A common underlying genetic contribution to the co-occurrence of depressive symptoms and lower blood pressure in adolescents

Background: Depression and cardiovascular disease risk factors develop in childhood. The objective of this study was to investigate cross sectional and longitudinal associations between blood pressure, mood scores and tagged SNPs within the Monoamine oxidase A (MAOA) gene in the Western Australian Pregnancy Cohort (Raine) Study. Methods: Data from the five (n=1097), eight (n=1046), ten (n=1026) and fourteen (n=1124) year surveys were used. Blood pressure was measured at all surveys, anxious-depressed scores obtained from the Childhood Behavior Checklist at all surveys and depressive symptom scores from the Beck Depression Inventory for Youth at 14 years. Single nucleotide polymorphisms (SNPs) tagging the MAOA gene were identified from HapMap Phase II (CEU) data and genotyped. Cross sectional and longitudinal analyses were used to examine the association between blood pressure (outcome) and tagged SNPs within the MAOA gene and anxious/depressed scores (outcome) and tagged SNPs within the MAOA gene. Results: At 14 years, boys with the risk allele of SNP rs5905859 and rs3027396 had higher systolic blood pressure (βrs5905859=2.5; 95% CI: 0.743, 4.337 and βrs3027396=2.5; 95% CI: 0.681, 4.383 respectively) and lower mood scores (βrs5905859=-0.1; 95% CI: -0.100, -0.022 and βrs3027396=-0.2; 95% CI: -0.313,-0.045 respectively). Longitudinally, boys with the risk allele of SNPs rs5905859 (β=0.3; 95% CI: 0.026, 0.540) or rs6609257 (β= 0.3; 95% CI: 0.022, 0.521) had a higher mean systolic blood pressure trajectory compared to boys without. Conclusions: Variation within or close to the MAOA gene may explain in part the association between lower depressive symptom scores and higher systolic blood pressure in Caucasian boys within the Raine cohort.