The study, conducted by Deborah Gibson-Smith and colleagues from VU University in the Netherlands, also found that carrying excess weight over a lifetime quadrupled an individual’s likelihood of developing depression, compared to only being overweight as an adult.
More than one in three children in the United States are overweight, while one in five between the ages of 2 and 19 are obese, according to the U.S. Centers for Disease Control and Prevention. This trend is similar to that of England, where one in three children ages 10 to 11 are now overweight or obese, according to the National Child Measurement Programme.
“Our findings suggest that some of the underlying mechanisms linking overweight or obesity to depression stem from childhood,” the authors write. “A shared genetic risk or low self-esteem, which is frequently associated with those who do not conform to the ideal body type, could be responsible.”
While previous studies have linked obesity to a higher likelihood of becoming depressed, few have examined the influence of early-life obesity over an extended period of time, or the age-related effect of obesity on depression risk.
In the new study, the team analyzed the connection between being overweight during childhood and lifetime depression in nearly 889 participants from the population-based Age, Gene/Environment Susceptibility (AGES) study conducted from 2002 to 2006. The scientists reviewed subjects of a longitudinal study of people born between 1907 and 1935 who lived in Reykjavik, Iceland, in 1967.
Between 2002 and 2006, the team invited a random group of surviving participants from the first study to join the AGES study. The study subjects, whose average age was 75 years, were tested to see whether they had current depressive symptoms or had ever experienced a major depressive disorder in the past.
The participants were evaluated on their body mass index (BMI), which measures body fat based on a person’s height and weight. A BMI of between 25 and 29.9 is considered overweight. The team diagnosed 39 participants as having major depression at some point in their lives.
The data was adjusted for sex and the age at which the subjects’ BMI measurements were recorded. Though not a perfect method for determining whether a person is overweight, BMI can provide a general sense of a person’s body fat.
This is an observational study, so no conclusions can be drawn about cause and effect. However, the findings back up earlier studies that noted an increased risk of depression among young obese people.
“Given the rise in adolescents’ obesity and greater influence of social media on body image, understanding the association between childhood obesity and depression is critical,” the authors write.