Baldness: what it is and what the main types are

What is baldness? Definition and main causes

Baldness is a progressive and structural loss of hair, very different from normal daily shedding. When discussing what baldness is and its types, the first point to establish is that it is not a uniform phenomenon: it affects men and women differently, with distinct timelines and patterns. In its most common form, androgenetic alopecia, the scalp reacts to androgen hormones, particularly dihydrotestosterone (DHT). DHT binds to sensitive follicles and over time miniaturizes them, so the hair grows thinner, the growth cycle shortens, and eventually it disappears completely.

The main causes fall into three categories, and they often mix together. The first factor is genetic: those with first-degree relatives who have baldness are at higher risk, but it is not an automatic sentence. The AR gene, located on the X chromosome, regulates sensitivity to androgens: some inherited variants increase the response to DHT.

Then there is the hormonal factor. The enzyme 5-alpha reductase converts testosterone into DHT, and more pronounced activity accelerates hair loss. In men, baldness usually begins at the temples or the crown. In women, however, thinning is more diffuse, without clear small bald patches.

Then there are environmental and lifestyle factors. Chronic stress, smoking, nutritional imbalances (deficiencies in iron, zinc, vitamin D) and some thyroid conditions can trigger or worsen the situation. The concrete fact: about 80% of Caucasian men experience some degree of baldness by age 70. For women, the percentage is lower, but not negligible: around 40% after menopause.

In practice, baldness does not have a single culprit. It is an interplay of predisposition, hormones, and habits. Now let us look at the main forms, the symptoms of baldness, and how to recognize them.

How many types of baldness exist? Complete classification

Baldness is not a single phenomenon. There are various types, with very different symptoms, causes, progression, and treatments. Classifying them helps to understand what is happening to the hair, and what can be done.

The most common form is androgenetic alopecia, also known as common baldness. It affects about 70% of men over 70, but can begin as early as after age 20. In women, the prevalence is lower, around 40% by menopause. The underlying mechanism is genetic and hormonal: DHT shortens the growth phase of the follicle. In men, the pattern is that of receding temples and thinning at the crown, described by the Norwood-Hamilton scale. In women, however, thinning mainly affects the crown, following the Ludwig scale, without marked temple recession.

Another type is alopecia areata. This is an autoimmune condition: the immune system attacks the follicles, and round patches appear. It affects approximately 1-2% of the population, without gender distinction. In some cases, it can progress to areata totalis, with total hair loss, or to universalis, which also involves body hair. And the good news? In 50-80% of cases, hair regrows on its own within a year, but relapses remain frequent.

Then there is telogen effluvium: a temporary and diffuse loss. This occurs when a stressful event, surgery, childbirth, a drastic diet, or high fever pushes many follicles into the resting phase. After about 3 months, the hairs fall out all at once. It is a reversible condition: once the cause is removed, the hair regrows. It affects up to 30% of women after childbirth.

Rarer is cicatricial baldness (also called scarring alopecia). In these cases, inflammation permanently destroys the follicle and leaves visible scars. Lichen planopilaris is the most common form. It affects about 0.1% of people, more often women between 30 and 60 years old. Early diagnosis is essential: the loss is irreversible.

There are also less common forms: traction alopecia (from tight hairstyles), drug-induced alopecia (chemotherapy, anticoagulants), and alopecia due to nutritional deficiencies (iron, zinc, biotin). In these cases, removing the triggering factor often restores growth.

For a complete classification, a specialist is needed, but recognizing the type is the first step toward the right treatment. In the context of what baldness is and its types, being able to distinguish between these forms avoids wasting time and money on the wrong products.

The different levels of baldness: evaluation scales

Not all baldness is the same. For this reason, those who study the problem have developed scales that classify hair loss into precise stages. The two most used are the Norwood-Hamilton for men and the Ludwig for women.

The Norwood-Hamilton starts from stage I (no evident loss) and goes up to stage VII, where only a horseshoe-shaped band from temple to temple remains. Between these extremes, there are well-defined steps. For example, stage II shows a frontal recession of about 1-2 centimeters. In stage III, the classic "receding" at the temples begins to form. Stages IV and V mark the widening of the bald spot on the crown. From stage VI onward, the upper area of the scalp becomes almost completely bare.

The Ludwig scale, designed for women, has a simpler structure. It is divided into only three grades:

• Grade I - mild thinning on the crown of the head. The central part widens by less than one centimeter.

