Nerve Growth Factor Explained

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It is widely believed in the scientific community that Nerve Growth Factor (NGF) plays a key role in mood regulation, cognitive function, energy levels, and inflammation, among other things. In short, it may be one of the most important elements to achieving well-rounded wellbeing.

But what exactly is it?

Nerve Growth Factor: A Brief Biography

NGF was discovered in 1996 by Italian American neurologist Dr Rita Levi-Montalcini, who subsequently won a Nobel Prize for her work in the field (shared with biochemist Stanley Cohen).

However, despite her career triumphs, Dr Levi-Montalcini was a controversial figure. She made plenty of unfounded claims regarding NGF and its ability to increase her wellbeing and lifespan throughout her admittedly long lifetime (she lived to be a centenarian, dying in 2012 at the ripe old age of 103).

Among her claims, she said that she used NGF eyedrops to contribute to this longevity, a claim of which its scientific validity is completely unfounded. Though many take her long life as evidence of NGF’s efficacy, the reasons behind her extreme age are unknown and unlikely to be linked (at least wholly) to NGF usage.

In fact, many of NGF’s properties have yet to be tested on humans. There is plenty of animal data underpinning it, but scarce usable clinical evidence.

What Is NGF?

It is prevailing scientific wisdom that the brain spends its lifespan constantly reorganizing itself, creating new brain cells, or neurons, throughout. This happens through a process known as neurogenesis – the creation of new neurons.

This neurogenesis relies in large part on a group of small neurotrophins, molecules similar to protein, which aid the development of new neurons and the ongoing health and maintenance of existing ones.

NGF is a key neurotrophin.

Animal research has led researchers to suggest that NGF may therefore help to promote the healthy maintenance of older neurons, the ongoing survival of neurons and axons, and, of course, the growth of new neurons through neurogenesis.

According to this body of research, there is a direct link between decreased NGF production in the brain and a decreased ability for the animal to create new connections and to retain and access memories. Thus, the current working hypothesis is that NGF may mitigate nerve degeneration, or even help to restore their healthy functioning.

This is all based on data from animal studies, so cannot be fully relied on. Human data are needed before we can speak with any kind of certainty.

NGF Levels & What They Mean

It’s hard as yet to gauge exactly what NGF levels in people really mean. As above, the vast majority of research and theory pertains to animals. Without a good body of hard clinical data from healthy adults, everything is at least half conjecture – we cannot know for sure how NGF levels relate to any given person’s health or any disease or set of symptoms.

This being said, there is some tentative data on which we can draw. We can paint a bit of a picture.

For instance, a study from the mid-nineties looked at 157 healthy adults. It found that average NGF levels were around 194 pg/ml. Age didn’t seem to make a difference in NGF levels, but sex did: women had significantly less NGF (at an average of 112 pg/ml) than men did (at an average of 243 pg/ml).

Another study from the same period found that those suffering from a number of autoimmune diseases had high NGF levels. This came hand in hand with heightened numbers of mast cells. These mast cells produce histamine and NGF.

A more recent study found that adults suffering with a common collection of what we might call Western diseases had lower NGF levels than healthy adults. These diseases include atherosclerosis, obesity, type II diabetes, and metabolic syndrome. Researchers have also more recently found a possible link between elevated NGF and BDNF (brain-derived neurotrophic factor, another key neurotrophin) levels and schizophrenia. 

Thus, the relationship between NGF and health isn’t a simple case of the more the merrier – as we can see, higher levels may not be all that healthy.

NGF levels can be a little inconsistent. They can change depending on where you’re taking the test from, which can further confound the data. For instance, you can measure NGF levels in cerebrospinal fluid (CDF), in the blood, and in certain regions of the brain. There is yet to be any kind of correlation drawn between any of these measures.

Researchers have also yet to determine whether or not NGF in the bloodstream can enter the brain.

So, as we can see, this is a very young area of study – a lot more investigation and data are needed before we can fully understand NGF.

What does Dr Levi-Montalcini have to say about it?

So, what can we draw from research into NGF? Well, though it’s tentative, and perhaps a little controversial, let’s return to the source to see what all the fuss is about. Let’s look at what Rita Levi-Montalcini said about it in one of her most famous research papers (The Nerve-Growth Factor: A New Tool for Manipulating Neurons, from 2013).

NGF plays a central role in nervous system formation, per Dr Levi-Montalcini. It can also be used as something of an ‘Ariadne’s thread’ in order to explore nerve-cell growth and differentiation mechanisms.

(An Ariadne’s thread is named for the legend of Ariadne. It is process of solving a problem by multiple means through an exhaustive application of logic to all available routes.)

NGF doesn’t increase the number of neurons per se (in the sympathetic ganglia, per Dr Levi-Montalcini.) Rather, it leads to a marked increase in neuron numbers due to an improved survival rate in redundant immature neurons.

These would usually die off. This kind of cell death is common in the nervous system’s maintenance and development. In fact, it’s been found that dead cells in the sensory and sympathetic ganglia are often far more numerous than live ones in a chick embryo’s early development stages.

Keeping otherwise redundant neurons alive is therefore a big deal.

Scientific consensus in this regard is that immature neurons unable to establish functional connections are there to be killed off. Thus they are redundancies – having too many neurons for the number of connections needed means that there will always be enough to service those connections. All else is waste.

However, according to Dr Levi-Montalcini’s theory, experimentally administered NGF can have some very beneficial results here. It enables those redundant immature neurons to survive. It enables them to differentiate regardless of their inability to establish connections.

Thus, there are far more neurons in NGF-treated sympathetic ganglia. If increased neuron numbers can indeed bring health benefits – which we are unsure of, but seems at least possible, if not outright likely – then the hypothesis is that NGF can bring about said benefits.

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This article was written by: James Dixon – SOMA Analytics PT, Nutritionalist & Published Author

James Dixon is one of the key players in the SOMA Analytics’ team. He is a personal trainer and is educated to Masters level. He is a published author and is a keen advocate of high quality nootropic supplements. James enjoys helping others to reach their peak both physically and mentally and believes that expressing his knowledge through his writing is an effective way to positively impact the wellbeing of others on a larger scale.