Scalp Changes in Androgenetic Alopecia: What Does Ultrasound Reveal?
- Gwen Adey
- May 6
- 3 min read
Most people think of androgenetic alopecia (male or female pattern hair loss) as a condition affecting the hair follicles alone.
The usual explanation is that genetically susceptible follicles gradually shrink over time, producing finer and weaker hairs until hair growth eventually slows or stops.
But a 2024 study published in Skin Research and Technology suggests something potentially more complex may also be happening beneath the scalp surface itself.
Using high-frequency ultrasound imaging, researchers found measurable structural differences in the scalps of people with androgenetic alopecia compared with healthy volunteers.
Importantly, this study does not prove a new cure for hair loss.
But it does support a growing scientific idea:
that androgenetic alopecia may involve changes within the scalp tissue itself — not just shrinking hair follicles alone.
What did the researchers do?
Researchers used a 22 MHz high-frequency ultrasound scanner to examine the scalps of:
30 people with androgenetic alopecia
30 healthy volunteers without hair loss
The scans focused on the crown (vertex) region of the scalp.
The researchers measured:
overall scalp thickness
thickness of tissue beneath the scalp
follicle width
follicle length
number of visible follicles
blood-flow signals within the scalp tissue
What did the study find?
Compared with healthy volunteers, people with androgenetic alopecia showed:
thinner scalp tissue
thinner subcutaneous tissue beneath the scalp
narrower follicles
shorter follicles
fewer visible follicles
reduced blood-flow signals within the scalp tissue
All of these differences were statistically significant.
Why is this interesting?
For years, androgenetic alopecia has mainly been discussed as a condition of “miniaturising follicles”.
This study suggests the wider scalp environment may also be changing.
Researchers are increasingly interested in whether factors such as:
fibrosis
inflammation
tissue remodelling
blood flow
scalp biomechanics
may also play some role in androgenetic alopecia.
This study does not prove any one theory is correct.
But it does provide imaging evidence that measurable structural scalp differences can be detected beneath the surface.
The scalp is more than just skin
One reason this study is interesting is that the scalp is not simply a thin layer of skin with hairs growing through it.
The scalp is a layered biological structure made up of:
skin
connective tissue
fat
blood vessels
nerves
fibrous tissue layers beneath the scalp
tissue covering the skull bone
Hair follicles exist within this wider scalp environment.
That means androgenetic alopecia may potentially involve more than the follicles alone.
So what does this mean for people with androgenetic alopecia?
This study does not immediately change current treatments for pattern hair loss.
But it may help researchers better understand what is actually happening biologically beneath the surface.
If androgenetic alopecia involves wider scalp changes — not just shrinking follicles — that may partly explain why researchers are increasingly studying:
scalp blood flow
fibrosis
inflammation
tissue structure
regenerative approaches to hair loss
The study also highlights how imaging technologies such as high-frequency ultrasound may help researchers study hair loss in ways that previously required biopsy or surgery.
In other words, scientists are beginning to look beyond the hairs themselves and study the scalp environment surrounding them.
Important limitations
This was a relatively small study involving 60 participants from a single hospital in China.
It was also a cross-sectional study, meaning it cannot prove cause and effect.
The study shows that scalp differences exist in people with androgenetic alopecia — but it cannot prove whether those changes:
cause hair loss
happen because of hair loss
or develop alongside it
Larger studies are still needed.
My take as a clinician
One of the most interesting aspects of this paper is that it supports the idea that androgenetic alopecia may be more biologically complex than simply “hairs shrinking”.
Hair follicles exist within a living scalp environment containing connective tissue, blood vessels, nerves, fat, and deeper structural layers.
This does not mean current theories of androgenetic alopecia are wrong.
But it does suggest the wider scalp environment may deserve more scientific attention than it has traditionally received.
High-frequency scalp ultrasound is also an interesting area of development within hair-loss medicine itself.
I have written separately about why I routinely use ultra high-frequency imaging in selected alopecia assessments and treatment planning at Growth Factor Hair Clinic.
The bottom line
This study suggests that androgenetic alopecia may involve more than shrinking hair follicles alone.
The scalp tissue itself may also undergo measurable structural changes beneath the surface.
That does not change current treatments overnight.
But it may help researchers and clinicians better understand what is really happening biologically in pattern hair loss — and why future hair-loss medicine may become increasingly imaging-informed and personalised.
Study referenced:
Li L et al. High-frequency ultrasonography of the scalp: A comparison between androgenetic alopecia and healthy volunteers. Skin Research and Technology. 2024.
Full study:
Written by Dr Gwen Adey BDS MFDS RCS
First published 06/05/26
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