Hair ageing is not just external - it starts deep within the follicle, especially in two key regions - The hair matrix, where new hair cells are formed and the bulge area, home to follicular stem cells and melanocyte stem cells (which produce pigment). Over time, oxidative stress, DNA damage, and reduced stem cell renewal begin to impair both hair structure and colour, setting the stage for visible signs of ageing: thinning, brittleness, and greying.

Reactive oxygen species (ROS), generated both internally (mitochondrial activity, inflammation) and externally (UV exposure, pollution), are central to hair ageing. In melanocytes (the pigment-producing cells), ROS damage mitochondria and DNA, disrupting melanin synthesis. Enzymes like tyrosinase, essential for producing eumelanin and pheomelanin, become less active or dysfunctional under oxidative stress. This leads to melanocyte apoptosis (cell death), and the eventual depletion of pigment - resulting in grey or white strands. In hair matrix keratinocytes, oxidative stress also slows cell proliferation, resulting in thinner hair shafts and a slower growth rate.

Hair gets its color from melanin, transferred from melanocytes to keratinocytes during hair formation. But melanocytes rely on a constant supply of melanocyte stem cells from the follicular bulge. With age these stem cells lose their regenerative capacity., some migrate abnormally or differentiate prematurely and others are lost entirely due to epigenetic changes or inflammation. Once depleted, melanocytes are no longer replenished, leading to permanent greying. This process is accelerated by chronic stress, inflammation, smoking, or nutritional deficiencies (especially copper, vitamin B12, and folate).

Ageing also affects the quality and composition of the hair fibre itself. Reduced production of keratin and lipids makes hair coarser, more porous, and prone to breakage. Fewer disulfide bonds (which maintain hair’s strength and elasticity) develop, weakening the hair shaft. Sebum production from sebaceous glands decreases, reducing natural lubrication and shine. The cumulative result: duller, drier, thinner hair with reduced volume and resilience.

Age-related hormonal shifts, especially involving androgens like DHT (dihydrotestosterone), can trigger follicular miniaturization, reducing the diameter and length of hair strands, shorten the anagen (growth) phase and inhibit stem cell activation, further limiting hair regeneration. This process—seen in both men and women—can overlap with greying, amplifying visible signs of ageing on the scalp.