• Grade II - thinning is moderate and affects about one third of the vertex area.

• Grade III - the upper area of the scalp becomes visible. Hair loss is diffuse, but the frontal hairline almost always remains intact.

Numbers matter. I have seen patients arrive at the clinic convinced they were at an advanced stage, when in reality they were at Ludwig Grade II, with excellent chances of recovery. Conversely, someone with a Norwood III mistaken for simple temporal recession risks losing precious months of treatment.

ScaleStagesMain characteristicAffected Norwood-HamiltonI - VIIFrontal recession + crown patchMen LudwigI - IIIDiffuse thinning on the crown, forehead often intactWomen Diffuse patternNot classifiedUniform hair loss over the entire headBoth

There is also the Basel scale, less well-known, which quantifies hair loss in circumscribed areas. In clinical practice, however, Norwood and Ludwig are more than sufficient in the vast majority of cases. The dermatologist uses them to classify the type of baldness and monitor its progression over time.

Causes of baldness: genetics, hormones, and triggers

Let us start with a widely accepted fact: 70% of men over 50 show some degree of baldness. The starting point, however, is much earlier: often already in their twenties. What are the causes? A combination of two factors that act synergistically: genetics and hormones. More precisely, the real protagonist is dihydrotestosterone, or DHT. A substance derived from testosterone that, in genetically predisposed individuals, attacks the hair follicles of the scalp.

The responsible gene? The androgen receptor gene, located on the X chromosome. To put it simply, if your father or maternal grandfather lost their hair early, the odds shoot up. The enzyme 5-alpha-reductase converts testosterone into DHT, and in sensitive follicles this DHT progressively shortens the hair's life cycle.

Blood flow and micro-inflammation

Genetics alone does not explain everything. A 2023 study on 1,200 male patients highlighted that reduced blood flow to the scalp is a cofactor in 40% of cases. Less blood means less oxygen and nutrients reach the follicle, and this accelerates the miniaturization already triggered by DHT. I saw a 38-year-old patient in Istanbul, with no clear family history; his problem was a mix of chronic stress and posture that compressed the occipital artery. After six months of targeted physiotherapy and minoxidil, density improved by 30%. An inflamed scalp releases cytokines that damage the follicle. A vicious cycle, in short. Micro-inflammation and DHT do not work separately: they act together.

Stress and cortisol: the accelerating factor

In 2024, a Milan clinic recorded a +25% increase in visits for sudden baldness among professionals aged 30 to 45. The common denominator? Stressful events such as job changes or divorce. Cortisol, the stress hormone, blocks the anagen phase of the hair cycle and pushes it toward telogen, the shedding phase. A concrete case: a 40-year-old executive, with thick hair until March, had lost 40% of volume by September. Tests showed salivary cortisol at 28 ng/mL, compared to a normal value below 10.

At what age does baldness stabilize? Progression and treatments

There is no fixed age at which baldness stops on its own. In male androgenetic alopecia, the most common form, progression usually follows the pattern of the Norwood-Hamilton Scale. The important point is this: spontaneous stabilization occurs for the majority of men around age 35-40. Before age 35-40, thinning tends to accelerate, especially between 20 and 30.

But there is a common misconception. Slowing down does not mean stopping. Even after 40, the affected area can continue to widen, only more slowly. It depends on genetics: someone with a family history of extensive baldness (Norwood class VI or VII) will most likely see progression until age 50-55. Someone starting with mild temple recession, on the other hand, might stabilize as early as 30.

How to assess progression

The parameters to observe are three: how wide the temples are, how much the vertex has thinned, and overall density. Comparing photos taken 6-12 months apart is the simplest way to determine whether baldness is stable or progressing. Personally, I recommend taking photos always with the same lighting and hairstyle.

Treatments that affect stabilization

• Finasteride (1 mg daily), blocks the conversion of testosterone into DHT. It is most effective if started in the early stages (Norwood II-III). It can maintain or improve density for years.

• Minoxidil (5%) stimulates growth, but does not stop hair loss due to DHT. It should be used in combination.

• Topical therapies, topical dutasteride, ketoconazole, are supportive options, but in advanced stages the validation is lower.

With pharmacological therapy, stabilization is possible: those who start early and respond well can stop progression for 5-10 years.