Ketamine has been found to significantly increase expression of hippocampal BDNF in rats and in blood plasma levels of BDNF in humans, and has the ability to induce growth of new synapses and reverse synaptic deficits associated with chronic stress and enhance neuroplasticity. It has been known to work as a potent and rapidly acting antidepressant in treatment resistant depression, and it is possible that part of this effect may be down to the role it plays in modulating neurogenesis.
Chronic ketamine abuse is associated with bladder damage and potential neurotoxicity, but it is possible it could form the basis of a new range of safer and more effective antidepressants.
Cannabis may have a positive effect on neurogenesis. Studies with a synthetic cannabinoid closely related to THC in rats found an increase in hippocampal neurogenesis, with associated anti anxiety and antidepressant behaviour. When this process was blocked via X-irradiation, neurogenesis was blocked and the anti anxiety behaviour was no longer observed, suggesting a link between the two.
Much cannabis has been bred to be high THC (responsible for the psychoactive effects) and low cannabidiol (CBD), which competes for the same receptors in the brain. CBD is more common in indica strains and has been implicated with neurogenesis and as a neuroprotective agent, and research implies it may be neuroprotective against both heavy THC and alcohol exposure. It is a molecule of increasing medical interest; as well as being a powerful antioxidant; it is an anti psychotic compound that balances out the effects of THC. Other cannabinoids have been found to have neurotrophic properties. Cannabichromene has been found to enhance survival rates of neural stem progenitor cells as they differentiate into different types of neuron.
The dipeptide compound Noopept (N-phenylacetyl-L-prolylglycine ethyl ester) has been found to have nootropic and neuroprotective properties in animal studies, and chronic treatment has been found to cause an increase in BDNF expression in rat hippocampus, with an increase in expression of mRNA for BDNF and nerve growth factor (NGF) following acute administration. Agents such as noopept may prove of value in the treatment of some forms of brain damage and associated learning and memory deficits. However long term treatment with noopept may lead to a downregulation of TrkB receptors, which are associated with neurotrophins and of neuronal survival and differentiation in the brain. Thus Noopept may be best used in a cyclical fashion, allowing the brain time to reach equilibrium between uses. Of interest is the fact that the compound may provide little benefit to already healthy brains.
Melatonin is an endogenous neurohormone produced by the pineal gland that has neuroprotective and antioxidant properties and may maintain and augment neurogenesis. It has been found to increase cell proliferation and survival in the hippocampus of ageing mice. The hormone has also been found to enhance the survival of new neurons, and encourage growth and maturation of dendrites and lead to greater dendritic complexity and an increased volume of the granular cell layer in the hippocampus of adult mice. The modulating effect of melatonin in neurogenesis could have important implications regarding cognitive ageing and neuropsychiatric disease. THC in cannabis has been found to profoundly raise levels of melatonin, potentially building on the benefits of THC, CBD and other cannabinoids.
Although melatonin levels decline with age, there are ways to increase production of the hormone, via life style activities such as certain types of meditation and yoga, and one can supplement their own melatonin production through diet, with certain foods such as fruits, seeds, grains and vegetables being rich sources of dietary melatonin and its precursory amino acid, 5-Hydroxytryptophan (5-HTP). Dietary melatonin (cherries, walnuts and ginger are all rich sources) appears to be far superior to taking it in the form of a synthetic supplement.
The act of learning itself is associated with neurogenesis and enhanced neuroplasticity, so a hunger for knowledge and openness to experiencing new things are themselves brain nourishing activities, so a life of learning and experiencing new things is a recipe for a healthy brain. Neurogenesis is a cutting edge frontier of research, and there is still much that remains unknown about the implications of this process and the functional role it plays. We have the power to influence this amazing process however, and it may act to keep depression, anxiety and neurodegenerative diseases at bay, while allowing us to maintain healthy brain function into old age.
One thing is certain, and that is growing yourself new brain cells isn’t going to cause you any harm.
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