Updated: Dec 11, 2020
Most everyone who has done even a tiny bit of research about hair loss has probably come to accept that dihydrotestosterone (DHT) is what causes it.
This is the narrative that has been widely accepted for several decades: those who are genetically predisposed to DHT sensitivity will likely experience hair loss, it sounds nice and simple, but how often has this narrative been challenged? Hardly ever.
Recently though, there is a new theory about hair loss that has not only gained traction, but also may have data to back its plausibility. It is about the galea: a sheet of fibrous tissue that extends over the scalp, and how changes in its structure could explain hair loss.
In this article, we are going to talk about everything relating to the galea and hair loss. We will detail exactly what the theory is, look at the available research, and ultimately determine whether-or-not it has any merit.
First things first: what is the galea?
The galea is much more than just some fibrous tissue on the scalp.
As you can see from the image above, the galea (epicranial aponeurosis) connects the muscles in the front and back of the head. Sometimes referred to as the “helmet”, the galeas function is to provide protection and mobility for the scalp.
What you might also notice is that the area the galea covers also happens to be where hair loss generally occurs…
The theory about the galea and hair loss
Now onto the interesting part. It might not be a coincidence that the galea covers the exact area where hair loss occurs.
There are actually two main theories regarding the galea and how it might relate to hair loss.
The first theory is the poor posture stretches the galea and this causes reduced blood flow, which subsequently causes hair loss.
When you have poor posture, the muscles in your head and neck are being stretched, meaning that they are under constant tension. Because they are connected to the galea, this means that the tension affects it as well, stretching it tighter over the scalp.
The layer under the galea contains many blood vessels, the bulk of which supply blood to the hair follicles. When the galea is stretched, in theory, those blood vessels become compressed, leading to decreased blood flow. And yes, researchers have studied this (1). This study revealed that there is a “highly significant correlation that clearly identifies a mechanical factor is AGA development”. So not only does this theory make logical sense, but there is also evidence to support it.
Tehre are several other hair loss-inducing processes that may results from the galea being stretched, all of which you can read about here.
The second galea-related hair loss theory is that people with hair loss have a thicker galea, and in this theory correlation = causation.
This theory also relates to blood flow. Since we didn’t cover it in the previous section, let’s go over why blood flow is so important.
Blood supplies your hair follicles with essential oxygen and nutrients that it uses to grow. When blood flow is low, your hair will be starved of these important compounds, meaning that your hair will no longer be able to complete healthy growth cycles. If prolonged, this can lead to miniaturization and eventually hair loss, and is why low blood flow and hair loss are correlated (2).
Now that we know why blood flow is important, the theory is that a thickened galea causes compression of blood vessels in a similar way poor posture does. Has this been confirmed in any studies?
Not any that studied blood flow specifically. But, one study (3) found that in men who were not balding, all layers of the scalp experience thinning with age, but in men with hair loss the galea is the only layer of the scalp that does not thin. This suggests that later in life (later is relative, everyone is different) the galea is thicker in men with hair loss due to its lack of thinning, which could possibly explain blood vessel compression and hair loss.
This could be explained by the decrease in volume of a layer of fat that seperates the galea and the skin.
As you can see from the image above, the scalp is structured in a way that the layer of subcutaneous fat separates the galea and skin. It is well established that as a person ages this layer of fat shrinks (4). As this layer of fat decreases, the pressure between the galea and the skin becomes greater, which, you guessed it, cuts off blood flow to the hair (again, in theory).
In people without hair loss, the galea thins along with the fat, which relieves the pressure, but in people with hair loss where the galea does not thin, that pressure remains.
Both theories not only make sense, but also have research to support the claims. Unfortunately, the hair loss community as a whole, as well as the scientific community have still not investigated it in depth, and are reluctant to consider that hair loss may be caused by something other than DHT.
So, what can you do?
The best thing you can do is to work on your posture. If you can straighten up, not only will you be relieving some pressure from your galea and hopefully helping your hair loss, but there are many other benefits that come from a good posture as well.