#316 - AMA #63: A guide for hair loss: causes, treatments, transplants, and sex-specific considerations
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Hey everyone, welcome to a sneak peek Ask Me Anything or AMA episode of The Drive Podcast. I'm your host, Peter Attia. At the end of this short episode, I'll explain how you can access the AMA episodes in full along with a ton of other membership benefits we've created. Or you can learn more now by going to peterattiamd.com forward slash subscribe. So without further delay, here's today's sneak peek of the Ask Me Anything episode. ♪

Welcome to Ask Me Anything, episode 63. I'm once again joined by my co-host, Nick Stenson. In today's episode, we cover all things related to hair loss. While hair loss is not a direct threat to lifespan, of course, it certainly can be a relatable topic when speaking about aging, and one could certainly make the case that it factors into healthspan and quality of life. It's also a topic I get asked about a great amount through you, the listeners, and also my patients.

In this conversation, we talk about hair loss primarily as it relates to aging, which is a type of hair loss that is called androgenic alopecia. This is the most common form of hair loss for men, certainly, and it also plays a significant role in hair loss for women. We describe the differences, of course, between men and women because they have a very different pattern of hair loss and obviously somewhat different etiologies.

We talk about when the right time to start treatment is and what the breakdown of various treatments are. We cover everything from the pharmacologic uses of minoxidil, finasteride, dutasteride, spironolactone, ketoconazole shampoo, low-level laser therapy, and PRP injections. We then get into the two schools of hair transplantation, talking about the pros and cons of each.

We wrap up the discussion by trying to provide guidance on how to decide which option is best for someone losing their hair, again, male or female, and recapping the differences between the sexes in regard to this. We offer some guidance on what to look for when choosing a specialist or team for treatment.

Finally, I want to note that this is an episode that is available in audio only as we were not able to record this one in video. So without further delay, I hope you enjoy AMA number 63. Peter, welcome to another AMA. How are you doing? Good. Yeah. Thanks for having me back.

I'm always happy to have you back. So a lot of times on our podcast and AMAs, we're getting into topics around lifespan, healthspan, but today is a little different. In a way, we're talking about a subject that doesn't really relate to either lifespan or healthspan. However, it's one of the most common questions. Not only are we asked about through the podcast and the website, but I know it's a question your patients ask you a lot about as well.

which is the topic of hair loss and what you can do about it. So we decided to pull all these questions together and through this we're going to talk about the various causes of hair loss, options available for people to either slow the rate of hair loss or even what they can do once they experience it. We'll look at various treatments and then at the end summarize those into kind of how people can think about what's best for them.

We'll also talk a little bit about what to look for and how people can find a good specialist if they need to go down that route. Lastly, I will say that through this conversation, we will look at hair loss and how it relates to both men and women. So with all that said, I think we can get started, but we should say, I think this is a topic you've never personally thought about, correct? Because how old were you when you started shaving your head?

I shaved my head when I was 22 or 23 years old, 22 actually, and it was a dare. My then girlfriend's dad got dared into shaving his head at work and I

I was like, that actually looks pretty cool. And he's like, well, you should do it too. And so we went out back and he clipped all my hair off and I never once grew it back. So yes, as we were going through this and the preparing for this, there were a lot of questions that I also had about when an individual is losing their hair, what do they notice? Do they notice the

the actual loss of hair density visually? Is that the first sign or do they notice hairs falling out on their pillow or in their drains? I never experienced anything like that because of what's noted. I would point out one thing though, Nick, is potentially something that some might quibble over, which is we said that this really has nothing to do with lifespan. And I think that's almost assuredly true, but you could make the argument that this has something to do for healthspan. For an individual for whom this creates distress, that

that probably does impair quality of life in some way. And so while not traditionally something we think of as healthspan, like physical, cognitive performance, this maybe fits in the bucket of emotional health. And so I guess that's just one more reason beyond all the reasons stated why I think it's an important topic to discuss.

What would it take from a dare perspective to get you to grow your hair back out in its current form for three or four weeks just to see what it looks like? Well, I feel like I've done that before. Three or four weeks is not that long a growth, so I'm not really sure. All right. Well, getting into it, I think...

