydrocannabinol, THC) induces dose-dependent toxicity and structural changes in brain regions rich in cannabinoid CB1 receptors. These are mainly located in the hippocampus, amygdala, cerebellum, prefrontal cortex, and striatum (Burns et al, 2007; Downer et al, 2001; Lawston et al, 2000). In contrast to the animal literature, the investigation of the structural effects of long-term cannabis use on the human brain has brought less consistent findings.

This scientific statement is intended ... unknown effects of marijuana on brain health,” said writing group Chair Fernando D. Testai, M.D., Ph.D., FAHA, a professor of neurology and rehabilitation at the University of Illinois at Chicago. This is the Association’s first scientific statement on cannabis and brain ...

October 30, 2024 - Previous studies have found that regular cannabis use is associated with a decline in neurocognitive abilities and has had a damaging effect on brain structure and function.

February 25, 2020 - In addition, a significant correlation has been found between the age at which regular cannabis use commenced and axonal connectivity, particularly in brain regions abundant with cannabinoid receptors in the developing brain (Zalesky et al., 2012). Further support for these findings comes from animal studies, which consistently suggest that cannabis may permanently impair cognition, but that this effect is modified by age of exposure. It has been shown, for example, that cannabis may have detrimental cognitive effects only when consumed during periods of brain development (∼40 days in rats which parallels 16 years in humans) (Schneider and Koch, 2003).

May 28, 2024 - Overall, these results challenge the assumption that CBD can make cannabis safer, as CBD did not attenuate THC effects (and in some cases potentiated them); furthermore, they show that cannabis causes similar disruption to resting-state connectivity in the adolescent and adult brain. ... Adolescence is a period of intense brain maturation characterized by ongoing structural and functional changes [1], particularly in the endocannabinoid system, where there is rapid maturational development of corticolimbic neuronal populations [2]. Some evidence has suggested that chronic cannabis use during t

January 2, 2025 - In this study of young adults, lifetime history of heavy cannabis use was associated with lower brain activation during a working memory task. These findings identify negative outcomes associated with heavy lifetime cannabis use and working ...

The authors found cannabis users performed the task less accurately and failed to deactivate the right hippocampus across conditions. In another study by the same authors, nicotine withdrawal elicited increased activation across brain regions in the marijuana group, including parietal cortex, superior temporal gyrus, posterior cingulate gyrus, and the right hippocampus. The same effect was not found in the tobacco-only control group suggesting marijuana use may lead to developmental changes masked by nicotine use [54, 55]

A longitudinal study of 799 European adolescents published in 2021 linked cannabis use with a thinning of the prefrontal cortex in regions where cannabinoid receptors are expressed, and with higher levels of impulsiveness.

Some studies also found a thinning of areas of the brain involved in cognition and orchestrating thoughts and actions, but other studies found no differences in the brains of marijuana users and non-users.

May 31, 2024 - THC was also associated with connectivity changes that could impair the brain from efficiently adapting or reconfiguring to changing stimuli · BOSTON – A new study led by investigators from Massachusetts General Hospital, a founding member of the Mass General Brigham healthcare system, reveals that the main psychoactive component in cannabis or marijuana disrupts the normal connections and activity of the brain’s prefrontal cortex, a region that is crucial for decision-making and self-control.

December 14, 2021 - Cannabinoids act like a type of “dimmer switch,” slowing down communication between cells. So how does THC affect the EC system? When someone smokes marijuana, THC gets into the brain rapidly and attaches to cannabinoid receptors.