eMedicine Specialties > Dermatology > Diseases of the Adnexa

Androgenetic Alopecia

Author: Robert P Feinstein, MD, Associate Clinical Professor, Department of Dermatology, Columbia University College of Physicians and Surgeons
Contributor Information and Disclosures

Updated: Jan 22, 2009

Introduction

Background

Androgenetic alopecia is an extremely common disorder affecting both men and women. The incidence is generally considered to be greater in males than females, although some evidence suggests that the apparent differences in incidence may be a reflection of different expression in males and females.

Pathophysiology

This genetically determined disorder is progressive through the gradual conversion of terminal hairs into indeterminate hairs and finally to vellus hairs. Patients have a reduction in the terminal-to-vellus hair ratio, normally at least 2:1. Following miniaturization of the follicles, fibrous tracts remain. Patients with this disorder usually have a typical distribution of hair loss.

Frequency

International

This is an extremely common disorder that affects roughly 50% of men and perhaps as many women older than 40 years. As many as 13% of premenopausal women reportedly have some evidence of androgenetic alopecia. However, the incidence increases greatly in women following menopause, and, according to one author, it may affect 75% of women older than 65 years.

Mortality/Morbidity

This is essentially a cosmetic disorder. Other than affecting the patient psychologically,1 the disorder is significant only in that it allows ultraviolet light to reach the scalp and, thus, increases the amount of actinic damage. Males with androgenetic alopecia may have an increased incidence of myocardial infarction.2 An increase in benign prostatic hypertrophy has also been associated.3 If these associations are proven conclusively, this disorder will be of greater clinical significance.

Race

The incidence and the severity of androgenetic alopecia tend to be highest in white men, second highest in Asians and African Americans, and lowest in Native Americans and Eskimos.

Age

Almost all patients have an onset prior to age 40 years, although many of the patients (both male and female) show evidence of the disorder by age 30 years.

Clinical

History

The onset is gradual. Men present with gradual thinning in the temporal areas, producing a reshaping of the anterior part of the hairline. For the most part, the evolution of baldness progresses according to the Norwood/Hamilton classification of frontal and vertex thinning. Women usually present with diffuse thinning on the crown. Bitemporal recession does occur in women but usually to a lesser degree than in men. In general, women maintain a frontal hairline.4

Physical

In both males and females with androgenetic alopecia, the transition from large, thick, pigmented terminal hairs to thinner, shorter, indeterminate hairs and finally to short, wispy, nonpigmented vellus hairs in the involved areas is gradual. As the disorder progresses, the anagen phase shortens with the telogen phase remaining constant. As a result, more hairs are in the telogen phase, and the patient may notice an increase in hair shedding. The end result can be an area of total denudation. This area varies from patient to patient and is usually most marked at the vertex.

Women with androgenetic alopecia generally lose hair diffusely over the crown. This produces a gradual thinning of the hair rather than an area of marked baldness. The part is widest anteriorly. The frontal hairline is often preserved in women with this disorder, whereas men note a gradual recession of the frontal hairline early in the process.

Causes

Androgenetic alopecia is a genetically determined condition. In 2008, 95 families were studied genetically, and the locus with strongest evidence for linkage to androgenetic alopecia was the 3q26 site on the X chromosome.5
 
Androgen is necessary for progression of the disorder, as it is not found in males castrated prior to puberty. The progression of the disorder is stopped if postpubertal males are castrated. Androgenetic alopecia is postulated to be a dominantly inherited disorder with variable penetrance and expression. However, it may be of polygenic inheritance. It has been noted that follicles from balding areas of persons with androgenetic alopecia are able to produce terminal hairs when implanted into immunodeficient mice.6 This suggests that systemic or external factors may play a role in this disorder.

As reported in 2005, it was noted in adult mouse skin that the hedgehog (Hh) family of intercellular signaling proteins can stimulate the transition from the resting (telogen) state to the growth phase (anagen) of the hair cycle.7 Whether this will be helpful in the treatment of androgenetic alopecia remains to be seen.

More on Androgenetic Alopecia

Overview: Androgenetic Alopecia
Differential Diagnoses & Workup: Androgenetic Alopecia
Treatment & Medication: Androgenetic Alopecia
Follow-up: Androgenetic Alopecia
References
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References

  1. Stough D, Stenn K, Haber R, et al. Psychological effect, pathophysiology, and management of androgenetic alopecia in men. Mayo Clin Proc. Oct 2005;80(10):1316-22. [Medline].

  2. Lesko SM, Rosenberg L, Shapiro S. A case-control study of baldness in relation to myocardial infarction in men. JAMA. Feb 24 1993;269(8):998-1003. [Medline].

  3. Oh BR, Kim SJ, Moon JD, et al. Association of benign prostatic hyperplasia with male pattern baldness. Urology. May 1998;51(5):744-8. [Medline].

  4. Ludwig E. Classification of the types of androgenetic alopecia (common baldness) occurring in the female sex. Br J Dermatol. Sep 1977;97(3):247-54. [Medline].

