There are two major mechanisms responsible for the onset of wrinkles: depletion of the skin’s collagen support network, and repetitive facial expressions that create creases in the skin. In many cases, these two factors can also interplay for an exacerbated effect.
The depletion of collagen can be very frustrating for patients. When we are young, our skin is filled with collagen fibers that keep the skin elastic and provide it with support. As we age, various factors destroy some of the collagen fibers and cause the remaining ones to shrink. This leads to skin that is thinner and more likely to sag.
Repetitive facial expressions, like smiling and frowning, also contribute to wrinkle formation by causing the skin to crease in the same place over and over. Eventually, the creases can become pronounced-enough that even the smallest movement of facial muscles can make us look tired or angry.