The Science of Skin Ageing — Intrinsic vs Extrinsic Factors and How to Address Both

Last updated: 5 March 2026

Medically reviewed by the clinical team at Axiom Aesthetics. Our practitioners apply current dermatological science to every treatment plan, ensuring interventions target the specific ageing pathways affecting each patient.

Skin ageing is not a single process — it is the result of multiple biological pathways acting simultaneously, each contributing different visible changes. Understanding the distinction between intrinsic ageing (the genetic, time-dependent process) and extrinsic ageing (caused by environmental factors) is fundamental to choosing the right preventive strategies and treatments.

At Axiom Aesthetics, we take a science-first approach to anti-ageing, tailoring treatments to address each patient’s specific ageing pathways. Here is a deep dive into what actually happens to skin as it ages — and what you can do about it.

Intrinsic Ageing: The Biological Clock

Intrinsic ageing — also called chronological or constitutional ageing — is the natural, genetically programmed decline in skin function that occurs over time. It begins in our mid-20s but may not become visible until decades later. This process is driven by several key mechanisms:

Telomere Shortening

Every time a cell divides, the protective caps on chromosome ends (telomeres) shorten slightly. When telomeres reach a critical length, the cell enters senescence — it stops dividing and begins releasing pro-inflammatory molecules called senescence-associated secretory phenotype (SASP) factors. These senescent cells accumulate with age, contributing to chronic low-grade inflammation (“inflammaging”) that degrades the skin’s structural matrix.

Declining Cellular Energy (Mitochondrial Dysfunction)

Mitochondria — the energy powerhouses of cells — become less efficient with age, producing more reactive oxygen species (ROS) and less ATP (cellular energy). Skin cells with reduced energy budgets produce less collagen, repair DNA damage more slowly, and turn over less efficiently. This manifests as thinner, less resilient skin with slower healing capacity.

Reduced Hormone Levels

Oestrogen, testosterone, growth hormone, and DHEA all decline with age. Oestrogen, in particular, has a profound effect on skin — it stimulates collagen and hyaluronic acid production, maintains skin thickness, and supports wound healing. The sharp decline in oestrogen during menopause leads to a 30% loss of collagen in the first five years post-menopause (Source: American Journal of Clinical Dermatology, 2022).

Collagen and Elastin Degradation

From age 25, collagen production decreases by approximately 1-1.5% per year. Simultaneously, the existing collagen becomes increasingly cross-linked and fragmented, losing its structural integrity. Elastin fibres calcify and fragment, reducing skin’s ability to snap back after stretching. By age 80, the dermis may contain 75% less collagen than at age 25.

Reduced Glycosaminoglycan Production

Hyaluronic acid — which holds up to 1,000 times its weight in water — diminishes with age, leading to progressive dehydration and loss of plumpness. The skin’s natural moisturising factor (NMF) also declines, further compromising hydration.

Extrinsic Ageing: Environmental Assault

Extrinsic ageing accounts for up to 80% of visible facial ageing and is largely preventable. The primary factors include:

Photoageing (UV Damage)

Ultraviolet radiation is the single greatest contributor to premature skin ageing. UV exposure damages skin through multiple mechanisms:

• UVB (280-320nm): Primarily damages the epidermis, causing sunburn, DNA mutations, and disruption of melanocyte function (pigmentation irregularities)
• UVA (320-400nm): Penetrates deeper into the dermis, generating ROS that degrade collagen and elastin through activation of matrix metalloproteinases (MMPs). UVA is present year-round, penetrates glass, and is the primary driver of photoageing.
• Infrared-A and visible light: Emerging research shows these wavelengths also contribute to free radical generation and collagen breakdown, though to a lesser extent than UV

Photoaged skin shows coarse wrinkles, irregular pigmentation, loss of elasticity (solar elastosis), rough texture, and telangiectasia (visible blood vessels). The difference between photoaged and intrinsically aged skin is dramatically illustrated by comparing sun-exposed areas (face, hands) with sun-protected areas (inner arms, buttocks).

Pollution

Particulate matter (PM2.5 and PM10), polycyclic aromatic hydrocarbons, and volatile organic compounds penetrate the skin barrier and generate oxidative stress. Studies show that long-term exposure to urban air pollution is associated with a 20% increase in pigmentation spots and accelerated formation of nasolabial folds (Journal of Investigative Dermatology, 2020).

