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Changes in brain morphology have been reported during development, ageing and in relation to different pathologies. Brain morphology described by the shape complexity of gyri and sulci can be captured and quantified using fractal dimension (FD). This measure of brain structural complexity, as well as brain volume, are associated with intelligence, but less is known about the sexual dimorphism of these relationships. In this paper, sex differences in the relationship between brain structural complexity and general intelligence (g) in two diverse geographic and cultural populations (UK and Indian) are investigated. 3D T1-weighted magnetic resonance imaging (MRI) data and a battery of cognitive tests were acquired from participants belonging to three different cohorts: Mysore Parthenon Cohort (MPC); Aberdeen Children of the 1950s (ACONF) and UK Biobank. We computed MRI derived structural brain complexity and g estimated from a battery of cognitive tests for each group. Brain complexity and volume were both positively corelated with intelligence, with the correlations being significant in women but not always in men. This relationship is seen across populations of differing ages and geographical locations and improves understanding of neurobiological sex-differences.

Low socio-economic status is a recognised composite measure made up of income, education and occupational social class, which is a risk factor for poor physical and mental health and late life dementia. Here, we distinguish between components of childhood socioeconomic status to explore their separate influences of childhood and adult occupational social class (OSC), childhood mental ability and education on late life cognitive ability and change trajectories. Cognitive data were collected longitudinally from a sub-sample (N = 478) of the Aberdeen 1936 birth cohort tested on up to 5 occasions between ages 63 and 78 years. Age 11 mental ability scores were available for all participants. We used longitudinal multi-level linear modelling to explore models of cognitive change that distinguished between the possible influences of parental occupation, participants' own occupation as adults, duration of formal education, childhood mental ability and the participants' own occupation. We showed that parental occupation and the participants' own occupation are independently associated with cognition in late life, but do not influence the trajectory of cognitive change. However, when models include childhood mental ability and education the influence of parental and participant occupation is no longer significant. The association in these data between parental occupation and late life cognitive variation is accounted for by childhood mental ability and duration of formal education. However, we cannot exclude the possibility that parental occupation in early life influences early life mental ability and duration of education. The trajectory of change with age is similar across all models, with none of the life course factors (education, parental and participant occupational social class and childhood ability) significantly co-varying with the trajectory of cognitive variation.

A single copy of klotho allele KL-VS is associated with longevity, better health, increased cognition, and bigger regional brain volume. However, its longitudinal effects on cognition and brain volumes, both global and regional, in late life are unclear. In this study we show that, relative to noncarriers, KL-VS heterozygotes had (1) shorter survival; (2) smaller white matter volumes; (3) slower cognitive decline; and (4) greater right frontal lobe volumes. The KL-VS heterozygote survival and white matter volume disadvantages were unexpected. A possible explanation for these results in the context of the literature is a potential interaction between the environment and/or age of the participants, leading to a heterozygote disadvantage. The longitudinal cognitive trajectories indicate that heterozygotes would have an advantage in very late life. Collectively these results suggest that the genotype-survival advantage of the KL-VS allele is age-dependent and possibly mediated through differential cognition and brain volume.

Bone mineral density (BMD) is lower in young amenorrheic athletes (AA) compared to eumenorrheic athletes (EA) and nonathletic controls and may contribute to fracture risk during a critical time of bone accrual. Abnormal bone microarchitecture is an independent determinant of fracture risk and has not been assessed in young athletes and nonathletes.We hypothesized that bone microarchitecture is impaired in AA compared to EA and nonathletes despite weight-bearing exercise.We conducted this cross-sectional study at the Clinical Research Center of Massachusetts General Hospital.We assessed BMD and bone microarchitecture in 50 subjects [16 AA, 18 EA, and 16 nonathletes (15-21 yr old)] using dual-energy x-ray absorptiometry and high-resolution peripheral quantitative computed tomography.Groups did not differ for chronological age, bone age, body mass index, or vitamin D levels. Lumbar BMD Z-scores were lower in AA vs. EA and nonathletes; hip and femoral neck BMD Z-scores were highest in EA. At the weight-bearing tibia, athletes had greater total area, trabecular area, and cortical perimeter than nonathletes, whereas cortical area and thickness trended lower in AA. Trabecular number was lower and trabecular separation higher in AA vs. EA and nonathletes. At the non-weight-bearing radius, trabecular density was lower in AA vs. EA and nonathletes. Later menarchal age was an important determinant of impaired microarchitecture. After controlling for covariates, subject grouping accounted for 18-24% of the variability in tibial trabecular number and separation.In addition to low BMD, AA have impaired bone microarchitecture compared with EA and nonathletes. These are the first data to show abnormal bone microarchitecture in AA.