Ask Emily

29 03 2012

Why does our hair thin out as we age? My aunt lost hair in unexpected places as she closed in on her 80th year.

The reasons for hair thinning as we age range from benign but perhaps unwanted processes to serious disease. One reason your hair may seem thinner as you get older is that each individual hair is itself literally thinner because the hair follicle narrows with age. The result is hair with less volume than you may have had before, which seems like thinning. Because thinner also means “breaks more easily,” you may see more hair in your hairbrush or after a shower, but that doesn’t mean your hair is actually falling out.

If your hair is really falling out, the usual cause is an inherited susceptibility to androgens. The official name is androgenetic alopecia (“androgenetic” refers to an inherited susceptibility to androgenic hormones and “alopecia” means hair loss). Most people are aware that men develop this form of hair loss, which we know of more colloquially as “male pattern baldness.” Men and women exhibit different patterns of baldness when these androgens kick in with age, and women tend to lose their hair over the front part of the scalp and have thinning all over. This loss in women also may be related to changes at menopause, and some research suggests that estrogen decline in addition to androgen activity could be involved. A recent study also found that malfunctions in the source cells for hair follicles may also be part of the pathway that leads to androgenetic alopecia.

While the loss itself is not harmful, the appearance that results can be particularly difficult for women, as most people don’t expect it to happen in women, in spite of how common it is. Treatments for androgenetic alopecia in women include use of compounds that block androgens or a compound called minoxidil that circumvents androgen activity and promotes hair growth.

While these common causes of hair thinning are relatively benign in health terms, thinning can also signal something more dire. One common health-related cause of hair loss is thyroid dysfunction. Emotional or physical stress, such as childbirth, major surgery, or severe infection can also elicit a widespread loss of hair weeks or even months after the episode occurs. The loss eventually slows.

Some infectious diseases can cause hair loss, including syphilis, while autoimmune diseases like lupus can also be to blame, although some forms of lupus and associated hair loss may actually improve with age and after menopause. In elderly women, causes of hair loss include pulling out the hair themselves in some cases, known as trichotillomania. Another potential cause of hair loss is giant cell arteritis, which is inflammation of the arteries in the upper body, head, and neck. If a person whose hair is thinning also has been diagnosed with cancer, any hair loss should be closely investigated for the possibility that the cancer has metastasized or migrated to the scalp.

The bottom line with hair loss is that any hair loss that is sudden, occurs in an odd pattern, or that you simply find worrisome justifies a call to a medical professional. As one scientific abstract noted, hair loss particularly in postmenopausal women “warrants close inspection.”

Do you have a question for Emily? Send it to:

By Emily Willingham

Image courtesy of  Wikimedia Commons