Abstract
Androgenetic alopecia (AGA) is the most common cause of hair loss. Several FDA approved medications are available but offer limited results. Studies have shown that the endocannabinoid system (ECS) is a key player in hair follicle cell growth. The ECS cannabinoid type one (CB1) receptors are well expressed in the hair follicle cells. Cannabidiol (CBD) is a negative allosteric modulator of the CB1 receptor and has been shown to result in hair shaft elongation. In addition, the hair follicle cycle phases are controlled by the ECS vanilloid receptor-1 (TRPV1). CBD has also been shown to increase Wnt signaling pathways that are involved in the differentiation of dermal progenitor cells into new hair follicles and maintaining the anagen phase of the hair cycle. The effects of CBD on hair growth are dose dependent and higher doses may result in premature entry into the catagen phase via a receptor known as vanilloid receptor-4 (TRPV4). Topical application of CBD reaches hair follicles where it is a CB1 negative modulator, and TRPV1, and TRPV4 agonist. A study was done of 35 subjects with AGA using a once daily topical hemp oil formulation, averaging about 3-4 mg per day of CBD and minimal amounts of other cannabinoids for six months. A hair count of the greatest area of alopecia was carried out before treatment and again after six months. The results revealed that men did slightly better than women, and the vertex area did better than the temporal areas. On average there was statistically significant 93.5% increase in hair after 6 months. All subjects had some regrowth. There were no reported adverse effects. Since the CBD works through novel mechanisms different from finasteride and minoxidil it can be used in conjunction with these current drugs and would be expected to have synergistic effects.
