Synonyms in a broader sense
dandruff, pityriasis simplex capillitii, head borrhoea, pityriasis simplex capitis
The skin consists of three layers from the outside to the inside. The epidermis is a cornified squamous epithelium that produces and supports an impermeable horny layer, which is the outer boundary layer of the epidermis. Underneath this layer are the dermis and the fatty tissue (subcutis).
Other components of the skin are the skin appendages:
- Hair
- Nails
- Sebaceous glands and sweat glands
The keratinocytes (skin cells of the epidermis) represent a continuously renewing cell population in which cell gain (proliferation) and cell loss (desquamation) are in balance. The outer boundary layer of the epidermis is the end product of the development of the keratinocytes. However, the resulting horny layer is not a fixed structure, but is constantly renewed by outward exfoliation and proliferation of keratinocytes from below.
The average renewal time of the entire epidermis is one month. After that, the dead cells are shed and are sometimes visible as scales. Different stimuli can cause excessive tissue proliferation (hyperproliferation) and the formation of visible scales.
The dead skin cells (corneocytes) are now proliferated and rejected faster than in people who do not have a dandruff problem. In addition, the scalp produces its own “lubricant”, sebum, with the help of the sebaceous glands. It keeps skin and hair soft and supple.
If too much sebum is produced, the rejected horny cells can clump together and become detached in visible accumulations of dandruff (aggregates). One of the causes that can trigger the increased and too fast rejection of dead skin cells is improper hair care. Through too frequent hair washing or too hot blow-drying, the sebaceous glands are no longer able to produce sufficient fat and dry, flaky skin develops.
But also different diseases can be the cause of dandruff. A very common problem is seborrheic dermatitis, or seborrheic head eczema, in which an overproduction of sebum (seborrhea) and the increased multiplication of certain microorganisms, such as the yeast fungus Malassezia furfur, play an important role. This fungus is normally an inconspicuous part of our skin flora and breaks down sebum and dead cells.
However, if the balance of the scalp is shifted, e.g. due to improper care, the fungus can multiply and thus trigger itchy centres of inflammation. The scalp reacts to this inflammation with increased dandruff formation, which in turn promotes the growth of the fungus. The seborrhoeic scalp eczema is caused by the increased sebum production and the associated clumping of prematurely dead horny cells, which are massively exfoliated.
In 1-2% of the population this disease pattern occurs and should be treated with an antimycotic. Other disease-related causes associated with dandruff are neurodermatitis, psoriasis or other fungal diseases of the skin (tinea capitis). But also hormonal disorders that change the pH-value of the skin, sugar and fat-rich nutrition, excessive alcohol consumption, allergy or stress can trigger increased dandruff formation. Fleas or lice can also trigger a severe itching and scaling inflammation of the scalp.
