Cannabis has a complex relationship with seizures, which are sudden, uncontrolled disturbances in brain activity. This interaction is not straightforward, involving various compounds within the plant and individual biological responses. Understanding how cannabis affects brain function is central to deciphering its potential to either increase seizure risk or offer therapeutic benefits.
How Cannabis Interacts with the Brain
Cannabis contains over 100 cannabinoids, primarily Tetrahydrocannabinol (THC) and Cannabidiol (CBD). These compounds interact with the body’s endocannabinoid system, a network of receptors and enzymes that regulates various bodily functions, including mood, memory, and stress. The primary receptors in this system are CB1, found mostly in the brain and nervous system, and CB2, located predominantly in the immune system and peripheral organs.
THC is the psychoactive component of cannabis, producing the “high” sensation. It directly binds to and activates CB1 receptors in the brain, leading to effects like euphoria, altered perception, and appetite stimulation. In contrast, CBD does not directly bind to CB1 or CB2 receptors. Instead, CBD influences the endocannabinoid system indirectly and interacts with other receptor systems, such as serotonin receptors. This explains why CBD does not cause intoxication.
Instances Where Cannabis May Increase Seizure Risk
While cannabis has therapeutic uses, certain circumstances can increase seizure risk. High concentrations of THC, especially in large doses, can lower the seizure threshold, making the brain more susceptible to electrical disturbances. Some studies suggest recreational cannabis users, particularly those using high-potency THC products, may have a higher incidence of seizures.
Synthetic cannabinoids (“Spice” or “K2”) pose a significantly higher risk for inducing seizures compared to natural cannabis. These compounds mimic THC but are more potent and unpredictable in their effects on brain receptors, leading to severe neurotoxic outcomes. Emergency room visits for synthetic cannabinoid toxicity frequently report seizures and even coma.
Seizures can also occur during withdrawal from chronic, heavy cannabis use. The body and brain become accustomed to THC, and its sudden absence can disrupt the endocannabinoid system. This can lead to withdrawal symptoms, including physical discomfort and, in some cases, seizures or tremors. This risk is particularly relevant for individuals with underlying neurological vulnerabilities.
Cannabis as a Seizure Treatment
Despite potential seizure risk, certain cannabis compounds, primarily CBD, have anti-convulsant properties. CBD’s mechanisms differ from THC’s; it does not produce psychoactive effects and reduces neuronal excitability through various pathways. Research indicates that CBD can modulate calcium levels within neurons and affect adenosine-mediated signaling, contributing to its seizure-reducing effects.
Epidiolex, a purified CBD oral solution, is approved for treating specific severe forms of epilepsy. This medication is approved for patients aged two and older with Lennox-Gastaut Syndrome and Dravet Syndrome, two rare and challenging-to-treat epileptic conditions. Clinical trials have demonstrated that Epidiolex can significantly reduce seizure frequency in these patient populations. One phase III trial showed a reduction in drop seizures by over 40% in some patients.
Individual Factors and Considerations
The impact of cannabis on seizure activity varies significantly among individuals due to several influencing factors. Individuals with a pre-existing history of epilepsy or other neurological disorders may have a heightened susceptibility to cannabis-induced seizures. This pre-existing vulnerability can alter how their brain responds to cannabinoids.
Genetic predisposition also plays a role in an individual’s response to cannabis, influencing both their susceptibility to adverse effects and their potential to benefit from it as a treatment. While research on specific genetic links to cannabis-induced seizures is ongoing, genetic factors are known to affect how individuals metabolize cannabinoids and the sensitivity of their endocannabinoid system. Dosage and frequency of cannabis use are also determinants; higher doses or more frequent use of THC-rich products may increase risk, while controlled, lower doses of CBD-rich products are used therapeutically.
Poly-drug use with cannabis can further complicate its effects and increase risks. Mixing cannabis with other drugs can lead to unpredictable interactions, potentially exacerbating neurological effects and increasing the likelihood of seizures. These interacting factors underscore the importance of individualized assessment when considering cannabis use, particularly for those with neurological conditions.