Cannabis is famed for causing uncontrollable laughter or “fits of the giggles” in users. Many intoxicating substances can elicit mood changes in users, such as alcohol and various hallucinogens and opiates. The “positive” changes in mood often include feelings of profound joy, pleasure and exhilaration—and an increased propensity for laughter. Historically, many of the dozens of papers that note the phenomenon have simply mentioned its existence without exploring the mechanisms at work too closely. However, now that our approach to understanding psychological processes has matured somewhat, researchers are beginning to pay closer attention to the processes at work when humans use psychoactive drugs, and assessing their potential to improve mood—particularly in depressed or otherwise psychologically-unbalanced individuals.
Cannabis is famed for causing uncontrollable laughter or “fits of the giggles” in users—in fact, even the notorious 1936 film Reefer Madness stated that the first sign of cannabis intoxication was “sudden, violent, uncontrollable laughter”. Dozens of research papers have noted this effect, but the reasons for it remain unclear.
Why the study of laughter is important
Many intoxicating substances can elicit mood changes in users, such as alcohol and various hallucinogens and opiates. The “positive” changes in mood often include feelings of profound joy, pleasure and exhilaration—and an increased propensity for laughter. Historically, many of the dozens of papers that note the phenomenon have simply mentioned its existence without exploring the mechanisms at work too closely.
However, now that our approach to understanding psychological processes has matured somewhat, researchers are beginning to pay closer attention to the processes at work when humans use psychoactive drugs, and assessing their potential to improve mood—particularly in depressed or otherwise psychologically-unbalanced individuals.
A more complete understanding of how human consciousness works will ultimately allow us to treat mood disorders at the source, rather than imperfectly treating the signs and symptoms that arise from the underlying cause of the disorder. One example of this new approach is the recent publicity surrounding depression and its possible basis in immune system inflammation. Initial studies are finding that treating the underlying cause—the inflammation—causes the symptoms of depression to reduce or even disappear. Laughter may also be useful in treating individuals with physical illness or injury, as is has been shown to reduce subjective feelings of stress and pain.
How does laughter naturally occur in humans?
The study of laughter in humans is known as gelotology, from the Greek word gelos, meaning laughter. It is widely understood that laughter occurs in response to internal or external stimuli, such as tickling, jokes, or humorous thoughts. Laughter is a fundamental aspect of human social interaction (as well as that of our closer primate cousins), and can act as positive or negative feedback in social situations. For example, a group of people laughing at a joke made by one of its members acts as positive feedback, while laughing in ridicule at a social error made by a group member acts as negative feedback.
The area of the brain that controls the laughter response in humans is believed to be the ventromedial prefrontal cortex, which lies at the base of the prefrontal cortex and is known for producing endorphins—the “endogenous morphines” produced by the brain, which evoke feelings of euphoria and inhibit pain. It has been variously demonstrated that laughter triggers endorphin release, which in turn increases subjective well-being as well as resistance to pain.
Parts of the limbic system, namely the amygdala, thalamus, hypothalamus and hippocampus, are also believed to be involved in the laughter response. The parts of the limbic system (also known as the reptilian brain) that are involved with laughter are believed to control the raw emotional response to a humorous stimulus, while the ventromedial prefrontal cortex mediates the higher-consciousness aspects of the laughter response, such as suppression of laughter if the social setting is inappropriate. The hypothalamus particularly is implicated in the expression of loud, uncontrollable laughter, such as that often seen in cannabis users.
How does cannabis affect this natural process?
Cannabis has been observed to increase expression of laughter and feelings of elation, euphoria and well-being. Conversely, expressions of anger and hostility are found to be reduced—with the possible exception of sarcasm, which has been found to increase after cannabis use!
The mechanism via which cannabis induces laughter in the user is not fully understood. Cannabinoid receptors are found in high densities in the prefrontal cortex, and are also present (though in varying densities) throughout the limbic system.
Interestingly, a 1993 study into gelastic epilepsy (a type characterised by uncontrolled laughter) found that two individuals suffering from temporal lobe epilepsy with complex partial seizures experienced laughter and a feeling of mirth when the fusiform gyrus (part of the basal temporal lobe) and the parahippocampal gyrus (the region of the limbic system that surrounds the hippocampus, also part of the temporal lobe) were subjected to electrical stimulation. The temporal lobe is also known to provide input to the ventromedial cortex and hypothalamus, and its basal region also contains the hippocampus and amygdala.
Due to the similarity of expression of laughter in these individuals and in cannabis users, the authors of a 1996 review of cannabis and its effect on mood and laughter concluded that a similar mechanism must be at work, and effusive laughter in cannabis users was likely due to stimulation of the basal temporal lobe.
The temporal lobe, epilepsy and cannabis
It seems that the link between cannabis use and temporal lobe epilepsy runs deep.
Individuals suffering from temporal lobe epilepsy often report feeling a sensation of “dreamy languor, during which ego boundaries becomes dissolved, to be replaced by a feeling of cosmic belonging” (see above link), which is remarkably similar to a mind-state commonly reported by cannabis users. Despite the fact that cannabis can apparently create a mind-state very similar to that experienced by temporal lobe epileptics, there is strong evidence that use of cannabinoids can help to manage the severity and frequency of seizures they experience.
Clearly, the complex set of relationships between the various relevant areas of the brain involved in laughter response require further investigation, as our understanding of the processes at work is currently in its infancy. However, as investigation into the properties of cannabinoids and related substances advances, we are rapidly gaining deeper insight into the complexities of human brain function. In time, this will enable the implementation of new, improved cannabis therapies for the treatment of mood disorders.