More than half of 23-year-olds in a European study show restrictive, emotional or uncontrolled eating behaviours, according to new research led by the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King's College London. Structural brain differences appear to play a role in the development of these eating habits.
The study, published in Nature Mental Health, investigates the links between genetics, brain structure and disordered eating behaviours in young people. Researchers found that the process of 'brain maturation', whereby the volume and thickness of the cortex (the outer layer of the brain) decreases during adolescence, is a factor in whether teenagers develop restrictive or emotional/uncontrolled eating behaviours in young adulthood.
Restrictive eating behaviors, such as dieting and purging, involve the deliberate limitation of food intake to control body weight and shape. In contrast, emotional or uncontrolled eating behaviors, like binge-eating, are characterised by episodes of consuming food in response to negative emotions or compulsive urges.
The researchers analysed data from 996 adolescents in the IMAGEN longitudinal cohort in England, Ireland, France and Germany. Participants provided genetic data, completed questionnaires about their wellbeing and eating behaviours, and had an MRI scan at ages 14 and 23. At age 23, participants were categorised into three types of eating behaviours: healthy eaters (42 per cent), restrictive eaters (33 per cent) and emotional or uncontrolled eaters (25 per cent).
The study found that the three groups had different patterns of mental health and behaviour over time.
Young people with unhealthy eating behaviours (restrictive and emotional/uncontrolled) at age 23 had higher levels of both internalising problems (for example, anxiety or depression) and externalising problems (for example, hyperactivity, inattention or conduct problems) at age 14, compared to healthy eaters. Internalising problems significantly increased with age between 14 to 23 among unhealthy eaters. Although externalising problems decreased with age in all groups, overall levels were higher among those with emotional or uncontrolled eating.
Restrictive eaters dieted more throughout adolescence compared to healthy eaters. Emotional/uncontrolled eaters increased their dieting between ages 14 to 16 and binge eating between ages 14 to 19, compared to healthy eaters. Unhealthy eating behaviours were linked with obesity and increased genetic risk for high BMI.
Researchers analysed Magnetic Resonance Imaging (MRI) data at 14 and 23 years to investigate brain maturation over time and how much the volume and thickness of the cortex had decreased. Results indicated that brain maturation was delayed and less pronounced in unhealthy eaters. It played a role in the link between mental health problems at age 14 and development of unhealthy eating behaviours at age 23 and this connection was unrelated to BMI. Reduced brain maturation also helped explain how genetic risk for high BMI influences unhealthy eating behaviours at age 23.
In particular, reduced maturation of the cerebellum – a brain region that controls appetite – helped explain the link between genetic risk for high BMI and restrictive eating behaviours at age 23.
The research, which received funding from the Medical Research Foundation, Medical Research Council and National Institute for Health and Care Research (NIHR) Maudsley Biomedical Research Centre, highlights how brain maturation, genetics and mental health difficulties interact to contribute to eating disorder symptoms.
Xinyang Yu, PhD student at King's IoPPN and first author of the study, said: "Our findings reveal how delayed brain maturation during adolescence links genetics, mental health challenges and disordered eating behaviors in young adulthood, emphasising the critical role of brain development in shaping eating habits."
Dr Zuo Zhang, Research Fellow at King's IoPPN and co-author of the study, said: "By showing that different unhealthy eating behaviours are linked to differential trajectories of mental health symptoms and brain development, our findings may inform the design of more personalised interventions."
Professor Sylvane Desrivières, Professor of Biological Psychiatry at King's IoPPN and senior author of the study, said: "Our findings highlight the potential benefits of improved education aimed at addressing unhealthy dietary habits and maladaptive coping strategies. This could play a crucial role in preventing eating disorders and supporting overall brain health."