Just to set the stage, we should start by talking about how common is it for people to experience hair loss as they age for men and women? Look, I think a lot of people will be surprised to understand that hair loss for women is actually quite common as well. But I think before we dive into this, it's worth explaining some of the differences.

Hair loss has a number of causes or potential causes. So today we're going to focus on mainly what's called androgenic alopecia or AGA. And this is the type of hair loss that is responsible for about 95% of hair loss in men.

And certainly at least half of the cases of hair loss in women. So again, when a guy is losing his hair, it is almost always this androgenic alopecia that we're going to talk about. And if a woman's hair is thinning and we're going to spend time talking about the totally different patterns of hair loss that exist here, this is very often also androgenic alopecia. But in the case of women, there are other cases that must be ruled out because they play a much more frequent role.

So, again, it's difficult in women to get clear numbers on this because there are temporary causes of hair loss in women. So any woman listening to this who's been pregnant will absolutely understand that your hair tends to get thicker during the pregnancy. And then post-pregnancy, your hair tends to thin, and it thins usually more than the gain of thickness that you had during the pregnancy. So

Again, do we include that in hair loss for women? Yes or no? That would sort of determine a little bit where these numbers shake out. But I think for the purpose of this discussion, we want to talk about forms of hair loss that are not related to some of the other more treatable causes. So what might those be? Well, autoimmune conditions, along with significant psychological stress and hormonal changes. Again, we talked about those in pregnancy and menopause.

but also deficiencies in certain vitamins and minerals. And the most notable examples here are iron, vitamin D, and B12, along with certain medications. Again, this is really, really rare, but there are examples of people who have experienced reversible hair loss with statins, antidepressants, and even certain antihypertensives. Again, these are exceedingly rare, but certainly worth ruling out.

We'll come back to some of these later, but just to say from now on, when we're talking about this for most of this episode of the podcast, we're going to be referring to androgenic alopecia. Okay, so let's talk a little bit about now the prevalence of this. So male pattern hair loss affects around 30 to 50% of men by the age of 50, and

And female hair loss or female pattern hair loss is also surprisingly common. This was surprising to me. It affects 20 to 50% of women over the course of their entire lifespan. So not quite as significant. And obviously the patterns look very different. We'll include in the show notes what those patterns look like. But nevertheless, it can vary by geography and ethnicity as well. Now, virtually all cases of male pattern hair loss are manifest by age 40.

But female pattern hair loss doesn't necessarily begin early in life. It can certainly begin by age 40, but it may begin as late as age 60. And there are extreme cases where both can begin as early as late teens and even early 20s. Given that prevalence, what do we know about the potential causes of it? Well, it's really a genetic susceptibility married to a hormonal manifestation.

So basically, a genetically susceptible hair follicle is exposed to hormones, most notably dihydrotestosterone, which leads to a process of miniaturization and gradual thinning of the hair shaft over time due to the follicle shrinkage. And that results in finer and finer and shorter and shorter hairs. So people who have listened to this podcast are probably familiar with that

Hormone I just rattled off called DHT or dihydrotestosterone, but we'll take a minute to refresh on it. Remember, both men and women make testosterone. Men make much more of it, typically on the order of 10 to 12 times more of it.

But both men and women will convert the testosterone they have into a more potent hormone called dihydrotestosterone. And I say more potent because it has a much higher binding affinity for what's called the androgen receptor. So remember, every hormone out there only works when it can bind to a receptor. And the receptor that testosterone binds to is called the androgen receptor or AR.

And it binds with a certain affinity. And that's just a fancy word for saying it binds with a certain strength.

