Understanding Hair Follicular Units: Each hair follicular unit is comprised of 3-5 terminal hairs. These hairs are nourished by a branching muscle known as the arrector pili muscle (APM). The APM primarily attaches around the main hair follicle and can have varying connections to the surrounding hair follicles.

 

Arrector Pili Muscle in Hair Loss:

 

In MAA: MAA, as well as female pattern hair loss, often witnesses the follicles becoming miniaturized. This miniaturization can either be permanent or have limited reversibility. One consistent observation in these scenarios is the loss of the APM's attachment to the smaller, vellus hair follicles.

 

Comparison to Alopecia Areata: Unlike MAA, in the case of alopecia areata (a potentially reversible hair loss condition), the APM remains connected to the miniaturized hair follicles.

 

Importance of APM Connection: Studies suggest that the continued connection of the APM to the hair follicle might indicate the potential for reversing the hair miniaturization process.

 

New Theories on MAA Progression: A recent hypothesis surrounding the progression of MAA emphasizes the role of the APM. 

 

In the early phases of MAA: The APM still clings to the primary follicle but starts to detach from some of the shrinking secondary follicles within certain follicular units. As more hair follicles shrink and the APM detaches further, individuals often perceive a drop in hair density, describing their hair as "thinning." When the APM loses its connection with all the secondary follicles, and as the primary ones miniaturize and detach, it’s probable that the hair loss becomes permanent.

 

Conclusion: This emerging understanding underscores the critical nature of early intervention in treating MAA. To potentially prevent irreversible hair loss, treatments should ideally begin before the primary hair follicles are lost.