Lifestyle Factors

• Smoking: Reduces blood flow to the skin by 40%, accelerates collagen breakdown, and triggers MMP production. Smokers develop wrinkles an average of 10-15 years earlier than non-smokers.
• Alcohol: Causes chronic dehydration, dilates blood vessels (contributing to rosacea and redness), depletes vitamins A and C, and impairs liver function needed for detoxification.
• Sleep deprivation: Growth hormone — essential for cellular repair — is primarily released during deep sleep. Chronic poor sleep reduces collagen production, impairs barrier function, and accelerates cellular ageing.
• Stress: Cortisol increases sebum production, breaks down collagen, and triggers inflammatory pathways. Chronic stress shortens telomeres independently of other factors.
• Diet: Advanced glycation end products (AGEs) — formed when sugars bind to proteins — accumulate in the skin, cross-linking collagen and making it stiff and brittle. High-glycaemic diets accelerate this process.

Treatments That Target Intrinsic Ageing

At Axiom Aesthetics, we offer several treatments that directly address the mechanisms of intrinsic ageing:

• PRF/PRP therapy: Delivers concentrated growth factors that stimulate fibroblast activity and collagen production
• Polynucleotide therapy: Provides DNA building blocks that support cellular repair and regeneration
• Skin boosters (Profhilo): Replenish hyaluronic acid that the skin can no longer produce sufficiently
• Radiofrequency therapy: Heats the dermis to stimulate neocollagenesis — new collagen production
• Peptide mesotherapy: Delivers signal peptides that instruct cells to resume youthful production rates
• LED light therapy: Red light (630-660nm) stimulates mitochondrial function, increasing cellular energy and collagen synthesis

Treatments That Target Extrinsic Ageing

• Chemical peels: Remove photoaged surface cells, stimulate renewal, and reduce pigmentation
• Laser treatments: Target sun-induced pigmentation, vascular damage, and stimulate deep collagen remodelling
• IPL therapy: Addresses pigmentation irregularities and visible blood vessels caused by UV damage
• Microneedling: Creates controlled injury that triggers the wound-healing cascade, remodelling damaged tissue
• Medical-grade skincare: Retinoids, vitamin C, and niacinamide address oxidative damage and stimulate repair pathways

Prevention: The Most Effective Anti-Ageing Strategy

While treatments can reverse existing damage, prevention remains the most cost-effective approach. Our clinical team recommends:

• Daily broad-spectrum SPF 50: The single most impactful anti-ageing step. Reapply every 2 hours when outdoors.
• Topical retinoid: The most evidence-backed anti-ageing ingredient. Start with a low concentration and build up.
• Antioxidant serum: Vitamin C (L-ascorbic acid) at 10-20% neutralises free radicals and supports collagen.
• Adequate sleep: 7-9 hours per night to maximise growth hormone release.
• Balanced diet: Rich in antioxidants, omega-3 fatty acids, and low in refined sugars.
• Stress management: Regular exercise, meditation, or other stress-reduction practices.
• No smoking: The single most damaging extrinsic factor after UV exposure.

Personalised Anti-Ageing at Axiom Aesthetics

Understanding the science behind skin ageing allows us to create targeted, effective treatment plans. Rather than a one-size-fits-all approach, we identify which ageing pathways are most active in your skin and select treatments that specifically address those mechanisms.

Book your comprehensive skin assessment at Axiom Aesthetics and discover a science-backed approach to ageing gracefully.

References: Rittie, L. & Fisher, G.J. (2015). “Natural and sun-induced aging of human skin.” Cold Spring Harbor Perspectives in Medicine, 5(1), a015370. Krutmann, J. et al. (2021). “The exposome and skin aging.” Experimental Dermatology, 30(S1), 11-16. Farage, M.A. et al. (2022). “Intrinsic and extrinsic factors in skin ageing.” American Journal of Clinical Dermatology, 23(2), 143-160. Hughes, M.C. et al. (2013). “Sunscreen and prevention of skin aging.” Annals of Internal Medicine, 158(11), 781-790.