From the Research
The catagen phase is a critical transitional stage of hair growth that lasts approximately 2-3 weeks, during which hair follicles shrink and detach from the dermal papilla, causing growth to stop, and is controlled by various hormones and growth factors, particularly androgens and TGF-beta. This phase is characterized by the shortening of the follicle through a process of programmed cell death (apoptosis) in the lower portion of the hair follicle, resulting in the formation of a club hair with a bulbous end that remains anchored in the follicle until it's eventually shed 1. Understanding the catagen phase is essential because disruptions in this cycle can contribute to various hair disorders, including telogen effluvium and alopecia, which can be triggered by stress, medications, and certain medical conditions that prematurely push hairs into the catagen phase, potentially leading to increased hair shedding 2. Some studies have investigated the effects of minoxidil on the catagen phase, suggesting that it can prolong the anagen phase and delay the onset of catagen by activating the β-catenin pathway in human dermal papilla cells 1, while others have explored the use of oral minoxidil as a treatment for hair loss, including androgenetic alopecia, with promising results 3, 4. Key factors that influence the catagen phase include:
- Hormones, such as androgens, which play a crucial role in regulating hair growth and can contribute to hair disorders like androgenetic alopecia 3
- Growth factors, including TGF-beta, which signal the follicle to stop producing new cells and initiate the catagen phase 2
- Apoptosis, or programmed cell death, which occurs in the lower portion of the hair follicle during the catagen phase, leading to the shortening of the follicle and the formation of a club hair 1
- Stress, medications, and certain medical conditions, which can disrupt the normal hair growth cycle and prematurely push hairs into the catagen phase, resulting in increased hair shedding 5.