“The concept of neurons as irreplaceable cells does not hold true today. Experiments and evidence of neurogenesis, also, in the adult brain give hope that some compounds or drugs can enhance this process, helping to reverse the outcomes of diseases or traumas that once were thought to be everlasting.
Cannabinoids, both from natural and artificial origins, already proved to have several beneficial effects (e.g., anti-inflammatory, anti-oxidants and analgesic action), but also capacity to increase neuronal population, by replacing the cells that were lost and/or regenerate a damaged nerve cell.
Neurogenesis is a process which is not highly represented in literature as neuroprotection, though it is as important as prevention of nervous system damage, because it can represent a possible solution when neuronal death is already present, such as in neurodegenerative diseases.
The aim of this review is to resume the experimental evidence of phyto- and synthetic cannabinoids effects on neurogenesis, both in vitro and in vivo, in order to elucidate if they possess also neurogenetic and neurorepairing properties.”
https://pubmed.ncbi.nlm.nih.gov/34684894/
“The current results of cannabinoids effects on neurogenesis are encouraging, and it is expectable that the amount of evidence continues to increase in the future with other experiments.”
“During the last decades, researchers have investigated the functional relevance of adult hippocampal neurogenesis in normal brain function as well as in the pathogenesis of diverse psychiatric conditions.
“Studies have reported changes in the endocannabinoid system in the brain of patients with Alzheimer’s disease (AD), playing a role in the pathophysiology of AD. Cannabinoids have been shown to have neuroprotective properties, reduce neuroinflammation, and enhance neurogenesis. Evidence suggests that the utilization of marijuana products containing both tetrahydrocannabinol (THC) and cannabidiol (CBD) or CBD alone have been effective and safe for use in older people with agitation associated with dementia.
“The endocannabinoid system (eCB) is a ubiquitous lipid signaling system composed of at least two receptors, their endogenous ligands, and the enzymes responsible for their synthesis and degradation. Within the brain, the eCB system is highly expressed in the hippocampus and controls basic biological processes, including neuronal proliferation, migration and differentiation, which are intimately linked with embryonal neurogenesis. Accumulated preclinical evidence has indicated that eCBs play a major role also in regulating adult neurogenesis. Increased 
“The G-protein coupled cannabinoid receptor 2 (CB2) has been implicated in the regulation of adult neurogenesis in the hippocampus. The contribution of CB2 towards basal levels of proliferation and the number of neural progenitors in the subgranular zone (SGZ) of the dentate gyrus, however, remain unclear. We stained hippocampal brain sections of 16- to 17-week-old wildtype and CB2-deficient mice, for neural progenitor and immature neuron markers doublecortin (DCX) and calretinin (CR) and for the proliferation marker Ki67 and quantified the number of positive cells in the SGZ. The quantification revealed that CB2 deficiency neither altered overall cell proliferation nor the size of the DCX+ or DCX and CR double-positive populations in the SGZ compared to control animals. The results indicate that CB2 might not contribute to basal levels of adult neurogenesis in four-month-old healthy mice. CB2 signaling might be more relevant in conditions where adult neurogenesis is dynamically regulated, such as neuroinflammation.”
“The administration of cannabidiol has shown promising evidence in the treatment of some neuropsychiatric disorders, including cocaine addiction. However, little information is available as to the mechanisms by which cannabidiol reduces drug use and compulsive seeking.
