Association of the Apolipoprotein E Gene, Its Promoter Polymorphisms and Haplotypes with Depressive Symptoms

OBJECTIVES: Evidence on apolipoprotein E (APOE) gene as a vulnerability factor for depression is mixed. Polymorphisms of the APOE gene regulatory region may serve as additional explanatory factors, as they help in explaining variation of depressive symptoms within the APOE epsilon2/epsilon3/epsilon4 genotype groups. In this study, the associations of the APOE gene promoter polymorphisms -219G/T and +113G/C and their haplotypes with depressive symptoms were examined. METHODS: The data is from a subpopulation of 660 young adults (24-39 years old) of the ongoing population-based Cardiovascular Risk in Young Finns Study. Depressive symptoms were assessed by a revised version of Beck's Depression Inventory. Clinical screening assessed lipid levels and other known physiological and behavioral risk factors for depressive symptoms. RESULTS: The APOE epsilon4 allele was not related to depressive symptoms. Similarly, no statistically significant associations were found between the APOE gene promoter -219G/T and +113G/C polymorphisms and depressive symptoms. Within theAPOE epsilon3/epsilon3 genotype subgroup (n = 373), carriers of both -219G/+113C and -219T/+113G haplotypes (GC/TG) had higher depressive symptoms compared to noncarriers of these haplotypes (2.52 vs. 1.98; p = 0.002). This relationship persisted after separate adjustments for various risk factors including sex, age, LDL cholesterol, HDL cholesterol, triglycerides, total cholesterol, C-reactive protein, systolic blood pressure, body mass index and alcohol consumption. CONCLUSIONS: Our results suggest that the APOE gene does not predispose carriers to depressive symptoms among healthy young adults. However, the promoter haplotype GC/TG may elevate the risk of depressive symptoms.