Many factors cause wrinkle formation. They are generally classified as intrinsic causes and extrinsic causes:
Intrinsic causes of wrinkle include:
- reactive oxygen species and free radicals – free radical theory of skin aging
- crosslinking of biomacromolecules
- by glycation
- by ROS/free radicals
- collagen and elastin fiber damage
- DNA damage and mutation
- nuclear DNA damage
- mitochondria DNA damage
- mitochondria damage and reduced cellular energy production
- genetics
- telomere length shortening and cellular senescence
- chronic inflammaging
- reduced dermal stem cell function and activity – the stem cell theory of skin aging
- dehydration
- extracellular matrix ground substance – decreased proteoglycan and glycosaminoglycan
- epidermal-dermal junction structural changes – reduced barrier function
- reduced epidermal cell renewal and skin homeostasis functionality
- decreased functionality of the natural antioxidant system of the skin
- hormone theory of skin aging
- mechanical causes
- facial muscle movement
- gravity
- facial bone aging
Extrinsic causes of wrinkle include:
- sun exposure
- smoking
- diet (deficiency in antioxidants and anti-inflammatory diet)
- pollutions
- stress
- drug