A collaborative effort led by researchers at McGill University, Canada, suggested that depression could be a risk factor for the development of type 2 diabetes in people with early signs of metabolic problems, like obesity, unhealthy cholesterol, or elevated blood pressure.
The findings, published in the journal Molecular Psychiatry, were in a study titled “Depression and risk of type 2 diabetes: the potential role of metabolic factors“.
“Emerging evidence suggests that not depression, per se, but depression in combination with behavioral and metabolic risk factors increases the risk of developing type 2 diabetes and cardiovascular conditions,” Norbert Schmitz, an associate professor in McGill’s Department of Psychiatry and a researcher at its affiliated Douglas Mental Health University Institute, said in the press release. “The aim of our study was to evaluate characteristics of individuals with both depressive symptoms and metabolic risk factors.”
A total of 2,525 people, ages 40 to 69, were included in the 4.5-year study, which took place in Quebec. Participants were divided into four groups: those with both depression and three or more metabolic risk factors, those with depression only, those with metabolic risk factors only, and a control group with neither condition.
Results showed that participants with depression alone were not at a higher risk of developing diabetes when compared to the reference group. But the risk of developing the disease increased four-fold in those with metabolic risk factors, and by more than six-fold in participants with both depression and metabolic risk factors.
Data analysis also revealed that the combined effect of depression and metabolic symptoms was higher than the sum of its separate effects. The researchers proposed several hypotheses to justify these results.
One relies on the behavioral synergistic effects between the two risk factors. A number of studies have shown that individuals with depression poorly manage their metabolic problems in terms of medical treatment, diet, and lifestyle changes. This may aggravate metabolic symptoms that, in turn, exacerbate the depression, in a vicious cycle. Another is the impact of depression on the metabolic process. It is well-known that some types of depression, either left untreated or treated with antidepressant medicines, may alter some metabolic processes, increasing the risk of diabetes.
The researchers believe better identification of people with both depression and metabolic problems is necessary to allow proper treatment and reduce risk.
“Focusing on depression alone might not change lifestyle/metabolic factors, so people are still at an increased risk of developing poor health outcomes, which in turn increases the risk of developing recurrent depression,” Dr. Schmitz, the study’s lead author, concluded.
The World Health Organization estimates that about 8.5 percent of adults worldwide have diabetes. The largest portion of these diabetic patients (about 90 percent) suffers from type 2 diabetes, a condition characterized by insulin resistance. Type 2 diabetes is often linked to excess weight or obesity and a lack of physical exercise.