Age-Associated Differences in Facial Skin Structure in Chinese Women: a Cross-Sectional Study

Facial skin aging is a process leading to structural degradation and visible phenotypical changes. Prior studies examined age-related skin parameters and suggested accelerated changes occurring in the early 30s, yet precise timing remains insufficiently defined, and few assessed their interrelationships across facial zones in Chinese populations. In this cross-sectional study, 547 Chinese women aged 18–65 years from three cities underwent facial skin assessments using two-photon microscopy (TPM) and high-frequency ultrasound, collecting structural parameters, biophysical measures and clinical phenotypes. Age-related trends were analyzed, and principal component analysis (PCA) was applied to structural parameters in the cheek and eye corner zones to explore associations with surface-level characteristics via multiple linear regression. Key age-associated structural differences included decreased second harmonic generation to autofluorescence aging index of dermis and dermal density, increased elastin-to-collagen ratio, and dermo-epidermal junction flattening becoming prominent in the 36–45-year age group and beyond. Biophysical measurements, such as skin elasticity, hydration and lightness declined with age, while phenotypical aging signs (wrinkle and pigmentation severity) increased. PCA-derived principal component 1 (PC 1 ) represented dermal integrity and echogenicity, while principal component 2 (PC 2 ) reflected the elastin-to-collagen profile, explaining 46–48% of the variance of skin aging in our study population. Principal component (PC) logistic regression showed positive association of PC 1 with favorable skin characteristics such as skin elasticity, hydration and lightness, and lower severity of phenotypical aging signs, including wrinkles and hyperpigmentation ( p < 0.05). The inverse was true for PC 2 ( p < 0.05). This study provides a comprehensive evaluation of age-associated differences in facial skin parameters in Chinese women, revealing structural underpinnings of visible aging signs. The findings highlight zone-specific aging patterns and support the utility of TPM and ultrasound in integrated imaging techniques for dermatological aging assessments and personalized aesthetic interventions.