September 27, 2024, 12:05 pm | Read time: 5 minutes
Previous studies have already shown that severely overweight children have a higher risk of metabolic and cardiovascular diseases as well as depression in adulthood. A new study now shows that children with a high BMI may also have an increased risk of schizophrenia.
Childhood obesity is a serious problem. According to the Federal Ministry of Health, 9.5 percent of children and adolescents aged three to 17 in Germany are overweight, and 5.9 percent are obese.1 A person is considered overweight with a Body Mass Index (BMI) of 25, and obese with a BMI of 30.2 Overweight often continues into adulthood and can later lead to cardiovascular diseases, diabetes, joint problems, or even depression, as warned by the Federal Ministry of Health. Chinese researchers have now found that children with a high BMI may also have a higher risk of developing schizophrenia in adulthood.
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Overview
Children with high overweight have a higher risk for various diseases
Childhood obesity is a major and widespread problem worldwide. Studies have shown that high overweight in adolescence is a marker for increased cardiometabolic risk in both adolescents and adults.3 This means that children and adolescents with severe overweight have a higher risk of developing cardiovascular diseases and metabolic disorders such as diabetes mellitus later in life. Additionally, obesity is likely to persist from childhood into adulthood. But that’s not all: Chinese researchers found in a recent study that children with a high BMI later have a higher risk of mental illnesses such as schizophrenia as adults.4
How the study was conducted
In their study, published in the journal Science Advances, the researchers examined the health data of individuals who participated in two large genetic studies. They wanted to find out if childhood overweight is linked to the risk of mental illnesses.
To do this, they analyzed data from the “Psychiatric Genomics Consortium,” a long-term project researching the genetic foundations of psychiatric disorders. They also used data from the FinnGen project, which collected biological samples from 500,000 participants in Finland to improve health through genetic research. In their data analysis, the researchers looked for evidence of whether people who were obese as children developed mental health issues in adulthood. The focus was on the following mental illnesses:
- Obsessive-compulsive disorders
- Major depression
- Anxiety disorders
- Alzheimer’s
- Schizophrenia
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Connection between child BMI and schizophrenia
The data analysis revealed that there was no connection between childhood obesity and the mental illnesses described above–except for schizophrenia. Here, however, the connection was clearly evident, as the researchers explained in their study evaluation. They also noted that this connection exists independently of obesity later in life or other lifestyle factors. This means that even if one loses weight as an adult, the risk of schizophrenia remains elevated if one was obese as a child.
Why severe overweight in childhood can later lead to schizophrenia is something the researchers cannot currently explain. One hypothesis is that excess fat tissue could negatively affect the brain during a critical developmental phase. Another possible explanation is that obesity could negatively impact the gut microbiome, which in turn can lead to mental illnesses–research offers some clues for this.
However, overweight in children also leads to psychological stress caused by interpersonal stress factors such as social stigmatization, bullying, and exclusion. As a result, children may be more susceptible to mental illnesses later in life, according to another explanation by the researchers.
But even without a clear explanation for the findings, the study shows–according to the scientists–how important it is to prevent or treat obesity in children. Health institutions should intensify their efforts to protect children from overweight, they urgently recommend.
Body Mass Index under criticism
Although the Body Mass Index is often used to check whether someone is overweight, it is criticized. The BMI is calculated by dividing one’s body weight by “height times height in meters.” For example, a calculation for a man who is 1.85 meters tall and weighs 90 kilograms:
- 90 divided by “1.85 x 1.85” results in a BMI of 26.3.
The problem is that a man, for example, with a weight of 90 kilograms and a BMI of 26 is already considered overweight according to the BMI. However, the BMI cannot distinguish between a muscular, fit man and an equally heavy unfit man with a high body fat percentage. Therefore, health expert Dr. Michael Despeghel concluded in a previous FITBOOK article: “The BMI says nothing about a person’s health or disease risk.”
A more meaningful alternative to the BMI as an index for overweight or underweight could be the waist-to-hip ratio and the waist-to-height ratio. How it works is explained by FITBOOK in the article “Why the waist-to-hip ratio might be more meaningful than the BMI”.