Polymorphism v1

Background: Depressive symptoms are diagnosed using symptom scales by a psychiatric doctor but pathophysiology is unclear. Serotonin (5-HT) plays an important role in neural activity and social behavior. 5-HT transporter (5-HTT) is an important regulator of brain serotonin levels and its reuptake. The 5-HTT gene-linked polymorphic region (5-HTTLPR) is associated with depression. Aim: The aim of this study was to further characterize the role and impact of serotonin levels in plasma and the 5HTTPLR polymorphism in the depressive symptoms present in older adults. Methods:We included 84 aging adult participants. Plasma serotonin levels was determined by ELISA method and the 5-HTTLPR genotype was analyzed by polymerase chain reaction (PCR). Results and discussion:33 (39.3%) participants presented with depressive symptoms. The median level of serotonin in blood was 204.34 ± 93.88 ng/mL. There was an association between plasma serotonin levels and depressive symptoms (p= 0.001). The 5-HTTLPR analysis showed that of the 84 older adults, 30 (35.7%) were SS genotype, 9 (10.7%) LL genotype and 45 (53.6%) heterozygous. No association was found between the 5-HTTLPR polymorphism and depressive symptoms; (odds ratio) OR 1.21 95%IC 0.6-2.30 and plasma serotonin levels OR 0.73 95%IC 0.39-1.38. Conclusions:Depressive Symptomsare associated with low serotonin levels in the plasma but not with a 5-HTTLPR polymorphism in a population of aging Mexican adults. There was also a protective effect against depressive symptoms associated with high serotonin levels in the presence of the S allele.