Coronary artery disease and depression: Possible role of brain-derived neurotrophic factor and serotonin transporter gene polymorphisms

Cardiovascular disease (CVD) and depression are two of the most common human health problems. Patients with depression have an increased risk of developing cardiovascular disease and mortality after experiencing a cardiac event. Both diseases are complex disorders that are influenced by genetic and environmental factors. Brain-derived neuro-trophic factor (BDNF) plays a critical role in regulating both vascular development and response to injury, and promotes survival, differentiation, and maintenance of neurons in the peripheral and nervous system. Evidence suggests that BDNF can enhance serotoninergic transmission. Serotonin modulates different brain functions and is known to regulate sleep, appetite, pain and inflammation. The aims of the present case-control study were to investigate the possible role of BDNF Val66Met, 5-HTTLPR and -1438 G/A polymorphisms in the development of coronary artery disease (CAD) in patients with and without depression. Regarding BDNF, our data suggest an involvement of the AA genotype in the pathogenesis of CAD in females and in the predisposition to CAD associated with depression. Furthermore, it could be argued that the GG genotype is protective against CAD in the female population and against CAD associated with depression. In our CAD population we also observed a significant increase in the L/L genotype and a decrease in the S/L genotype with respect to the controls. A higher frequency of the L allele, responsible for enhancing the efficiency of transcription, was found in CAD patients. These findings may be responsible for the increased capacity of platelet serotonin uptake previously observed in patients with CAD. Although no differences were found for genotype and allelic frequencies of the -1438 G/A polymorphism between the CAD patients and controls, we cannot exclude the possible role of this receptor in coronary artery disease.