Kids of the 90s: Tracking a decade of children's health 14/8/01. By Giles Newton ALSPAC, a huge study of children's health in the west of England, is providing a wealth of valuable information.

Inspired by the Jesuit maxim 'Give me the child until he is seven, and I will show you the man,' the director Michael Apted began his lifelong documentary series 7 Up in 1964. Apted profiled 14 representative seven-year-olds from a wide range of class backgrounds, and has since revisited his subjects to update his sketches every seven years - catching up with them most recently with 42 Up in 1999.

A group of children in the south-west of England have also been documented for the last ten years, although this study is not examining class differences so much as the wider issue of child health and development. And instead of following 14 children once every seven years, the project began with 14 000 children and each child has been checked regularly ever since.

This massive endeavour - the Avon Longitudinal Study of Parents and Children (ALSPAC; also known as 'Children of the 90s') - celebrated its tenth birthday in June 2001 with a meeting at the Royal Society in London. The meeting became a double celebration with the announcement of a new injection of funds from the Wellcome Trust, the Medical Research Council and the University of Bristol to underpin the next five years of research.

Since 1991, ALSPAC has been following the health of thousands of children in the Avon region of the UK.

A family matter

"We're looking at the 'big synthesis' of understanding disease: genetic variation, life course, environmental exposures and transgenerational effects," says Professor Marcus Pembrey, the Chairman of the ALSPAC Genetics Advisory Committee. "In most common diseases, genetic influences are likely to be conditional on the environment."

Finding and checking such associations between genetic and environmental factors, and teasing apart the pathways that lead over time to common disorders, requires detailed data from an enormous number of people, so ALSPAC began - back in 1991 - with the enrolment of 14 000 mothers-to-be. The mothers came from all over the Avon region, which includes the city of Bristol and rural areas, and have a good mix of social backgrounds and housing, with little outward migration.

"It is a microcosm of what is going on elsewhere in England and Wales," says Professor Jean Golding, the Scientific and Executive Director of ALSPAC who has led the project since its inception.

Maintaining the enthusiasm and interest of the families and in particular the children, over ten years has been both crucial and highly successful - more than 12 000 families are currently involved in the study. The oldest of the children are now ten, the youngest eight, and they attend more than 1500 schools, not only around Bristol, but throughout the UK, and in 31 countries across the globe.

'A huge biological enterprise'

At the beginning of the project, pregnant mothers and their partners were asked detailed questions about themselves, their lifestyle and their health; after delivery, they were asked an array of questions about their newborns. Questionnaires have remained the cornerstone of the study, but these have been supplemented with regular physical assessments, health records, and biological samples from mothers and children, environmental readings and interviews with children. "The emphasis is on the child," says Professor Golding, "but we have also recorded data on parents' and grandparents' health."

The amount of data accrued by ALSPAC is staggering. The ALSPAC post room sends out six sacks of mail per day, and 1200 questionnaires and 650 reminder letters per week. Over the last ten years ALSPAC has sent out 650 000 questionnaires. Meanwhile, ALSPAC has been collecting blood samples for its DNA bank - so far, it holds more than 9000 DNA samples from mothers, 6500 from children, with a further 2500 being extracted from stored cord blood samples. Milk teeth have been saved to study links between illness and pollutants. "We've been the local tooth fairy, collecting up to four teeth per child," says Professor Golding. "Altogether, it's a huge biological enterprise."

Over the last few years, the project has kicked into an ever higher gear with detailed examinations of all of the children. This concept was trialled with the 'Children in Focus', a 10 per cent sample of the children who were examined at four, eight and 12 months, and then at six-monthly intervals to the age of five. The examinations included measures of growth, cognitive ability, speech and language development, allergies, hearing and vision. From the age of seven, all the children were invited to take part in these detailed tests. At eight years old, the children have psychological and psychometric testing, and at nine they have physical measurements, including a whole-body X-ray (at a low dose). "The children are very excited about these X-rays," says Professor Golding, "as they can take away a picture of their whole skeleton to show to their friends at school."

The detailed observations and biological samples provide an invaluable resource for researchers trying to understand child health and development. The list of topics being investigated reads like a medical dictionary, as it includes allergies, anxieties and phobias, asthma, autism, cerebral palsy, deafness, depression, dyslexia, eczema, epilepsy, hyperactivity, obesity, and vision. Many key findings have emerged from these projects, and more than 100 publications have resulted from the ALSPAC study over the last ten years.

These research projects are funded by many different agencies in the UK and the USA (the Wellcome Trust's current funding for ALSPAC-related research projects is valued at more than £2 million), and have helped keep ALSPAC running – "although it's been a hand-to-mouth existence at times," admits Professor Golding. The new grant announced in June will provide core funding to alleviate this dependency on project funds: Wellcome and the MRC are injecting core funding of more than £6 million, and the University of Bristol £5 million. The Trust is also providing an additional £2 million to establish a collection of cell lines from children and their parents, which will allow DNA samples to be used as a long-term resource for future studies.

Longitudinal studies such as ALSPAC provide essential data for researchers trying to find lifestyle changes or drugs that can prevent or treat disease, but the studies can only be successful with the support and enthusiasm of the volunteers who provide the information. "It is a testament to the ALSPAC team that so many families are still in the study today," says Professor Roland Levinsky, Chairman of the ALSPAC Scientific Steering Committee. "It is in the next ten to 20 years that the full value of the study will be realised."

Key findings from ALSPAC studies

• Parents who smoke, even passively, are likely to take longer to conceive a child.
• A vegetarian diet during pregnancy may not be good for the developing fetus.
• Eating oily fish and breast feeding improves a child's eyesight.
• Girls have more tomboy tendencies if their mothers had high testosterone levels while pregnant.
• Putting babies to sleep on their backs reduces the risk of cot death.
• Weaning babies onto lumpy foods while less than nine months old leads to fewer eating problems later in life.
• Children brought up in very hygienic homes are more likely to develop asthma.
• Nut and peanut allergies are much more common than previously thought, and in 90 per cent of cases are preceded by eczema, suggesting that peanut oil-containing skin creams may be responsible.
• Some chemicals used in homes (such as air fresheners and other aerosols) appear to cause headaches.