TLDR Bald areas have lower cell growth, more DNA damage, and increased cell death.
This study investigated the role of cell proliferation, DNA repair, and apoptosis in androgenetic alopecia (AGA). The study found that the bald area of AGA had a lower proliferation rate and increased DNA damage, as evidenced by overexpression of XRCC1. The low levels of APE1 expression with concomitant overexpression of p53 would give the opportunity to an alternative pathway to take place in order to eliminate the damaged cells through apoptosis. The study highlights the role of proliferation, DNA damage, and apoptosis in the pathogenesis of AGA.
99 citations,
June 2005 in “Journal of Cosmetic Dermatology” Hair ages due to genetics and environmental factors, leading to graying and thinning, with treatments available for some conditions.
12 citations,
August 2002 in “Archives of Dermatology” 
19 citations,
June 2002 in “American Journal of Dermatopathology” Apoptosis contributes to hair loss in androgenetic alopecia.
71 citations,
June 2001 in “American Journal of Pathology” The p53 protein helps control hair follicle shrinking by promoting cell death in mice.
2 citations,
June 2001 in “American Journal of Pathology” The document concludes that understanding how hair follicles naturally die and regenerate is important for insights into organ development and could impact health and disease treatment.
60 citations,
June 1997 in “Journal of The American Academy of Dermatology” Apoptosis is crucial for healthy skin and treating skin diseases.
11 citations,
April 2013 in “Journal of Proteomics” Found different proteins in balding and non-balding cells, giving insight into hair loss causes.
17 citations,
January 2010 in “International journal of trichology” A man experienced hair loss from radiotherapy, which can be temporary or permanent depending on radiation dose, with potential treatments available.
13 citations,
March 2017 in “Genomics” Genomic approach finds new possible treatments for hair loss.
218 citations,
January 2013 in “The Lancet Oncology” Chemotherapy causes hair loss by damaging hair follicles and stem cells, with more research needed for prevention and treatment.
1 citations,
May 2017 in “InTech eBooks” Hair loss in Androgenetic alopecia (AGA) is due to altered cell sensitivity to hormones, not increased hormone levels. Hair growth periods shorten over time, causing hair to become thinner and shorter. This is linked to miscommunication between cell pathways in hair follicles. There's also a change in gene expression related to blood vessels and cell growth in balding hair follicles. The exact molecular causes of AGA are still unclear.
