Growing old: Do women and men age differently?

Aging of the head and especially the face has been studied intensively, yet questions remain about the timing and rates of aging throughout adulthood and about the extent to which aging differs between men and women. Here we address these issues by developing statistical models of craniofacial aging to describe and compare aging through the life course in both sexes. We selected cranial surface meshes from 254 females and 252 males, aged from 20 to 90 years from the Headspace project, Liverpool, UK. Sixteen anatomical landmarks and 59 semilandmarks on curves and surfaces were used to parameterize these. Modes and degrees of aging throughout adulthood were assessed and compared among sexes using Procrustes-based geometric morphometric methods. Regression analyses of form through the whole age range indicate that age accounts for a small proportion of total variance in both sexes, but form is significantly related to age and males and females age in significantly different ways. Further analyses indicate that aging differs in character, timing, and rates in both sexes between early and later phases of adulthood. Sexual differences in aging are evident in the early and later phases of adulthood. The study adds to knowledge of the aging of adult craniofacial form and sexual dimorphism. It is based on a local population and so the findings are directly applicable to that population. Further studies are needed to assess generalizability and provide better data on population differences to facilitate clinical assessment and treatment planning.

3D Modeling of craniofacial ontogeny and sexual dimorphism in children.

BACKGROUND: The range of normal variation of growth and development of the craniofacial region is of direct clinical interest but incompletely understood. Here we develop a statistical model of craniofacial growth and development to compare craniofacial ontogeny between age groups and sexes and pilot an approach to modeling that is relatively straightforward to apply in the context of clinical research and assessment. METHODS: The sample comprises head surface meshes captured using a 3dMD five-camera system from 65 males and 47 females (range 3-20 years) from the Headspace project, Liverpool, UK. The surface meshes were parameterized using 16 anatomical landmarks and 59 semilandmarks on curves and surfaces. Modes and degrees of growth and development were assessed and compared among ages and sexes using Procrustes based geometric morphometric methods. RESULTS: Regression analyses indicate that 3-10 year olds undergo greater changes than 11-20 year olds and that craniofacial growth and development differs between these age groups. The analyses indicate that males extend growth allometrically into larger size ranges, contributing substantially to adult dimorphism. Comparisons of ontogenetic trajectories between sexes find no significant differences, yet when hypermorphosis is accounted for in the older age group there is a significant residual sexual dimorphism. CONCLUSIONS: The study adds to knowledge of how adult craniofacial form and sexual dimorphism develop. It was carried out using readily available software which facilitates replication of this work in diverse populations to underpin clinical assessment of deformity and the outcomes of corrective interventions.