As we all know, the scalp and hair have an interdependent relationship due to their proximate structural arrangement. Scalp condition and hair loss have been studied simultaneously when examining the hair matter with esthetic problems, biological problems, and pathologies.
However, while the protective benefits of the hair to the scalp are palpable, the role of the scalp as an incubator environment for the preemergent hair fibers is often overlooked. Thus, understanding more about scalp health and scalp disorders may offer insights into managing hair conditions.
A Closer Look Into The Scalp
The scalp includes terminal hair follicles, an enlarged epidermal surface as a result of numerous hair canals, and countless sebaceous glands. These glands contribute to a specific environment, which provides conditions for microbes to develop. Indeed, there is a microbiome – a community of all microorganisms – existing on your scalp (yes, this includes bacteria and fungi)
A microbiome on the scalp consists primarily of Propionibacteria, Staphylococcus bacteria, and Malassezia yeast. While the first two bacteria are associated with a healthy scalp, Malassezia is often linked to troublesome conditions. Also, this yeast can contribute to oxidative stress, a problem associated with scalp diseases, alopecia, and aging.
That is to say, in addition to physiological conditions, the scalp environment is responsible for skin pathologies as well. Under pathologic conditions, your scalp can suffer from a wide array of conditions , including dandruff and seborrheic dermatitis, psoriasis, atopic dermatitis, and alopecia. Several studies have shown that these conditions often connect with oxidative stress causing the imbalance between reactive oxygen species (free radicals) and antioxidant defenses in our bodies. This issue happens when the production of oxygen-reactive species becomes excessive, causing damages to cells and tissues of the human body.
Scalp Disorders And Diseases
1. Dandruff and Seborrheic Dermatitis
Seborrheic dermatitis is a skin condition that causes an itchy rash with flaky scales. In general, dandruff and seborrheic dermatitis can appear because of fungi from the genus Malassezia. After their emergence, they inflict irregular construction and dis-organization of the epidermis. Besides, both have clear signs of oxidative stress manifested by perturbed surfaces and levels of systemic antioxidant enzymes, and lipid peroxidation elevated.
It is noteworthy that your scalp has not only a specific micro-environment but a higher rate of exfoliation, a process of removing the dead cells from your skin's surface. It means that some degree of flaking can appear even on a normal scalp when you don't wash your hair within 1 or 2 weeks.
However, pathological dandruff is more troublesome than that. This condition results from an over-acceleration of epidermal cells. Then, the structure of their outermost layer is damaged, followed by their increased exfoliation under abnormal keratinization. Frequently, factors causing dandruff are microbial colonization of Malassezia fungi, sebaceous lipids, and individual sensitivity.
Meanwhile, seborrheic dermatitis is a chronic recurrent condition. Its characteristics consist of scaling and red patches and flakes, usually in sebaceous areas. In some cases, those patches can spread beyond the folds of the nose and eyebrow. Studies have shown that one possibility explaining the appearance of seborrheic dermatitis is related to Malassezia. Indeed, its fungal metabolites, especially free fatty acids released from sebaceous triglycerides, constituents of body fat, cause inflammation on the scalp, then seborrheic dermatitis.
This is a chronic inflammatory condition of the scalp. Psoriasis is the most thoroughly studied skin condition linking oxidative stress, the role of Malassezia, and the risk of hair loss. The overgrowth of Malassezia, and oxidative stress, including altered antioxidant enzymes, oxidized proteins, and oxidized lipids, are generously observed on the scalp that suffers from this disease.
The severity of this scalp disorder varies vastly. Some may experience mild symptoms and minor irritation, but the condition could be severe for others. In contrast to seborrheic dermatitis, its manifestations are sharply differentiated red, flaky, crusty patches of skin covered with silver-white scaling.
3. Atopic Dermatitis
This scalp condition is well known as a chronic, relapsing, and inflammatory skin disorder that could alter the scalp significantly. The mechanism in which this disease develops is complex and involves diverse factors, namely genetics, environmental conditions, disrupted skin permeability, and immunologic mechanisms.
