??Abstract

Background

Previous studies indicate that levels of plasma norepinephrine (p-NE) are altered in depressed patients. However, it is unclear whether altered NE metabolism is involved in the pathogenic association between depression and cardiovascular disease. The aim of the present study was, firstly, to investigate if p-NE levels differ between patients with major depression and healthy controls. Secondly, the study sought to assess the associations between p-NE and metabolic variables in all participants. The third and final aim of the study was to assess if the associations between p-NE and metabolic variables are influenced by disease status (depression vs. healthy).

Methods

108 patients with major depression and 44 healthy controls were tested for levels of p-NE and metabolic variables that affect cardiovascular risk.

Results

The median level of p-NE in depressed patients (DSM-IV) was 2636?pg/ml, (IQR 2094–3143) and 2279?pg/ml (IQR 2007–2562) in non-depressed controls (p?=?0.013). However, the difference between p-NE levels was non-significant when adjusted for daily smoking (p?=?0.138). Significant associations (p?≤?0.05) were observed between p-NE and p-lipids, mean arterial blood pressure, p-insulin, quantitative insulin sensitivity check index as well as inflammatory markers.

Conclusions

Elevated levels of p-NE observed in patients with major depression were attributable to daily smoking, rather than to the depressive disorder. Important associations were found between p-NE and metabolic variables that affect cardiovascular risk. This is interesting from a clinical point of view, since affected individuals may benefit from simple and inexpensive treatments that influence sympathetic activity. All associations were independent of disease status.

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