Obesity appears to be linked with an increased risk of depression, say researchers, and the link also works in the other direction.
Floriana S. Luppino and a team of researchers at Leiden University Medical Center and GGZ Rivierduinen, Leiden, the Netherlands, analyzed the results of 15 previous studies involving 58,745 participants which examined the relationship between depression and obesity over time.
"We found bidirectional associations between depression and obesity: obese persons had a 55% increased risk of developing depression over time, whereas depressed persons had a 58% increased risk of becoming obese. The association between depression and obesity was stronger than the association between depression and overweight, which reflects a dose-response gradient," said the authors.
The researches also found that the link between obesity and later depression was stronger among Americans than among Europeans and stronger for diagnosed depressive disorder compared with depression symptoms.
Although the causes for the obesity-depression link are uncertain, the authors discussed several possible theories, including the following:
- Obesity is an inflammatory state and inflammation increases the risk of depression.
- Obesity contributes to body dissatisfaction and low-esteem, putting the overweight individual at risk for depression.
- Depression may increase weight by either interfering with the endocrine system or through antidepressant side effects.
The authors suggest that doctors treating patients with either depression or obesity should be aware of the link so that they can engage in preventative care and detect problems early.