Premature hair loss or balding has many causes, but the most common is androgenic alopecia, also called male or female pattern baldness. In this condition, the presence of extra hormones, testosterone and DHT, affect the growing cycle of hair, causing more than the usual shedding of hair and death of hair follicles. Medical professionals estimate that at least 90% of cases of early hair loss are due to this cause.
Hair loss in women, particularly when they reach their late 30s or 40s and begin to produce less estrogen, can be tied to this hormone decline. Women who have been pregnant may have experienced especially thick and lustrous hair during their pregnancy due to extra estrogen. When levels begin to decline, hair growth slows, and some follicles may die. Estrogen therapy can slow this hair loss, but there are some downsides to using it. It is linked to a much higher risk for certain cancers, and hormone replacement therapy is used with far less frequency than it once was.
Scientists also point to many medications that can result in premature hair loss. For instance, thyroid hormone can cause hair to fall out, though a lack of thyroid hormone can also create hair loss. Certainly medications, like those used for chemotherapy, cause temporary hair loss as well, although it typically regrows after the treatment is stopped. Certain medications for mood disorders and seizures, like carbamazepine, used often by people with bipolar disorder, can cause the hair to fall out as well, as can a number of antidepressants. Medications that list hair loss as a side effect do not necessarily mean that it is assured or will be significant, merely that there is a potential for it.
Malnutrition may affect hair growth and result in premature hair loss. When a person is severely malnourished or has a condition like irritable bowel syndrome, the body either doesn’t have access to or can’t absorb necessary vitamins and minerals. Baldness can be a result, even in very young children. Again, this hair loss doesn’t necessarily cause the death of hair follicles, and if adequate nutrition is achieved, the hair loss can be temporary.
Another condition that can result in patchy baldness is trichotillomania, a disorder marked by a compulsive desire to pull out the hair. Trichotillomania is considered similar to obsessive-compulsive disorder and can respond to treatment with certain antidepressants and with cognitive behavioral therapy. While it continues, excessive hair pulling can damage hair follicles to the point where they no longer function. It is best to treat this condition early when possible to avoid such damage.