The damage done to the brain by physical trauma doesn’t end with the initial impact. It triggers a series of harmful molecular and cellular events that lead to a damaging secondary injury. But scientists are learning that the brain’s cannabinoid system is a powerful tool for handling TBIs, which means cannabis could become a promising treatment strategy for treating the debilitating condition. The two primary endocannabinoid receptors in the brain, Type I and Type II (CB1 and CB2), both play roles in reducing the extent of injury after head trauma. Normally, there are far more CB1 receptors than CB2 receptors in the brain. However, after injury the number of CB2 receptors jumps. A recent report revealed that activating these CB2 receptors reduces brain inflammation largely by both preventing the activity of pro-inflammatory cells (i.e., M1 macrophages) and enhancing the activity of anti-inflammatory cells (i.e., M2 macrophages). CB2 receptors’ protective effects are largely reached via reducing brain inflammation. CB1 receptor activation also protects the brain from further injury by reducing the amount of excitatory neurotransmitter release, thus preventing the cascade of events that lead to cell death. Activating the CB1 receptor also blocks the expression of pro-inflammatory genes and reduces reactive-oxygen species. Further, activating CB2 receptors reduces the amount of braincell death following injury. So it’s not surprising that activating these CB2 receptors improves many behavioral outcomes after TBI, such as balance, coordination and managing anxiety.
Supplementing endogenous cannabinoid signaling with exogenous cannabinoids, such as those found in cannabis, could help protect the brain from injury by activating CB1 and CB2 receptions. One study looking at the protective benefits of CBD and THC found that CBD had a stronger protective effect without inducing the tolerance associated with THC use. Further, they found that CBD was a potent antioxidant, which reduced the amount of damaging reactive oxygen species. CBD has been shown to reduce inflammation and damage to braincells that provide nourishment, support, and maintain homeostasis in the brain. CBD can also promote neuron growth and development (a process called neurogenesis) in the hippocampus, an important brain region for learning and memory. The hippocampus is one of the first regions to show impairment in Alzheimer’s disease and is often impaired in dementia, thus indicating an additional mechanism in which CBD may provide beneficial effects.