November 20, 2012
Researchers Identify Gene That Causes Obesity And Lowers Depression
Brett Smith for redOrbit.com — Your Universe Online
Just in time for the appearance of jolly old Saint Nick at the end of the Thanksgiving Day Parade, researchers at McMaster University in Hamilton, Ontario have identified a gene that not only contributes to obesity, but also to a lowered risk of depression.
"The difference of eight per cent is modest and it won't make a big difference in the day-to-day care of patients," said the report´s senior author David Meyre, associate professor in clinical epidemiology and biostatistics at the university. "But, we have discovered a novel molecular basis for depression."
Previous studies have shown a 40 percent genetic component for depression. However, many of these studies have been "surprisingly unsuccessful" at formulating a direct link between genetics and depression, according to co-author Zena Samaan, assistant professor at the university´s Department of Psychiatry and Behavioral Neurosciences.
The Canadian genetics study is also notable because it flips the common perception linking depression and obesity on it head. Popular opinion says obese people become depressed because of their appearance and the resulting social and economic discrimination that ensues. These depressed individuals then exacerbate the cycle by leading less active lifestyles and eating more as a way of mentally coping with their condition.
"We set out to follow a different path, starting from the hypothesis that both depression and obesity deal with brain activity. We hypothesized that obesity genes may be linked to depression," Meyre said.
In the study, the McMaster researchers examined the psychiatric status of patients enrolled in a Population Health Research Institute study based on DSM IV diagnostic criteria. They also analyzed the 17,200 DNA samples from people in 21 countries who participated in the study.
In their analysis, the researchers found the previously identified obesity variant in FTO was associated with an eight percent statistical reduction in the risk of depression. To confirm their findings, the group analyzed the genetic status of patients in three other large international studies.
Meyre said the comprehensive analysis of four different studies supports their conclusion linking FTO to both obesity and depression. He added it is the "first evidence" of the link, which acts independently on both body mass index and depression.
The findings could have ramifications for combating the obesity epidemic that includes 1 in 3 Americans. The problem of obesity has come into focus in the past week with the potential shutdown of the Hostess snack foods brands and the looming Thanksgiving holiday. Many blame snack foods, like Twinkies and Ho-Hos, for contributing to the epidemic because of their cheap, sugary, and ubiquitous appeal.
Despite the potential loss of 18,000 Hostess jobs, many are arguing that stopping the production of these iconic brands is a net win for the U.S. economy. If obesity levels were to lower just slightly, they say, it could reduce healthcare costs paid by the taxpayer.