As obesity becomes a problem generating increasing levels of concern in
various countries, the psychological ramifications of the condition are also
receiving more attention.
For example, Stefan Kloiber, M.D., a psychiatry resident at the Max Planck
Institute of Psychiatry in Munich, Germany, and colleagues studied 408
inpatients with a DSM-IV-diagnosed major depression over a five-week
period. They found that these patients had a significantly greater body mass
index (BMI) than healthy control subjects. They also found that of the
depressed patients in their cohort, those who were overweight (with a BMI of
25 or greater) showed a significantly slower response to antidepressant
treatment than did those of normal weight (with a BMI between 19 and 24).
"Our findings suggest that overweight and obesity characterize a
subgroup of major depressive disorder patients with unfavorable treatment
outcome," they concluded in their study report, which is in press with
"This study confirms earlier findings that depression is associated
with obesity," Gregory Simon, M.D., a psychiatrist and researcher at
Group Health Cooperative in Seattle, told Psychiatric News. Indeed,
in his own study of some 2,300 women, he found that major depression was twice
as prevalent among women with a BMI greater than 30 than in women with a BMI
less than 30 (Psychiatric News, September 16, 2005). "[But]
what's new here," he continued, "is the finding that obesity
predicts poorer response to depression treatment."
Why this is so, however, is open to some speculation. Kloiber and his group
favored a biological explanation because they found that in their overweight
depressed patients, as compared with their normal-weight depressed ones, there
was not just a slower response to antidepressant treatment, but less
improvement in two physiological functions often impaired in depressed
persons—attention and regulation of the
But if biology underlies overweight depressed individuals' response to
antidepressants, what factors might be involved? Cytokines, adipok ines, and
leptin, Kloiber and his team suggested. Cytokines are cell-to-cell signaling
proteins. Adipokines are a group of cytokines secreted by adipose tissue.
Leptin, a protein hormone produced by fat cells, is involved in body-weight
regulation by acting on the hypothalamus to suppress appetite and to burn fat
stored in adipose tissue.
The reasons why they suspect cytokines and adipokines are implicated is
because cytokines and adipokines are known not only to play an important role
in the pathophysiology of obesity, but to interact with the
hypothalamic-pituitary-adrenocortical axis and neurotransmitter systems. They
suspect that leptin might be involved because it is known, besides influencing
appetite and weight regulation, to impact learning, memory, and some other
Although Kloiber and his team focused on biological explanations for the
poorer antidepressant response of overweight depressed individuals, "we
should also consider psychosocial explanations," Simon pointed out."
Obesity leads to a significant burden of self-blame, social isolation,
and activity limitations, all of which may contribute to depression. So we
might think of obesity as a major, ongoing psychosocial stressor that reduces
the likelihood of recovery from depression."
One of this study's findings, however, should give depressed overweight
people a psychological lift. It found that depressed overweight subjects
gained significantly less weight while taking antidepressants than did
depressed subjects of normal weight. The researchers were surprised by this
finding because, as Kloiber explained to Psychiatric News,"
many clinical psychiatry experts consider obese patients to be at
higher risk for additional weight gain during psychopharmacological therapy
compared with normal-weight patients."
The study was funded by the Max Planck Society.
"Overweight and Obesity After Treatment
Response in Major Depression" is posted at<www.journals.elsevierhealth.com/> under Biological Psychiatry.▪