The relationship between obesity (BMI >30) and depression has been characterized as the chicken/egg dilemma. Which came first? It seems self evident that depression might lead one to seek out the solace and sensory rewards of foods. And viewing that seemingly self-evident proposal in the mirror; obesity might lead to social isolation, discrimination and other real or perceived losses all associated with social stigmata, which might lead inevitably to a depressive state. The question that might be posed is: Do those with obesity have mood disorders (specifically depression) more often than those without obesity?
Research in the past has shown that obesity is significantly associated with depression and other mood disorders. What the research hasn’t been able to show is a cause and effect relationship between obesity and depression. There are a small number of studies examining the possibility of depression leading to obesity[1]. And an equally small number of studies showing that obesity might lead to depression[2]. The research in general doesn’t really lend a direction to this dilemma.
A recent study published in the Archives of General Psychiatry sought to better define the population of obese individuals at risk for depression. Or if you look at it from the other perspective, depressed individuals that happen to be obese. The study looked at a cross section of America[3] and simply examined the association between obesity and mood disorders.
They found in their cross-section of America that from 2001 to 2003 in a random sampling of the 48 contiguous states, that 25.5% of us have a BMI greater than or equal to 30. That is, 25.5 % of us are obese or larger. Further, 18.6% of those with a BMI > 30 had a major depressive disorder at one time in their lifetime. I’ll sum up the other findings:
1. White (non-hispanics) were more often depressed if obese than non-whites
2. Depression was more common in those obese individuals with higher levels of educational attainment
3. As age increased, obesity was more often associated with depression
Cross-sectional analysis such as the study above might be more a snapshot of America than an analysis of trends, but the snapshot shows some interesting associations. In higher socioeconomic circles there might be more pressure to be normal weight and those with obesity are shunned to a greater extent than those in lower socioeconomic circles. Cultural and ethnic analyses show that in some racial groupings, depression is low and may be low due to greater acceptance of obesity by peers. And those attaining higher levels of education may feel guilt and loss of self-control (with subsequent depressive episodes) due to a contrast between the self-control and will power it takes to attain higher levels of education and the state of obesity.
Which begets which? I think after examining a sampling of the studies it appears to work both ways. In some cases, possibly those in higher social strata with higher levels of education, obesity might lead to social isolation and depression. However in some (not so clearly identified by the above research study), depression and isolation may lead to overeating and sensory rewards which can lead to obesity. I think the forces leading one disorder to the other are situation specific and not amenable to generalized identifying markers or settings.
WG
[1] Goodman, et al. A Prospective Study of the Role of Depression in the Development and Persistence of Adolescent Obesity. Pediatrics 2002; 110, 497-504
[2] Roberts EE, et al. Prospective Association between Obesity and Depression. Int J Obesity Rel Met Disorders 2003;27: 514-26
[3] Simon et al. Association Between Obesity and Psychiatric Disorders in the US Adult Population. Archives of General Psychiatry. 2006;63:824-30
3 comments:
WG: another interesting post. A physical activity sciences expert, who works on mental health aspects of obesity, and whom I interviewed for my PhD, put it this way: stress seems to make people eat, while anxiety seems to suppress appetite. What do you think based on your experience?
You may also like to see this news article which suggests that changing to a low-fat diet can induce stress:
http://www.sciencedaily.com/releases/2007/04/070418091945.htm
Sorry the URL seems to have broken:
http://www.sciencedaily.com/releases/
2007/04/070418091945.htm
Shefaly: I want to appologize for my late response to your entry. I've been on the road again and have let my blog lapse. But as a student of physiology, I find it hard to separate stress from anxiety. Anxiety creates stress and stress creates anxiety. The stress response certainly inhibits autonomic functions that allow digestion. In short, if you see a mastadon charging, are you thinking of what the kids might want for dinner? Or are you tachycardic, spiked with catecholamines and ready to bolt up a tree? Depression on the other hand is a slow pervasive feeling of helplessness. And how that impacts food intake behavior appears to be highly indvidualized, depending upon circumstances. Death of a loved one will almost always lead to lower rates of food intake and feelings of inadequacy might fall either way. Anyway thanks for the URL and for visiting.
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