TLDR Treating androgenic alopecia can significantly increase hair thickness, especially in males, with hair color and scalp location also affecting hair diameter.
In this study from 2014, 41 patients with androgenic alopecia were treated for six months and their hair diameter changes were compared to 41 age and sex-matched healthy individuals. The mean hair diameter in the patient group increased significantly from 0.052±0.008 to 0.055±0.008 m, 6 months later (p = 0.03), while there was no significant change in the control group. The increase in hair diameter was significantly more in male patients, despite the mean hair diameter being higher in female patients. The study also found that hair color and location on the scalp played significant roles in hair diameter. Light-brown hairs had a significantly higher mean diameter than dark-brown hairs in the patient's thinnest samples.
76 citations,
July 2011 in “Clinical, Cosmetic and Investigational Dermatology” The document concludes that proper diagnosis and FDA-approved treatments for different types of hair loss exist, but treatments for severe cases often fail and future improvements may focus on hair follicle stem cells.
67 citations,
February 2009 in “Journal of Dermatology” 
91 citations,
January 2009 in “International Journal of Trichology” Different hair evaluation methods have their own pros and cons, and using multiple methods together is best for accurate hair loss diagnosis and tracking.
41 citations,
December 2008 in “International Journal of Dermatology” South Korean women with hair loss have lower hair density and thickness compared to healthy women.
72 citations,
March 2005 in “British Journal of Dermatology” AGA can occur in children with family history; early diagnosis and treatment important.
1113 citations,
August 1999 in “The New England Journal of Medicine” Hair follicle biology advancements may lead to better hair growth disorder treatments.
5 citations,
March 2019 in “Dermatologic Clinics” New treatments for hair loss show promise, but require more research on long-term effects and proper dosing.
December 2015 in “Journal of Psoriasis and Psoriatic Arthritis” A patient experienced long-lasting hair loss after using acitretin for psoriasis.
July 2013 in “DeckerMed Family Medicine” The document's conclusion cannot be provided because the document is not readable or understandable.
July 2013 in “DeckerMed Medicine” The document's conclusion cannot be provided because the document is not readable or understandable.
2 citations,
February 2009 in “Journal of Evidence-Based Medicine” No treatment showed significant long-term hair growth benefits for alopecia areata.
