Hair Loss: Hair Shaft Defects
People with monilethrix have diffuse hair loss. Most frequently the hair loss is at the back of the scalp and neck and can leave the front of the head relatively unaffected. Monilethrix can also affect hair in other regions of the body.
Monilethrix most often occurs in childhood but young adults can also develop it. It is a genetically inherited disease and can run in families, although family members may be affected to different degrees of severity. The severity of monilethrix can also change with the seasons. It is often worse in winter and improves in summer. Monilethrix may spontaneously improve, although many people have monilethrix all their lives.
Overprocessing, cuticle stripping, and bubble hair
Overprocessing the hair is by far the most common cause of physical hair damage. Perming, straightening, bleaching, and dyeing the hair all involve harsh chemicals that can significantly affect the integrity of hair fiber. Using these cosmetic approaches too frequently or inappropriately can lead to irreversible damage to the hair fiber. The more hair fiber is damaged by these processes, the weaker it will be and the more likely it will break off.
The hair cuticle is a very strong outer sleeve of dead and highly keratinized cells that overlap each other like fish scales along the length of the hair fiber. The cuticle helps protect the softer inner cortex structure of the hair fiber from damage. The overlapping scales of the cuticle may become damaged and "flake up" if they are exposed to too much processing.
For perms, straighteners, bleaches, and dyes to work the cuticle has to be opened up so that other chemicals can get to the hair cortex and either rearrange the chemical bonds in the hair structure, as with perms and straighteners, or to remove or add hair pigment, as with bleaching and dyeing. If the chemicals to open the cuticle are applied for too long, in an unsuitably high concentration, or too frequently, the cuticle may be irreversibly damaged and even stripped away completely.
When this happens the softer cortex is exposed to the environment. The cortex does not have the same properties of the cuticle. It has a rough surface, so at this stage the hair can look dull, dry, and frizzy. Chemicals in shampoos, water, and polluted air, combined with UV light exposure, can all contribute to further damage and weakening of the hair cortex. Eventually, the hair may become so weak that it splits or breaks off completely. More usually, this splitting and breakage occurs to old hair, that is, toward the end of the hair fiber.