The skin is supported by a dermal scaffold of collagen and elastin. Beginning in your mid-twenties, collagen production declines by roughly 1 percent per year, and elastin loses its ability to recoil. As this scaffold weakens, the skin can no longer bounce back from the thousands of facial expressions you make each day, and creases that were once temporary begin to settle in.
Repeated muscle contraction is the primary driver of dynamic wrinkles. Every time you furrow your brow, squint, or smile, the underlying muscles fold the overlying skin. According to the American Academy of Dermatology, this repetitive motion gradually etches expression lines into the dermis, especially in areas with thinner skin like the forehead, glabella, and crow's feet.
Sun exposure compounds the problem. UV radiation degrades collagen, generates free radicals, and triggers abnormal elastin accumulation, a process called solar elastosis. Combined with smoking, dehydration, and genetics, photodamage is responsible for the majority of premature wrinkles seen in patients under 50.
