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Fat And Happy

Genetic Challenge to the Common Perception of A Link Between Depression and Obesity

Ever wondered why some of your friends are happier than others? Ever wondered whether there might be a genetic basis for their happiness? Got any fat friends? Do they seem happier than your thin friends?

These and similar questions occurred to researchers at McMaster University in Canada. They’ve discovered genetic evidence relating to why some people are happier than others, and they found it in an unusual place; the fat mass and obesity-associated protein also known as alpha-ketoglutarate-dependent dioxygenase, or the FTO gene

This gene, which substantially controls and contributes to obesity, has the serendipitous effect of also contributing to an eight percent reduction in the risk of serious depression. So this “fat” gene is also a “happy” gene.

The research appears in a study recently published in the journal Molecular Psychiatry. The paper was produced by senior author David Meyre, associate professor in clinical epidemiology and biostatistics at the Michael G. DeGroote School of Medicine and a Canada Research Chair in genetic epidemiology; first author Dr. Zena Samaan, assistant professor, Department of Psychiatry and Behavioural Neurosciences, and members of the Population Health Research Institute of McMaster University and Hamilton Health Sciences.

“The difference of eight per cent is modest and it won’t make a big difference in the day-to-day care of patients,” Meyre said. “But, we have discovered a novel molecular basis for depression.”

Previous studies have shown a statistical correlation suggesting a forty percent genetic component to depression but so far there has been little success in actually identifying the genes involved. Researchers have been “surprisingly unsuccessful” in this search and produced no convincing evidence so far, Samaan said.

The McMaster discovery challenges the common perception of a reciprocal link between depression and obesity: That obese people become depressed because of their appearance and social and economic discrimination; depressed individuals may lead less active lifestyles and change eating habits to cope with depression that causes them to become obese.

“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.

The McMaster researchers investigated the genetic and psychiatric status of patients enrolled in the EpiDREAM study led by the Population Health Research Institute, which analysed 17,200 DNA samples from participants in 21 countries.

In these patients, they found the previously identified obesity predisposing genetic variant in FTO was associated with an eight per cent reduction in the risk of depression. They confirmed this finding by analysing the genetic status of patients in three additional large international studies.

Meyre said the fact the obesity gene’s same protective trend on depression was found in four different studies supports their conclusion. It is the “first evidence” that an FTO obesity gene is associated with protection against major depression, independent of its effect on body mass index, he said.

Now a word of caution from your correspondent; this discovery and its implications do not, I repeat DO NOT mean that if you’re unhappy it makes sense to get on the blower and order up ten family buckets of KFC. That will just make you fat.

Happy is a different state of mind altogether.

For help with depression contact “Beyondblue”:

 http://www.beyondblue.org.au/index.aspx?

Story Source: The above story is edited from materials provided by McMaster University

Journal Reference:

1. Z Samaan, S Anand, X Zhang, D Desai, M Rivera, G Pare, L Thabane, C Xie, H Gerstein, J C Engert, I Craig, S Cohen-Woods, V Mohan, R Diaz, X Wang, L Liu, T Corre, M Preisig, Z Kutalik, S Bergmann, P Vollenweider, G Waeber, S Yusuf, D Meyre. The protective effect of the obesity-associated rs9939609 A variant in fat mass- and obesity-associated gene on depression. Molecular Psychiatry, 2012; DOI: 10.1038/mp.2012.160

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here are opinion only.

Keywords: McMaster University, D Meyre, Z Samaan, FTO gene, obesity and depression, happy gene