Genetic link between obesity and depression discovered, scientists say | Obesity



According to researchers, being overweight can cause depression, the effects of which are largely psychological.

While previous studies have shown that obese people are more likely to suffer from depression, it is not clear whether this is due to depression leading to weight changes or the other way around.

Now, in the largest study of its kind, experts claim that having genetic variants linked to a high body mass index (BMI) can lead to depression, with a stronger effect in women than in women. men. Plus, they say research suggests the effect could be due to factors like body image.

“People who are more overweight in a population are more depressed, and that’s probably at least in part [a] causal effect of BMI [on] depression, ”said study co-author Professor Tim Frayling of the University of Exeter School of Medicine.

Write in the International Journal of Epidemiology, researchers from the UK and Australia describe how they used data from UK Biobank, a research company involving 500,000 participants aged 37 to 73 who were recruited in 2006-2010.

Researchers looked at 73 genetic variants linked to high BMI that are also associated with a higher risk of diseases such as diabetes and heart disease. They also looked at 14 genetic variants that were linked to a high percentage of body fat but were associated with a lower risk of such health problems. While the former group might be linked to depression by biological or psychological mechanisms, the latter is only expected to have a psychological effect.

The team then looked at participants’ hospital data and responses to a multitude of questionnaires, including self-reports from seeing a GP or psychiatrist for anxiety or depression. The team identified around 49,000 participants who they believed were suffering from depression.

Overall, the team found that people with a higher BMI were more likely to be depressed.

The researchers also found that being genetically predisposed to a higher BMI was linked to depression, with the effect being stronger in women than in men. The results were maintained even when they performed additional tests, such as excluding people with a family history of depression, and when the analysis was repeated on data from a large international project called the Psychiatric Genomics Consortium. .

Focusing on the 73 genetic variants and taking into account factors such as age and gender, they found that for every 4.7 point increase in BMI, the odds of being depressed increased by 18%. overall and 23% for women.

When the team pooled data from different sources, they found that the 14 genetic variants that increase body fat but are not linked to poor metabolic health were also linked to an increased risk of depression.

“This suggests that the psychological component is just as strong as any physiological component, though [the latter] is there at all, ”Frayling said, suggesting that poor body image could be a mechanism at play.

The study has some limitations: it focused primarily on people of white European descent and involved some self-reported data.

While the study didn’t show that gaining weight for other reasons would increase the risk of depression, Frayling said it was likely. “It allows [one] deduce that greater effects on BMI would have greater effects on depression, ”he said.

Naveed Sattar, professor of metabolic medicine at the University of Glasgow, praised the research. “These new findings are perhaps the strongest yet to suggest that higher weights may actually contribute to depression,” he said. “Of course, there are many other factors that can cause depression, but even so, losing weight can be helpful in improving the mental health of some people, while staying lean in general should help reduce the risk of depression. “


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