  5. Hillmer AM, Flaquer A, Hanneken S, et al. Genome-wide scan and fine-mapping linkage study of androgenetic alopecia reveals a locus on chromosome 3q26. Am J Hum Genet. Mar 2008;82(3):737-43. [Medline].

  6. Krajcik RA, Vogelman JH, Malloy VL, Orentreich N. Transplants from balding and hairy androgenetic alopecia scalp regrow hair comparably well on immunodeficient mice. J Am Acad Dermatol. May 2003;48(5):752-9. [Medline].

  7. Paladini RD, Saleh J, Qian C, Xu GX, Rubin LL. Modulation of hair growth with small molecule agonists of the hedgehog signaling pathway. J Invest Dermatol. Oct 2005;125(4):638-46. [Medline].

  8. Ahouansou S, Le Toumelin P, Crickx B, Descamps V. Association of androgenetic alopecia and hypertension. Eur J Dermatol. May-Jun 2007;17(3):220-2. [Medline].

  9. Su LH, Chen TH. Association of androgenetic alopecia with smoking and its prevalence among Asian men: a community-based survey. Arch Dermatol. Nov 2007;143(11):1401-6. [Medline].

  10. Headington JT, Novak E. Clinical and histological studies of male pattern baldness treated with topical minoxidil. Curr Ther Res Clin Exp. 1984;36:1098-106.

  11. Olsen EA, Dunlap FE, Funicella T, et al. A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men. J Am Acad Dermatol. Sep 2002;47(3):377-85. [Medline].

  12. Rittmaster RS. Finasteride. N Engl J Med. Jan 13 1994;330(2):120-5. [Medline].

  13. Rogers NE, Avram MR. Medical treatments for male and female pattern hair loss. J Am Acad Dermatol. Oct 2008;59(4):547-66; quiz 567-8. [Medline].

  14. Hamilton JB. Patterned loss of hair in man; types and incidence. Ann N Y Acad Sci. Mar 1951;53(3):708-28. [Medline].

  15. Kaufman KD. Androgen metabolism as it affects hair growth in androgenetic alopecia. Dermatol Clin. Oct 1996;14(4):697-711. [Medline].

  16. Muller SA. Alopecia: syndromes of genetic significance. J Invest Dermatol. Jun 1973;60(6):475-92. [Medline].

  17. Olsen EA. Androgenetic alopecia. In: Olsen EA ed. Disorders of Hair Growth: Diagnosis and Treatment. New York, NY: McGraw-Hill; 1994:257-83.

  18. Olsen EA, Messenger AG, Shapiro J, et al. Evaluation and treatment of male and female pattern hair loss. J Am Acad Dermatol. Feb 2005;52(2):301-11. [Medline].

  19. Otberg N, Finner AM, Shapiro J. Androgenetic alopecia. Endocrinol Metab Clin North Am. Jun 2007;36(2):379-98. [Medline].

  20. Shapiro J, Price VH. Hair regrowth. Therapeutic agents. Dermatol Clin. Apr 1998;16(2):341-56. [Medline].

  21. Sperling LC. Evaluation of hair loss. Curr Probl Dermatol. 1996;8:97-136.

  22. Sperling LC, Lupton GP. Histopathology of non-scarring alopecia. J Cutan Pathol. Apr 1995;22(2):97-114. [Medline].

  23. Stern Rl, Heymann WR. Androgenetic alopecia. Clin Dermatol. 1997;2(32):1-6.

  24. Venning VA, Dawber RP. Patterned androgenic alopecia in women. J Am Acad Dermatol. May 1988;18(5 Pt 1):1073-7. [Medline].

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Further Reading

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Keywords

androgenetic alopecia, common baldness, familial baldness, hereditary baldness, male pattern baldness, female pattern baldness, pattern baldness, hair loss, androgenic alopecia

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Contributor Information and Disclosures

Author

Robert P Feinstein, MD, Associate Clinical Professor, Department of Dermatology, Columbia University College of Physicians and Surgeons
Robert P Feinstein, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, Noah Worcester Dermatological Society, and Phi Beta Kappa
Disclosure: Nothing to disclose.

Medical Editor

Leonard Sperling, MD, Chair, Professor, Department of Dermatology, Uniformed Services University of the Health Sciences
Leonard Sperling, MD is a member of the following medical societies: American Academy of Dermatology
Disclosure: Nothing to disclose.

Pharmacy Editor

David F Butler, MD, Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic
David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa
Disclosure: 3M Pharmaceutical Grant/research funds Other; Graceway Pharmaceuticals Grant/research funds Other

Managing Editor

Edward F Chan, MD, Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania School of Medicine
Edward F Chan, MD is a member of the following medical societies: American Academy of Dermatology, American Society of Dermatopathology, and Society for Investigative Dermatology
Disclosure: Nothing to disclose.

CME Editor

Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University
Catherine Quirk, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology
Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology
Disclosure: Nothing to disclose.

 
 
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