If you are depressed, there's some new research that isn't likely to boost your mood. Two studies have linked depression both with an increased risk for type 2 diabetes and with increased inflammation, which is tied to a higher risk of heart disease.
In the first study, which appeared in the journal Diabetes Care, a team of Canadian researchers compared history of depression in people over the age of 20 who had been diagnosed with diabetes, with a control group who did not have diabetes. The study was conducted using data from the Saskatchewan Health databases, both to determine whether a person had diabetes and their mental health history. Diagnoses of depression and diabetes were based on diagnostic codes noted in the person's files as well as prescription records.
After controlling for factors such as gender and visits to the doctor, the researchers found the risk of developing diabetes to be 23% higher in people with a history of depression. But while this association existed for people between the ages of 20 and 50, there did not appear to be a link between depression and diabetes for adults aged 51 years and older.
The researchers note that there may be several factors at play in this relationship, including a reduced likelihood for depressed people to exercise or control their weight, as well as the fact that many antidepressant medications may cause weight gain. Excess weight is a proven risk factor for developing type 2 diabetes.
A second study, which was published in the journal Circulation, looked at the relationship between depression and heart disease. While numerous studies have shown that people with a history of depression face an increased risk of developing heart disease, little is understood about the reason for this association. As well, for people already diagnosed with heart disease, depression has been shown to be associated with poorer outcomes and a greater reduction in quality of life.
The study looked at the relationship between depression and inflammation, which has been shown to play a role in the development of heart disease. The researchers looked at data on men from Ireland and France who were enrolled in the Prospective Epidemiological Study of Myocardial Infarction, and compared their history of depression with blood levels of three known markers of inflammation, including C-reactive protein.
All of the people enrolled in the larger study were rated on a scale for depression at the start of the study. About five years later, the researchers identified more than 300 men from the larger study, all of whom had heart disease, and matched them with 585 people in a control group, who were of the same age but did not have heart disease.
According to their analysis, the men who had heart disease were about 9% more likely to score in the fourth quartile on the depression scale. As well, levels of all three inflammation markers were higher in men who were considered to be depressed, even after the researchers accounted for other risk factors for heart disease. "Each inflammatory marker contributed significantly to coronary heart disease event risk," note the researchers.
But the exact mechanisms for the association remain unclear, due to the fact that the relationship between heart disease and depression still existed even after the researchers accounted for differences in inflammation. As a result, the researchers say further studies must be done to explore the nature of the relationship.
In addition to heart disease and diabetes, depression has been linked with a number of other health problems, including reduced immunity and increased stroke risk - underscoring the importance of seeking treatment for depression or encouraging someone you know who is suffering from the condition to get help.
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