Background: Several studies have suggested that late-onset depressive disorder (LOD) and the apolipoprotein E (Apo E) epsilon 4 allele are associated with dementia, respectively. The Apo E polymorphism is significantly heterogeneous among races. We hypothesized that the Apo E epsilon 4 allele frequency is elevated in Japanese LOD.
Methods: The Apo E genotype was studied in 134 patients (male, 53; female, 81) with early-/late-onset depressive disorder and 105 healthy normal controls (male, 41; female, 64). The patients were subdivided into those with early onset and late onset using 45 and 50 years as the cutoff ages. All the subjects were Japanese.
Results: There was statistically no difference between normal control subjects and patients with depressive disorders in Apo E genotype or allele frequency. There was statistically no difference in the age of onset of depressive disorders according to the Apo E genotype. There was no relation between the age of onset of depressive disorder and the number of epsilon 4 alleles the patient had. There was also no association between early-/late-onset depressive disorder and the Apo E genotype or allele frequency.
Conclusions: Our results suggest that there is no association between the Apo E epsilon 4 allele and Japanese LOD.