Age & hormones, 2 factors influencing the hair cycle

- Age

- Hormones

The influence of age on the hair cycle

The influence of hormones on the hair cycle

Hair changes from puberty onwards, with the massive arrival of male and female hormones in the blood.

The life cycle of the hair is dictated by the influence of these hormones. These are produced by the endocrine gland and are transported in the blood. They will attach themselves to the target cells, in this case the hair roots, which will pick up the hormone's signal and react accordingly.

There are two types of hormones: male hormones or androgens, which include testosterone, and female hormones or estrogens, including progesterone.

These hormones play a different role in the body and particularly in the hair.

Female hormones or estrogens participate in hair growth by slowing down its growth and prolonging the anagen phase.

On the other hand, male hormones or androgens accelerate the hair cycle. Strictly speaking, it is not androgens alone that cause hair loss. It is actually a chemical reaction, DHT, which is caused by the meeting of androgens with 5-alpha reductase, an enzyme of the scalp. DHT accelerates the hair production cycle to such an extent that hair follicles become saturated and produce only shorter and thinner hair until they are exhausted. They end up producing only a fine fuzz and, eventually, nothing. The inactive follicles then retract into the dermis and the skin becomes smooth.

Both men and women secrete male and female hormones, but in different quantities, so women also produce androgens, but in quantities 20 times lower than men.

This is why women, unless they have a particular disease or hormonal disorder, never go bald. However, they may experience increased hair loss or a change in hair texture due to a decrease in the production of female hormones at the time of menopause.

Good to know

Motherhood also influences the life cycle of hair. During pregnancy, in the2nd and3rd trimesters, a woman's body secretes more female hormones, so 90% of hair is in the anagen phase. It is not uncommon for a woman to lose a lot of hair after giving birth, or "post-partum" hair loss, once her estrogen levels have been regulated and stop "boosting" hair growth.