Marihuana: Effects on Neuronal Excitability and Seizure Threshold
- Elisabeth Gordon
- Orrin Devinsky
In the late 19th century, British neurologists found that cannabis had a limited role in epilepsy therapy. Cannabinoid receptors are found in the brainstem, limbic and neocortical areas that modulate seizure activity. The recent studies of the effects of THC, CBD, and related cannabinoids in animal models of epilepsy reveal that (1) the effects vary significantly in different models, in different species, and for the different derivatives; (2) the mechanisms by which the cannabinoids exert their anti-or proconvulsant effects is not well-defined; and (3) the effects of acute administration (e.g., increasing seizure threshold) may be followed, in certain models, by a rebound effect (e.g., decreasing seizure threshold).
No well-controlled studies have evaluated cannabinoids in the treatment of epilepsy patients. However, clinical anecdotes and single case reports suggest that marijuana may reduce seizure frequency or, conversely may provoke seizure activity in select cases, while in most instances it has no significant effect on seizure activity. Several clinical studies have examined the efficacy of CBD on seizure frequency. These studies found either some reduction in seizure frequency or no statistically significant reduction compared to placebo. The few epidemiological studies that have been conducted suggest that marijuana use may protect against seizures induced by illicit drugs such as heroin and cocaine. The limited evidence therefore suggest that marijuana and the cannabinoids may have antiepileptic effects in man, but these effects may be specific to partial or tonic-clonic seizures.
Unable to display preview. Download preview PDF.
In the late 19th century, British neurologists found that cannabis had a limited role in epilepsy therapy. Cannabinoid receptors are found in the brainstem, limbic and neocortical areas that modulate…