thLongitudinal modelling of adiposity, its determinants and its health consequences across childhood and adolescence

Child obesity has become far more common in recent years, and is associated with health problems. This project looks at how obesity develops and changes over childhood and adolescence, how this is affected by changes in diet and physical activity, and how it relates to changes in blood pressure and other measures of health that are indicators of future heart disease risk. The project will also look at whether changes in early life can predict whether an individual is likely to be extremely obese when they are a young adult. Some obese people remain healthy despite being obese (e.g. they do not have higher risk of heart disease). This project will also look at whether changes in early life can predict which obese people will stay healthy.

This project uses information from a study called ALSPAC, or ‘Children of the 90s‘. This started with over 14,000 pregnant women in Bristol in 1991/92. The mothers and their children have been followed ever since. I will also use information from ‘Born in Bradford‘ which is following 10,000 mothers and their children (5000 of European origin and 5000 of Pakistani origin) who were recruited when the mothers were pregnant between 2007-10.

Aim
To determine how adiposity changes from birth to adolescence and risk factors for, and consequences of, different patterns of adiposity change.

Objectives
1. To characterise patterns of change in adiposity (BMI 0-18 years, waist-circumference 7-18 years, and DXA-determined fat mass 9-18 years) and its associated cardiovascular risk factors (blood pressure 7-18 years, lipids, insulin and inflammatory markers 9-18 years) across childhood and adolescence
2. To identify genetic, lifestyle (longitudinal patterns of diet and physical activity), socioeconomic (including differential socioeconomic position between family generations) and ethnic determinants of adiposity changes across childhood and adolescence
3. To identify how adiposity changes relate to changes in cardiovascular risk factors in childhood and adolescence, and whether there is a time lag between adiposity changes and changes in cardiovascular risk factors
4. To identify characteristics associated with 1) extreme obesity in adolescence (ages 15-18) and 2) metabolic resilience to obesity

Methodology
The Avon Longitudinal Study of Parents and Children is a prospective cohort study; >14,000 pregnant women were recruited between 1991-1992. Follow-up continues, and has involved clinics, links to routine data, and questionnaires to the mother, her partner, and the child. Adiposity measures include repeat measures of BMI, waist circumference, and DXA-determined fat mass. Cardiovascular risk factors include repeat measures of blood pressure, lipids, insulin and inflammatory markers. Diet data are available from food frequency questionnaires and diet-diaries. Physical activity and sedentary behaviours data were collected using accelerometers and questionnaires. Family socioeconomic factors are available from questionnaires and participants‘ own educational attainment from links to routine data. Additional analyses will be conducted on the Born in Bradford cohort; 5000 European- and 5000 Pakistani-origin families will have been recruited by December 2010. Detailed lifestyle, socioeconomic and obstetric data are collected; growth from birth to 5-years will be available from health visitor assessments and research clinic measurements. Relevant statistical methods - multivariable regression, structural equation modelling, multilevel/multivariate models, Bayesian analysis, etc - will be used as appropriate.

Scientific/medical opportunities
To design obesity prevention/treatment interventions, improved understanding of life-course influences on obesity is essential. The proposed research addresses this by characterising patterns of adiposity change from birth to adolescence in the most detailed dataset currently available. Hence it will potentially identify sensitive periods for developing adverse levels and patterns of adiposity, risk factors for adverse adiposity changes, how different patterns relate to cardiovascular risk, and which factors are associated with both extreme obesity and metabolic resilience to obesity.