Quantitative mapping of human hair graying and reversal in relation to life stress.

eLife 2021; 10: e67437 DOI: 10.7554/eLife.67437

Commentary

It is generally believed that gray hair on the head is irreversible and changes based on psychological stress.

In this study, we developed an approach to profile hair pigmentation patterns (HPPs) along individual human hair trunks to generate quantifiable physical timescales of rapid graying transitions.

The resulting method is used to quantitatively define the reversibility of human gray, showing white/gray hair regaining pigmentation naturally across gender, ethnicity, age, and body part. Molecularly, gray hair upregulates proteins associated with energy metabolism, mitochondria, and antioxidant defenses, and by combining HPP profiling and single hair proteomics, we also report hair graying and reversal that may occur in parallel with psychological stressors.

To generalize these observations, we developed computational simulations, suggesting a threshold-based mechanism for the transient reversibility of graying.

What emerges from this study is a new way to quantitatively map the recent life history of HPPs, providing an opportunity to longitudinally examine the effects of recent life exposures on human biology.