(29th June 2021) In a STUDY titled ‘Quantitative mapping of human hair greying and reversal in relation to life stress’ published in eLife on 22nd June, research conducted at Columbia University showed the development of a new method for capturing highly detailed images of tiny slices of human hairs to quantify the extent of pigment loss (greying) in each of those slices, producing quantifiable physical timescales of rapid greying transitions. The study also measured thousands of proteins in the hairs and showed how protein levels changed over the length of each hair to better understand how stress causes grey hair. The study further showed that hair colour has the potential to be restored when stress is eliminated.
In this research, individual hairs from 14 male and female volunteers (x 100 hairs for each volunteer) were analysed. The results were compared with each volunteer’s stress diary, in which individuals were asked to review their calendars and rate each week’s level of stress. The investigators immediately noticed that some grey hairs naturally regain their original colour, when stress is reduced, which had never been quantitatively documented.
Changes in 300 proteins which occurred when hair colour changed were also documented when the researchers developed a mathematical model that suggests stress-induced changes in mitochondria may explain how stress turns hair grey.
Speaking about the research and the findings, Dr Martin Picard, Associate Professor of Behavioural Medicine (in Psychiatry and Neurology) at Columbia University Vagelos College of Physicians and Surgeons and the study’s Senior Author said ‘If you use your eyes to look at a hair, it will seem like it is the same colour throughout unless there is a major transition. Under a high-resolution scanner, you see small, subtle variations in colour, and that is what we are measuring.’
‘Understanding the mechanisms that allow ‘old’ grey hairs to return to their ‘young’ pigmented states could yield new clues about the malleability of human aging in general and how it is influenced by stress. Our data add to a growing body of evidence demonstrating that human aging is not a linear, fixed biological process but may, at least in part, be halted or even temporarily reversed’ continued Dr Picard.
Also speaking about the results, Prof Des Tobin, Full Professor of Dermatological Science, UCD and Director, Charles Institute of Dermatology and one of the Study’s Co-Authors said ‘Hair greying is a visible feature of human biological ageing, which was believed to be largely irreversible (outside of drug interactions) and hitherto has been linked to psychological stress, but only anecdotally.’
‘In this approach to profiling HPPs (Hair Pigmentation Patterns) we show that aligning hair pigmentation patterns with recent reports of psychosocial stress in the hair donors’ lives can reveal striking associations. This method further showed that some white/ grey hairs can naturally regain pigmentation across different sex, ethnicities, age and body regions, which is not something that has been reported in a cohort of healthy individuals before. This method has allowed us to quantifiably define the reversibility of greying in humans’ continued Prof Tobin.
‘Based on our mathematical modelling, we think hair needs to reach a threshold before it turns grey. In middle age, when the hair is near that threshold because of biological age and other factors, stress will push it over the threshold, and it transitions to grey. But we don’t think that reducing stress in a 70-year-old who’s been grey for years will darken their hair or increasing stress in a 10-year-old will be enough to tip their hair over the grey threshold’ continued Dr Picard.
The new method for measuring small changes in hair colouring, as documented in this study, opens up the possibility of using hair pigmentation patterns like tree rings. This could track the influence of past life events on human biology. In the future, monitoring hair pigmentation patterns could provide a way to trace the effectiveness of treatments aimed at reducing stress or slowing the aging process. Understanding how ‘old’ white hairs regain their ‘young’ pigmented state could also reveal new information about the flexibility of human aging more generally.
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