"Depression has been associated with the onset of diabetes, cardiovascular disease and cardiac mortality [death]. To better prevent occurrence of these major disabling and life-threatening diseases, more insight into underlying mechanisms relating depression to these disorders is needed," wrote the authors.
In the study, led by Nicole Vogelzangs, M.Sc., of VU University Medical Center, Amsterdam, the Netherlands, researchers analysed 2,088 adults age 70 to 79 years.
All the participants were screened for depression at the beginning of the study and their overall and abdominal obesity was recorded then and again after five years. Measures of overall obesity included body mass index and body fat percentage, while abdominal obesity was assessed using waist circumference, sagittal diameter (distance between the back and the highest point of the abdomen) and visceral fat (fat between the internal organs) measured by computed tomography.
The scientists observed that at the beginning of the study, 4 percent of participants had depression. After adjusting for sociodemographic and other characteristics associated with weight changes, depression was linked with an increase in sagittal diameter and visceral fat over five years.
"Such an association was not found for an increase in overall obesity and also appeared to be independent of changes in overall obesity, suggesting that depressive symptoms are rather specifically associated with fat gain in the visceral region," wrote the authors.
The authors indicated that there are several mechanisms by which depression might increase abdominal fat.
Chronic stress and depression may activate certain brain areas and lead to increased levels of the hormone cortisol, which promotes the accumulation of visceral fat. Individuals with depression may have unhealthier lifestyles, including a poor diet that could interact with other physiological factors to produce an increase in abdominal obesity.
The authors concluded: "Our longitudinal results suggest that clinically relevant depressive symptoms give rise to an increase in abdominal obesity, in particular visceral fat, which seems to be stronger than and independent of overall obesity. This could also help explain why depression is often followed by diabetes or cardiovascular disease. Future research should further disentangle these mechanisms because this will yield important information for prevention or treatment of depression-related health consequences."
The study is published in the December issue of Archives of General Psychiatry, one of the JAMA/Archives journals.