Source: http://www.telegraph.co.uk/health/healt ... iness.html
Fat people may be more jolly because a gene which contributes to obesity also lowers the risk of depression, researchers claim.
Photo: ALAMY
By Nick Collins, Science Correspondent
3:57PM GMT 20 Nov 2012
People with particular variants of a gene known as FTO, the largest genetic factor behind obesity, are eight per cent less likely to suffer from depression, a new study found.
The findings, which are the first to link the gene with protection against depression, could help explain why some people are happier than others.
They question the common assumption that obesity and depression are mutually reinforcing – that obese people are more prone to become depressed because of their appearance, and depressed people are more likely to gain weight because of a less active lifestyle and unhealthy eating habits.
Dr David Meyre, senior author of the study, said: "The difference of eight per cent is modest and it won't make a big difference in the day-to-day care of patients, but we have discovered a novel molecular basis for depression."
Previous research on twins and other siblings have suggested that depression may be up to 40 per cent hereditary, but no studies have been able to firmly link particular genes to the condition.
In the new study, the scientists examined data on 17,200 DNA samples donated by volunteers from 21 different countries as part of a wider project by the Population Health Research Institute.
They found that the variant in the FTO gene, which has already been shown to raise the risk of obesity, was also linked to a lower depression risk. The same link was later identified in three other large international studies.
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