In a recent study published in The Israel Journal of Psychiatry and Related Sciences, researchers determined that the lack of physical activity, inadequate sleep and hypertension are risk factors for insulin resistance, and that these have the highest association with both depression and diabetes incidence.
Major depression is a heterogeneous disorder, and up to 50% of the individuals diagnosed with the disease have been found to be insulin resistant. There are three primary explanations for comorbidity of these two disorders: i) many behaviours or symptoms associated with depression are established risk factors for insulin resistance, ii) the association between biological mechanisms by which insulin resistance could cause or exacerbate depressed mood, and iii) depression and insulin resistance share some common antecedent such as prenatal exposure to stress or inadequate nutrition.
In the study entitled “Differential Associations Between Depression, Risk Factors for Insulin Resistance and Diabetes Incidence in a Large U.S. Sample”, Dolores Malaspina, MD, from Columbia University, College of Physicians and Surgeons, Department of Psychiatry in New York and colleagues, analysed 10,025 participants from the Epidemiologic Follow-up Studies of the first National Health and Nutrition Examination Survey (NHANES I).
The aim of the study was to investigate the cross-sectional relationships between depression and risk factors for insulin resistance at baseline. Researchers also explored the longitudinal relationships between risk factors for insulin resistance and diabetes incidence.
Ten risk factors for insulin resistance were included in the analysis, namely a body mass index (BMI) greater than 25, physical inactivity, inadequate sleep (less than 6 hours per night), elevated stress, alcohol consumption greater than 2 drinks per day, hypertension, high serum cholesterol, cigarette smoking, age greater than 45 years, and non-Caucasian ethnicity.
The results revealed that depression was cross-sectionally associated with diabetes, however it did not increase the incidence of the condition. A lack of physical activity, hypertension, and inadequate sleep were found to be the most relevant risk factors.
According to the researchers, the contrasting results can be explained by the differing relationships between risk factors for insulin resistance, depression and diabetes. In the article, the team concluded that “given the potential physical and mental health implications, it would be advantageous for health and mental health professionals to bolster their efforts to encourage and motivate their patients who suffer from either diabetes or depression to eat a healthy diet and get adequate amounts of exercise and sleep.”