Androgenetic alopecia (AGA). Not only a male pattern hair loss.
Male pattern hair loss, or androgenetic alopecia (AGA), is the most common hair loss in men, influenced by genetics and hormones. Despite being a natural process, AGA prompts significant spending on hair restoration products. Modern understanding, dating back to Hamilton in 1942, identifies AGA as a genetic predisposition triggered by androgens. In simple terms, normal androgen levels in genetically susceptible individuals lead to hair loss, but not only. The quest for solutions to AGA has a rich historical backdrop, with today's focus on scientific insights and treatments.
Prevalence varies widely, with over 96% incidence reported in Caucasian men. By age 30, over half of Caucasian men are affected, and prevalence increases with age. Positive family history, especially from the father, mother, or maternal grandfather, raises the risk of AGA.
Ethnic differences exist, with Chinese and Japanese men experiencing later onset and lower incidence compared to Caucasians. East Indian and Chinese populations show varying prevalence, while AGA is four times less frequent in men of African origin compared to Caucasians.
In simple terms, AGA involves a natural shift from strong to fine hair, with prevalence influenced by age, family history, and ethnicity.
Diagnosis of androgenetic alopecia (AGA )
Diagnosing and treating conditions like androgenetic alopecia and other scalp diseases and hair loss require the expertise of a professional and experienced trichologist dermatologist. These specialists have the knowledge to consider numerous factors and provide an accurate diagnosis. Factors such as hair loss patterns, variations in hair shaft diameter, and the presence of miniaturized hairs are meticulously examined.
A personalized treatment plan and home routine can then be tailored based on the specific diagnosis. Professionals use specialized tools to assess hair health. For more in-depth analysis, methods like trichogram and trichoscan provide valuable insights into hair density and growth patterns.
Histology: How AGA Alters Scalp Hair and Tissues
In the study of androgenetic alopecia (AGA) through 4-mm punch biopsies, a crucial finding is the miniaturization of terminal hair follicles, transforming them into smaller vellus-like follicles. Interestingly, despite this transformation, the overall number of hair follicles in the affected area remains constant.
When we look at thin sections of the skin, we observe hair with different depths at the bulb and varying diameters of the shaft. As AGA progresses, the growth phase (anagen) of the hair becomes shorter, and there is a higher count of hairs in the resting phase (telogen) in the balding scalp.
The early changes in histology involve specific alterations, starting with focal degeneration around blood vessels in the lower part of the connective tissue sheath of normally growing follicles. This is followed by an immune cell infiltration around the sebaceous duct. In some cases, we may observe multinucleated giant cells. Importantly, there are fibrotic streamers, remnants of the connective tissue sheath, beneath miniaturized follicles. These are always present in miniaturized follicles.
Source: Lidia Rudnicka
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Despite the miniaturization of the hair, sebaceous glands, which produce the skin's natural oils, persist. They may even appear enlarged. This insight into the histology of AGA helps us understand the structural changes occurring at the microscopic level in the affected scalp areas.
Changes in hair cycle in androgenetic alopecia
In men with patterned balding, the gradual change from thick, pigmented scalp hair to fine, colorless vellus-like hair is the key feature of androgenetic alopecia (AGA). Normally, scalp hair follows a cycle with a long growth phase (anagen), a brief transition phase (catagen), and a resting phase (telogen) with an anagen/telogen ratio of 9:1.
However, in AGA, the anagen phase shortens with each cycle, resulting in shorter new hair growth. This makes the hair thinner and finer in each successive cycle. The time between hair shedding and new growth increases, leading to a reduction in the amount of present hair on the scalp. In simple terms, AGA changes the natural hair cycle, making the hair progressively thinner and shorter with each cycle.
The Influence of Androgens on Hair Growth in Androgenetic Alopecia
Androgens, like testosterone and dihydrotestosterone (DHT), play a key role in androgenetic alopecia (AGA), observed as patterned balding in men. Hamilton's studies found baldness didn't occur in castrated men until testosterone was administered. The skin acts as a target for androgens, produced in the adrenal glands and gonads.
Enzymes in the skin, like 5-alpha-reductase, convert testosterone to DHT, the most potent androgen in AGA. In balding scalps, 5-alpha-reductase isotype 1 is more predominant. This process mainly happens in the hair follicles and sebaceous glands, influencing androgen action without relying on elevated systemic levels.
Androgen activation involves binding to a receptor, leading to a cascade of events affecting genes and cellular processes. This can either stimulate or inhibit hair growth. In AGA, testosterone and DHT can induce cell death in hair follicles. Androgen-dependent follicles release insulin-like growth factor-1 (IGF-1), promoting the activity of 5-alpha-reductase.
In simpler terms, androgens affect hair growth, and in AGA, their influence leads to a transformation of thick hair into finer strands. The enzymes in the skin play a crucial role in this process, impacting the hair follicles and sebaceous glands directly.
Unlocking the Genetic Factors Behind Male Pattern Hair Loss
Having a family history of AGA significantly increases the risk. Researchers believe there's a genetic link, but the exact inheritance pattern is not clear. Some suggest autosomal-dominant inheritance, while others lean towards polygenic inheritance. The expression of IGF-1, a protein linked with insulin resistance and hyperinsulinemia, also seems important, with lower levels found in the scalp tissue of balding individuals.
In simpler terms, your genetic makeup, including family history and specific gene variations, can impact the likelihood and extent of male pattern hair loss. Understanding these genetic factors helps us grasp why some individuals are more prone to AGA than others.
Connections Between Male Pattern Baldness and Health Risks: Understanding Beyond Blood Tests.
Early-onset vertex balding, particularly before 35 years of age, may signal an increased risk of early-onset coronary heart disease, especially in young men with hypertension or dyslipidemia. Those with early androgenetic alopecia (AGA) also face a higher incidence of hyperinsulinemia and related disorders like obesity, hypertension, and dyslipidemia.
Interestingly, men with male pattern baldness, particularly at the vertex, have a greater incidence of prostate cancer. The exact reasons are unclear, but researchers are exploring shared androgen pathways linking coronary heart disease, insulin resistance, and prostate cancer.
Importantly, it's not just about the level of dihydrotestosterone (DHT) in the blood. Even if DHT levels are low in blood tests, individuals may still experience hair loss and be at risk for heart and prostate diseases. It's crucial to understand that bald men often have similar testosterone levels as others but exhibit high sensitivity of their receptors to DHT. Therefore, relying solely on blood test results may not provide a complete picture.
It's essential to emphasize that androgenetic alopecia is not a disease itself but a symptom of DHT sensitivity, strongly associated with heart and prostate issues. Regular blood tests, coupled with proper consultations, trichoscopy, and trichogram analyses, are vital for a comprehensive understanding of an individual's health. Taking proactive steps, such as consulting with a specialist trichologist or dermatologist, is crucial for those experiencing symptoms or concerns about their health. Regular health check-ups and awareness are key to overall well-being.
Please note: The information provided here is for informational purposes only and does not constitute medical advice. If you have any serious health issues, are taking medications, or have concerns about your health, please consult your GP or a medical advisor.