Obesity is associated with a significant increase in risk for mood and anxiety disorders but significantly lower risk for substance abuse
Obesity is associated with a 25 percent increase in risk
for mood and anxiety disorders and a 25 percent decrease in risk for substance
abuse, according to an article in the July issue of Archives of General Psychiatry.
About 31 percent of all U.S. adults were obese in 2000,
an increase from 23 percent in 1990, according to background information in the
article. Previous studies have suggested a link between obesity and depression,
but little research has examined the associations between obesity and other psychiatric
disorders.
In the current study, Gregory E. Simon, MD, MPH, and
his American colleagues studied 9,125 adults nationwide who were interviewed as
part of a large national survey of mental disorders between February 2001 and
February 2003. Participants (average age 44.8 years) completed an in-home interview
that included questions about demographic characteristics, height, weight and
psychiatric disorders.
Psychiatric conditions included mood disorders such as
major depression, dysthymia, and bipolar disorder; anxiety disorders such as panic
disorder and generalized anxiety disorder; and substance abuse disorders, including
alcohol or drug dependence.
Among all participants, 6,795 had a body mass index of
less than 30 and 2,330 had an index of 30 or greater and were therefore considered
obese. Adults who were obese had a higher prevalence of mood and anxiety disorders
and a lower prevalence of substance abuse disorders over their lifetimes.
These associations were similar for men and women. The
link between obesity and mood disorders appeared strongest in non-Hispanic whites
and in people with higher education levels.
“The estimated prevalence of lifetime mood disorder in
those with body mass indexes below 30 and in those with indexes 30 or higher translates
to a population-attributable risk of 24 percent, which indicates that nearly one-quarter
of the cases of obesity in the general population are attributable to the association
with mood disorder,” the authors wrote. “This calculation illustrates the public
health importance of the association but does not indicate a direction for the
causal relationship. It is equally correct to state that more than one-fifth of
cases of mood disorder in the general population are attributable to the association
with obesity.”
Increased appetite, weight gain, reduced physical activity
and binge eating have all been associated with depression, potentially increasing
risk for obesity. However, obesity could also contribute to depression by limiting
physical activity, or through the stigma that may be associated with being overweight,
especially among some women and particular sociodemographic groups. An unknown
third cause also could be linked to both. The results also do not indicate the
mechanisms behind the negative association between obesity and substance abuse.
“We conclude that obesity is meaningfully associated
with a range of common mood and anxiety disorders in the general U.S. population,”
the authors wrote. “Obesity is associated with a moderately lower risk of substance
use disorder. Variation in the obesity-depression relationship by education level
and race/ethnicity suggests an important role of social or cultural factors in
mediating or moderating the relationship between obesity and mood disorders.”
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