Childhood BMI has limited effects on mood and behavioral disorders

Child body weight is unlikely to have a big impact on children's mood or behavioural disorders.


Previous studies have linked higher BMI in childhood with mental health. But the nature of the relationship between obesity and these mental health conditions is not clear. But, a new study by the University of Bristol suggests that childhood body mass index is unlikely to significantly impact children’s mood or behavioral disorders.

The results of this study suggest: previous studies might not have fully considered family genetics and environmental factors.

In this study, scientists assessed genetic and mental health data from 41,000 eight-year-old children and their parents from the Norwegian Mother, Father, and Child Cohort Study and Medical Birth Registry of Norway. They carefully examined the association between children’s BMI and symptoms of depression, anxiety, and ADHD. They also considered parental genetics and BMI to differentiate the effects of the children’s genetics from the influence of other factors that affect the whole family.

According to the investigation, a child’s BMI had little impact on anxiety symptoms. Additionally, there was conflicting data regarding the relationship between a child’s BMI and their melancholy or ADHD symptoms. This implies that interventions to reduce childhood obesity are unlikely to affect the incidence of these diseases significantly.

The team found minimal indication that the parents’ BMI impacted the children’s symptoms of ADHD or anxiety when they examined how their BMI affected their mental health. There was a minimal indication of any connection between the child’s mental health and the father’s BMI. Still, the data did imply that having a mother with a higher BMI may be associated with depressive symptoms in children.

Alexandra Havdahl, a Research Professor at the Norwegian Institute of Public Health, said, “Overall, the influence of a parent’s BMI on a child’s mental health seems to be limited. As a result, interventions to reduce parents’ BMIs are unlikely to have widespread benefits to children’s mental health.”

Lead author Dr. Amanda Hughes, Senior Research Associate in Epidemiology at the Bristol Medical School: Population Health Sciences (PHS) at the University of Bristol, said“Our results suggest that interventions designed to reduce child obesity are unlikely to make big improvements in child mental health. On the other hand, policies which target social and environmental factors linked to higher body weights, and which target poor child mental health directly, may be more beneficial.”

Journal Reference:

  1. Amanda Hughes, Eleanor Sanderson, et al. Body mass index and childhood symptoms of depression, anxiety, and attention-deficit hyperactivity disorder: A within-family Mendelian randomization study. eLife. DOI: 10.7554/eLife.74320
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