Intrinsic Ageing
The natural, genetically determined ageing process of the skin characterised by gradual decline in collagen and elastin production, thinning of the epidermis, and reduced cell turnover. Intrinsic ageing occurs independently of environmental factors and cannot be fully prevented.
Technical Context
Intrinsic (chronological) ageing affects skin through: reduced cellular proliferation (keratinocyte turnover slows from ~28 days in young skin to >40 days in elderly), decreased collagen synthesis (approximately 1% decline per year after age 30 — fibroblast senescence reduces both collagen production rate and collagen quality), reduced elastin network (degradation without replacement), thinning of dermis and epidermis (reduced ECM and fewer cell layers), decreased vascularity (fewer dermal capillaries), reduced sebaceous gland activity (drier skin), and decline in immune surveillance cells (Langerhans cells). At the molecular level: telomere shortening (limiting cell division capacity), mitochondrial DNA mutations (reducing cellular energy production), accumulation of advanced glycation end-products (AGEs — crosslinking collagen, reducing its flexibility), and altered gene expression (reduced growth factor production). Intrinsic ageing is genetically programmed and cannot be fully prevented, though lifestyle factors (nutrition, sleep, stress management) modulate its rate.