But DHT, which is just a derivative of testosterone, one step removed from it, binds at much, much higher affinity. And it varies. Some estimates would suggest 20 times higher. Okay. So you have this hormone called DHT that has even a greater affinity for the androgen receptor. And DHT, DHT binding to hair follicles will actually lead to

this process of miniaturization. And what we think is going on here is, because this is not one gene, to be clear, this is probably polygenic, but probably the most common cause of androgenic alopecia is differences in the susceptibility or sensitivity of the hair follicle to DHT. In other words, it's

It's far less likely that the differences between people who experience baldness and those who do not is the generation of more DHT. In other words, it's probably not something that results in the increase in 5-alpha reductase conversion to DHT, although there are clearly differences there. So to be clear,

There are absolutely clear differences between what's called 5-alpha and 5-beta reductase activity, people who make more DHT versus those who don't. It's just I haven't personally seen evidence, Nick, that that's what's driving the difference in hair loss. Because at the end of the day, even a person who has low 5-alpha reductase activity, which would be genetically determined,

still makes sufficient DHT that if their follicles are sensitive, they're going to ultimately end up losing it. So that's kind of in a nutshell what's driving the process. So what is an implication of that? Well, if you have a person who is increasing their DHT level and they're susceptible, then they're increasing their likelihood of baldness. So taking supplemental testosterone, for example,

is going to increase DHT levels unless you're taking medications to block the conversion of testosterone to DHT, which we'll discuss. And that would accelerate the process in someone who's genetically predisposed. So DHT levels per se are not a marker for androgenic alopecia. And it's not clear if elevated DHT is necessary for

AGA, androgenic alopecia, or whether it's even sufficient. In other words, what I have not been able to find in the literature is a minimum threshold of DHT that if beneath that level is impossible for a hair follicle to come out. So presumably that would be zero, but can hair loss be stopped completely if DHT is below zero?

9 nanograms per deciliter versus 15 nanograms per deciliter versus 5 nanograms per deciliter. I haven't seen those data. I'm just not convinced that that information is known.

So I guess my takeaway on all of this, because I know that that was a much longer answer than you probably wanted, is genetic sensitivity to DHT appears far more important than absolute DHT level. But as we will see, lowering DHT is a very important strategy to either preventing or halting hair loss.

In terms of how hair loss will visibly show up for someone, do we know anything about if there's differences between that visual look for men versus women? Yeah. And I think in the case of men, it's pretty obvious.

Hair loss occurs in the temporal region on the top of the head. And there is a scale that we'll link a figure to in the show notes that kind of walks through the different stages there. I think it's actually female pattern hair loss that's much more nuanced and much more diffuse, and it doesn't resemble that at all. So it tends to begin with a widening right at the part in the middle of the head and the thinning at the top of the scalp.

with potentially a little bit of frontal hairline recession. And of course, women are far less likely than men to experience significant balding, but it's a really different pattern. And again, it all comes down to the sensitivity of the given follicles to DHT. And I'm sure somebody listening will chime in to the following question. I've never seen a great example of, which is what is the evolutionary explanation for this, right? So

Presumably, this is something that

for the most part after the passage of genes. So it's not necessarily a selection feature for mating, but given how conserved it is, I've often wondered if there's something else about it that hasn't been realized. So anyway, if anybody's listening and they've come across some interesting ecology papers on, or at least offering genetic studies

arguments for maybe why the heterogeneity of these polygenic genes have been conserved over so long. I'd be curious to understand that. If someone is sitting there and they're starting to

experience this hair loss that follows these patterns, whether male or female, is it safe for them to assume with how prevalent AGA is that that is the cause as opposed to other causes of hair loss? Or how should they think about that? Yeah. I mean, I think it's always good. And this will be a theme that comes up over and over again. It's best to have these things evaluated by multidisciplinary hair centers, right?

because they tend to bring together the people who can rule out all of the other causes. And while it's true that most of the stress-related problems

medication related hair loss patterns tend to be more diffuse, less patterned, sometimes they're spotty, things of that nature. It is possible that some of these non-genetic causes such as iron deficiency anemia can actually resemble AGA. So I don't think you can just assert that if the pattern doesn't look like

like this, you can assume it's not, or more to the point that if the pattern does look like this, that you don't need to rule out the other things. I think regardless, one should consult with a hair specialist and rule out those other causes.

Last question before we start getting into some of the treatments would be if someone is maybe starting to try and figure out if they are at the early stages of hair loss or let's say they're younger and just trying to understand what their susceptibility to hair loss is as they grow older. Do we know anything about how someone might know if they're at risk for AGA?

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