What is Neurogenesis?
Neurogenesis is the growth of new neurons, which was originally believed to be absent in the adult brain [R].
We now know that neurogenesis occurs in two areas of the adult human brain: the hippocampus and the subventricular zone (SVZ) [R]. The function of the SVZ is relatively unknown in humans.
Stem cells and precursor cells (similar to stem cells but more restricted in what they can turn into) are needed for neurogenesis. They are essentially “blank slates” that are able to develop into neurons and other brain cells [R].
Neurogenesis in the Hippocampus
What is the Hippocampus?
The hippocampus is a part of the brain that plays a key role in learning and memory, spatial navigation, and control of emotion [R].
Why Increase Neurogenesis in the Hippocampus?
The hippocampus helps turn short-term memory into long-term memory [R].
In 1953, the link between the hippocampus and long-term memory formation was revealed after an epileptic patient had surgery to remove parts of his hippocampus. The patient developed severe amnesia after the surgery [R].
It has since been confirmed that the hippocampus helps create new memories and ensure their long-term survival [R].
Neurogenesis and Neurological Diseases and Disorders
In animal models of TBI, increasing neurogenesis improved post-injury brain function [R].
Compounds Involved in Neurogenesis
Different compounds play critical roles in adult neurogenesis [R]:
- Morphogens are molecules that regulate the maintenance, survival, and development of precursor cells
- Neurotrophic factors (like BDNF) are molecules that protect neurons and help new neurons grow and mature
- Neurotransmitters like GABA, dopamine, glutamate, and serotonin
- Transcription factors (including TLX and Sox2) are involved in precursor cell division and the development and organization of neurons
Ways to Increase Neurogenesis
1) Exercise Increases the Number of Neurons
Running doubled the number of new cells in the hippocampus of mice [R].
2) Mental Exercise Increases the Survival of Neurons
Learning new skills (particularly challenging ones) increases the survival of new neurons in the hippocampus [R].
3) Sleep Promotes the Growth of New Neurons
Short-term sleep deprivation (less than one day) has little effect on neurogenesis [R].
4) Sex May Stimulate the Growth of New Neurons and Improve Memory
Both acute and chronic sexual activity increases neurogenesis in rats [R].
Sex prevented a decrease in neurogenesis and improved memory in chronically-stressed mice [R].
5) Meditation Reduces Stress
Diet & Nutrition
6) Flavonoids Protect the Brain
Flavonoids are a group of compounds found in most fruits and vegetables.
- Increasing brain blood flow and preventing the death of neurons [R]
- Increasing BDNF [R]
- Reducing depression [R]
- Increasing precursor cells [R]
Ketogenic diets are low-carb and high-fat, and they induce the body to burn fat as its primary fuel source.
A ketogenic diet increases neurogenesis in mice with epilepsy [R].
However, another study reported that a ketogenic diet had no effect on neurogenesis in adult rats [R].
8) The LMN Diet
The LMN diet is a therapeutic diet rich in polyphenols and polyunsaturated fatty acids.
The LMN diet increases neurogenesis in mice by increasing precursor cells and mature neurons [R].
9) Omega-3 Fatty Acids Increase the Connections between Neurons
Herbs, Supplements, and Drugs
10) Resveratrol Improves Learning and Memory
Supplementation with high doses of resveratrol leads to an increase in new neurons [R].
Resveratrol increases angiogenesis (the formation of new blood vessels) and levels of growth factors that are associated with neurogenesis. These changes lead to improved learning and memory [R].
11) Phosphatidylcholine Protects the Neurons
Phosphatidylcholine is a lipid that is a key component of cell membranes.
Long-term curcumin use increased neurogenesis in chronically-stressed mice. It also prevented the decrease in serotonin receptors and BDNF in the hippocampus due to stress [R].
Curcumin also increased the number of new cells in the hippocampus in healthy adult mice [R].
14) Nootropics Improve Cognitive Function
NSI-189 showed antidepressant properties and improved cognitive function in patients with major depressive disorder. It also increased mice hippocampal volume by 20% [R].
15) Pregnenolone May Help with Alzheimer’s
Pregnenolone also preserved hippocampal neurogenesis in a mouse model of Alzheimer’s, with an associated improvement in cognitive function [R].
16) DHEA Increases the Number of New Neurons
Pregnenolone is a precursor of dehydroepiandrosterone (DHEA).
DHEA increased the number of new neurons in the rat hippocampus and prevented decreased hippocampal neurogenesis from corticosterone, a stress hormone [R].
17) Chlorogenic acid Improves Memory
18) Uridine Increases the Synapses between Neurons
Uridine is an important ingredient in mother’s milk that contributes to the generation of new synapses in infants [R].
Uridine-5’-monophosphate (UMP) increased new synapses in an animal study [R].
Apigenin and related compounds increase hippocampal neurogenesis in mice [R].
20) Ashwagandha Prevents the Loss of Neurons
Ashwagandha (Withania somnifera) is an adaptogenic herb (promotes balance in the body).
Withanoside IV (a compound found in Ashwagandha) prevented loss of neurons caused by amyloid beta plaques in the hippocampus and brain cortex. This suggests that ashwagandha may benefit Alzheimer’s patients [R].
21) Ayahuasca May Stimulate the Growth of New Neurons
Ayahuasca contains the psychoactive compound dimethyltryptamine (DMT) and has anti-depressant and anti-anxiety properties [R].
Banisteriopsis caapi (one of the components of Ayahuasca) stimulates the development of neurons from precursor cells in mice [R].
22) Gotu Kola Protects the Neurons
Asiatic acid (a compound in Gotu Kola) increased neurogenesis in the hippocampus of mice [R].
23) Cerebrolysin Protects the Neurons
Cerebrolysin is a mixture of peptides derived from the brain of pigs.
In a mouse model of Alzheimer’s, cerebrolysin restored neurogenesis and decreased cell death in the hippocampus [R].
Similar effects were observed in the subventricular zone (part of the brain) in mice after stroke [R].
24) Ibogaine Increases the Growth of Neurons in the Hippocampus
Ibogaine is a natural psychoactive substance found in plants of the Apocynaceae family.
Lithium generated new cells and prevented their death in the hippocampus of mice [R].
Lithium also prevented the death of progenitor cells and improved learning in mice [R].
Lithium improved cognitive function and stimulated neurogenesis in a mouse model of Alzheimer’s [R].
Psilocybin is a compound with hallucinogenic and euphoric effects that is produced by more than 180 species of mushrooms.
Low doses of psilocybin increased new neurons in the hippocampus in mice [R].
27) Ginseng May Enhance Memory and Cognitive Function
Rg3 is a member of the ginsenoside class of compounds and is found in Panax ginseng.
Cell studies show that Rg3 causes the generation of neurons from stem cells [R].
28) SSRIs (antidepressants)
29) Testosterone and DHT Increase the Survival of New Neurons in the Hippocampus
Testosterone and its derivative dihydrotestosterone (DHT) increased hippocampal neurogenesis by increasing the survival of new neurons in mice [R].
In rats, testosterone prevented the decrease in neurogenesis caused social isolation [R].
30) Red Light Therapy Helps Regenerate Neurons
Red light therapy (through low-level laser therapy) helps protect the brain and nerve cells after a stroke, traumatic brain injury, and other brain disorders. The mitochondria in the cells absorb red light and cause responses in nitric oxide, cyclic AMP, and reactive oxygen species [R].
In various studies, red light therapy increased neuron axonal regrowth, neuron regeneration, and provided overall nerve cell protection after brain injuries [R].