ESPE Abstracts

Background: In later life, osteoporosis and poor cognitive function often co-exist. This has commonly been attributed to post-menopausal estrogen loss, but there is increasing recognition of cross-talk between the brain and bone. For example, in animal models, bone derived osteocalcin has positive associations with brain volume and cognitive function whilst brain-derived neurotransmitters appear to influence bone mass. Despite this, a common early life origin for osteoporosis and poor cognitive function has not been explored. We assessed the relationships between intelligence, working memory and bone mineralization in childhood.

Methods: The Southampton Women’s Survey is a prospective mother-offspring birth cohort study (Southampton, UK). The children were assessed at age 6-7 years, including occipitofrontal circumference (OFC, proxy for brain volume), intelligence quotient (IQ) [Wechsler Abbreviated Scale of Intelligence] and visual-spatial working memory [CANTAB® Delayed Matching to Sample (DMS)]. Whole-body-less-head (WBLH) and lumbar spine dual-energy X-ray absorptiometry (DXA) were performed using a Hologic Discovery instrument yielding bone area (BA), bone mineral content (BMC) and bone mineral density (BMD). All variables were adjusted for age and sex and associations assessed using linear regression for standardized variables (β represents standard deviation (SD) difference per SD of cognitive function or OFC).

Results: 1331 children (mean age 6.8 years (SD 0.33 years), 51.5% male) attended for DXA. OFC, IQ and DMS was assessed in 1250, 551 and 490 of these children, respectively. OFC (β=0.25 SD/SD, 95%CI 0.20, 0.30), IQ (β=0.11 SD/SD, 95%CI 0.02, 0.19), and DMS (β=0.11, SD/SD, 95%CI 0.01, 0.20) were all positively associated with WBLH BA. Associations between OFC, IQ and DMS and lumbar spine BA were similar. Positive associations were observed between OFC, IQ and DMS and WBLH BMC, but only OFC was associated with BMD (WBLH: β=0.38 SD/SD, 95%CI 0.33, 0.43; LS: β=0.19 SD/SD, 95%CI 0.13, 0.24). Associations were similar when stratified by sex.

Conclusion: Childhood OFC was positively associated with bone size and mineralization, whereas IQ and visual-spatial working memory were associated only with skeletal size, although this relationship was assessed in a smaller cohort of children. These findings suggest that a common early life determinant for cognitive function and skeletal growth should be explored.