The findings come from the combined analysis of data from 190,285 individuals from 41 studies worldwide, published this week in Molecular Psychiatry.
Severe childhood maltreatment (physical, sexual or emotional abuse or neglect) affects approximately 1 in 5 children (under 18) in the UK. In addition to the long-term mental health consequences of maltreatment, there is increasing evidence that child maltreatment may affect physical health.
Dr Andrea Danese, child and adolescent psychiatrist from King's College London's Institute of Psychiatry and lead author of the study says: "We found that being maltreated as a child significantly increased the risk of obesity in adult life. Prevention of child maltreatment remains paramount and our findings highlight the serious long-term health effects of these experiences."
Although experimental studies in animal models have previously suggested that early life stress is associated with an increased risk of obesity, evidence from population studies has been inconsistent. This new study comprehensively assessed the evidence from all existing population studies to explore the potential sources of inconsistency.
In their meta-analysis, the authors were able to rule out specific factors which might explain the link – they found that childhood maltreatment was associated with adult obesity independently of the measures or definitions used for maltreatment or obesity, childhood or adult socio-economic status, current smoking, alcohol intake, or physical activity. Additionally, childhood maltreatment was not linked to obesity in children and adolescents, making it unlikely that the link was explained by reverse causality (i.e. children are maltreated because they were obese).
However, the analysis showed that when current depression was taken into account, the link between childhood maltreatment and adult obesity was no longer significant, suggesting that depression might help explain why some maltreated individuals become obese.
Previous studies offer possible biological explanations for this link. Maltreated individuals may eat more because of the effects of early life stress on areas of the developing brain linked to inhibition of feeding, or on hormones regulating appetite. Alternatively, maltreated individuals may burn fewer calories because of the effects of early life stress on the immune system leading to fatigue and reduced activity. The authors add that these hypotheses will need to be directly tested in future studies.
Dr Danese adds: "If the association is causal as suggested by animal studies, childhood maltreatment could be seen as a potentially modifiable risk factor for obesity - a health concern affecting one third of the population and often resistant to interventions.
He concludes: "Additional research is needed to clarify if and how the effects of child maltreatment on obesity could be alleviated through interventions after maltreatment has occurred. Our next step will be to explore the mechanisms behind this link."
Notes to editors:
Paper reference: Danese A & Tan M. 'Childhood maltreatment and obesity: systematic review and meta-analysis' Molecular Psychiatry (in press)
For interviews with the author, or a copy of the paper, please contact: Seil Collins, Press Officer, King's College London, Institute of Psychiatry. Tel: (+44) 7718 697176 or email.
About King's College London:
King's College London is one of the top 30 universities in the world (2012/13 QS international world rankings), and was The Sunday Times 'University of the Year 2010/11', and the fourth oldest in England. A research-led university based in the heart of London, King's has more than 25,000 students (of whom more than 10,000 are graduate students) from nearly 140 countries, and more than 6,500 employees. King's is in the second phase of a £1 billion redevelopment programme which is transforming its estate.
King's has an outstanding reputation for providing world-class teaching and cutting-edge research. In the 2008 Research Assessment Exercise for British universities, 23 departments were ranked in the top quartile of British universities; over half of our academic staff work in departments that are in the top 10 per cent in the UK in their field and can thus be classed as world leading. The College is in the top seven UK universities for research earnings and has an overall annual income of nearly £525 million (year ending 31 July 2011).
King's has a particularly distinguished reputation in the humanities, law, the sciences (including a wide range of health areas such as psychiatry, medicine, nursing and dentistry) and social sciences including international affairs. It has played a major role in many of the advances that have shaped modern life, such as the discovery of the structure of DNA and research that led to the development of radio, television, mobile phones and radar.
King's College London and Guy's and St Thomas', King's College Hospital and South London and Maudsley NHS Foundation Trusts are part of King's Health Partners. King's Health Partners Academic Health Sciences Centre (AHSC) is a pioneering global collaboration between one of the world's leading research-led universities and three of London's most successful NHS Foundation Trusts, including leading teaching hospitals and comprehensive mental health services. For more information, visit: http://www.kingshealthpartners.org.
The College is in the midst of a five-year, £500 million fundraising campaign – World questions|King's answers – created to address some of the most pressing challenges facing humanity as quickly as feasible. The campaign's five priority areas are neuroscience and mental health, leadership and society, cancer, global power and children's health. More information about the campaign is available at http://www.kcl.ac.uk/kingsanswers.
Seil Collins | EurekAlert!
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