On 20th October, we lost the Director of our Health Behaviour Research Centre. Professor Jane Wardle, one of the UK’s leading health psychologists, was an extraordinary woman. She had an apparently insatiable appetite for research and new ideas, and the breadth of her expertise was simply awesome. She nurtured us, her PhD students and staff, to develop into independent researchers and supported us when we had personal difficulties. There was always laughter coming out of her office when she was in meetings and Jane’s door was always open to us. We miss her terribly.
While much has been written and said about her achievements and how extraordinary she was by Cancer Research UK, in the Guardian, Lancet, BMJ, The Times, The Psychologist and on Radio 4, we wanted to write about the science behind just a few of her contributions to behavioural science in cancer prevention. Over the next few weeks, our blog will do just that, starting with Jane’s work on understanding the causes of obesity written by Dr Clare Llewellyn and Dr Ali Fildes.
Our understanding of the causes of obesity
Professor Jane Wardle revolutionized our understanding of the genetic basis of human body weight. She was particularly interested in advancing our understanding of the causes of obesity because obesity is an important risk factor for cancer. In fact, obesity is the most important known avoidable cause of cancer after smoking.
We have known for many years that weight has a strong genetic basis. Importantly, Jane established that weight is as heritable now as it was 30 years ago, despite the recent large increases in obesity. This observation has been difficult for researchers to explain given the changes to the food and activity environments that are widely believed to have caused the rising rates of obesity. Researchers were confronted with the question, how can obesity be caused by both genes and the environment at the same time?
In order to answer this question, Professor Wardle developed the ‘Behavioural Susceptibility Theory’. She proposed that genes could be influencing weight through their effects on appetite. The key idea was that individuals who inherit a set of genes that make them more responsive to food cues (want to eat when they see, smell or taste delicious food), and less sensitive to satiety (take longer to feel full) are more susceptible to overeat in the current food environment, and become obese.
In order to test this theory Jane developed a parent-report measure of children’s appetite – the Child Eating Behaviour Questionnaire (CEBQ), and explored the genetic basis of appetite using 10-year-old twins from The Twins Early Development Study (TEDS). Researchers can compare how similar identical twins are, with how similar non-identical twins are, to estimate the importance of genes versus environment for any characteristic, such as appetite. Using the CEBQ she showed for the very first time that food responsiveness and satiety sensitivity both have a strong genetic basis. She also showed that the FTO gene (the first ‘obesity gene’ to be discovered in 2007), and other obesity genes, appear to be influencing weight through impacting satiety sensitivity.
After finding out that appetite is already highly heritable by age 10, Jane realized that she needed to go right back to the beginning of life to explore how genes are influencing appetite and weight from birth. She therefore established Gemini – the largest study of twins ever set up to study genetic and environmental influences on weight from birth. The Gemini study includes over 2400 British families with twins born in 2007, and has now been running for over 8 years. Under Jane’s leadership Gemini has become an internationally recognised study that has advanced our understanding of childhood growth. The success of the study can be measured in its numerous publications on a range of topics from appetite, to food preferences, sleep, physical activity and the home environment. Jane loved the Gemini study, and it shone through in every aspect of her work, from discussions about complex genetic analyses to the design of the annual newsletter sent to the many dedicated families who participate. In total, Gemini has trained (and continues to train) 7 PhD students, 5 postdoctoral researchers, and numerous MSc students. The Gemini team miss Jane terribly but are committed to continuing her incredible legacy.