The phenomenon of the munchies resulting from smoking marijuana offers valuable insight into our brain's ability to experience joy and happiness, as well as its role in preventing obesity and depression. The desire for food while under the influence of marijuana is thought to stem from the activation of marijuana receptors in the feeding centers of the brain. Scientists became interested in this topic and conducted clinical trials with a new drug, rimonabant, that blocks the brain's marijuana receptors, with the goal of reducing food consumption and helping overweight patients. Early results were promising, with participants reporting reduced cravings for food and decreased interest in other substances like alcohol, cigarettes, and cocaine. The potential benefits of the drug, especially given the significant risks associated with obesity, generated considerable excitement in the medical community.
After long-term use of rimonabant, patients reported serious side effects including severe depression and suicidal thoughts. It appears that the drug blocked one particular type of marijuana receptor in the brain too effectively, causing patients to lose their ability to experience pleasure. This discovery suggests that our natural marijuana system plays a role in regulating mood and pleasure, and blocking it can have dangerous consequences.
The study of the munchies has led to interesting connections between the brain's marijuana system and anti-depressant drugs.
The reason behind the feelings of sadness and hopelessness associated with depression is still unclear, but there are a number of biochemical changes that take place in the brain during depressive episodes. One of the most significant changes is a decrease in neurogenesis, or the formation of new neurons, in a brain region called the hippocampus. Antidepressants like Prozac and Zoloft have been found to increase the rate of neurogenesis in the hippocampus, which helps to alleviate the symptoms of depression. However, a drug called rimonabant that was effective in reducing food cravings also decreased neurogenesis, leading to depression and suicidal thoughts in some patients. On the other hand, my lab's research has found that a small daily dose of marijuana can actually reverse the age-related decline in neurogenesis, potentially providing a new approach to treating depression.
These studies highlight the importance of our brain's marijuana neurotransmitter system in regulating hunger, happiness, and normal brain processes like neurogenesis. While it's dangerous to constantly block this system with drugs like rimonabant, we don't yet know if it's also dangerous to constantly stimulate it. More research is needed to fully understand the effects of marijuana on the brain and its potential as a treatment for depression.