Similar to other scalp diseases, atopic dermatitis strongly connects with Malassezia and oxidative stress. Such scalp conditions could be exacerbated through the impacts of the environment.
4. Scalp Aging
Although protected from ultraviolet radiation (UVR) by the hair, the scalp still ages with time, with the manifestation considerably similar to skin aging. However, scalp aging happens differently among individuals because of diverse factors, such as general health, nutritional status, lifestyle, hygiene, or risk factors. One factor playing a vital role in the aging process is oxidative stress which increases with age due to the degeneration of the body’s defense mechanisms. The net result of these effects is the decreasing ability of the skin to heal itself, with an increase of skin pathologies.
Aging is a result of a set of time changes from both programmed and non-programmed factors. The former goes after a biological timetable, depending on changeable expressions of genes. And then, these expressions affect the systems responsible for maintenance, fixation, and protective responses. Meanwhile, the latter includes different levels of internal and environmental attacks, such as UVR.
For non-balding scalps, effects of aging are relatively unnoticed, although, underneath the hair, the scalp is likely to pale and dry with different extents of laxity. On the contrary, it is easier to see the features of premature skin aging on a balding scalp, including irregular pigmentation, wrinkling, atrophy, spider veins, and skin-related premalignant and malignant diseases.
The Interdependent Relationship Of Scalp Condition And Hair Health
Research has explored the relationship between scalp health and aspects of hair quality. The most common manifestation of hair emerging from an unhealthy scalp is an altered cuticle with evidence of surface pitting, roughness, cuticle rigidity, or breakage. In some cases, shine reduction may appear. In addition to the physical changes, there are also biochemical alterations, with both protein and lipid components affected, most commonly by oxidative damage.
Some studies have explored the relationship between scalp health and hair conditions. The emergence of dandruff, seborrheic dermatitis, or psoriasis causes negative influences on the pre-emergent hair fiber, thus altering the anchoring force of hair fiber with the follicle. In trichogram, examiners have found that in scalp with such diseases, the proportion of both catagen and telogen hair increased along with anagen hairs without hair root sheaths.
Table 1 below shows the summary of scalp abnormalities, the most common manifestation of hair emerged from an unhealthy scalp.
While the scalp is the incubator environment for pre-emergent hair, research has found many scalp diseases that could significantly alter hair health. There are several common diseases such as dandruff, seborrheic dermatitis, psoriasis, and atopic dermatitis. The common factor responsible for them is metabolites of Malassezia, one of the mass fungal colonizers on your scalp. Oxidative stress also contributes to the development of these diseases as well as premature hair loss. Moreover, it triggers scalp aging, a sign of a reduction of scalp functions.
How to support your hair to achieve a better look
While cosmetics cannot treat any diseases and it's always best to seek medical advice when you experience any of the above, certain products may be suitable for improving the appearance of your hair.
When creating your routine, make sure to pick a shampoo that can help you cleanse your scalp gently yet effectively. A serum containing specific ingredients may complement your routine for scalp care.
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Schwartz, J. R., Messenger, A. G., Tosti, A., Todd, G., Hordinsky, M., Hay, R. J., Wang, X., Zachariae, C., Kerr, K. M., Henry, J. P., Rust, R. C., & Robinson, M. K. (2013). A comprehensive pathophysiology of dandruff and seborrheic dermatitis - towards a more precise definition of scalp health. Acta Dermato-Venereologica, 93(2), 131–137. https://doi.org/10.2340/00015555-1382
Saxena, R., Mittal, P., Clavaud, C., Dhakan, D. B., Hegde, P., Veeranagaiah, M. M., Saha, S., Souverain, L., Roy, N., Breton, L., Misra, N., & Sharma, V. K. (2018). Comparison of Healthy and Dandruff Scalp Microbiome Reveals the Role of Commensals in Scalp Health. Frontiers in Cellular and Infection Microbiology, 8, 346–346. https://doi.org/10.3389/fcimb.2018.00346