Objectives: The purpose of the present study was to investigate the serum levels of endocannabinoids (eCBs; anandamide: AEA and 2-arachidonoylglycerol: 2-AG) and daily intake of polyunsaturated fatty acids (PUFAs; arachidonic acid: ARA, docosahexaenoic acid: DHA, and eicosapentaenoic acid: EPA) among subjects with high and low depressive symptoms.
Methods: The participants comprised female community-dwellers aged 40 years or older in Japan. Among 208 females, fourteen participants with high depressive symptoms and ten participants with low depressive symptoms were selected for this study. The depressive symptoms were measured by the Japanese version of the Centre for Epidemiologic Studies Depression Scale (CES-D). The daily intake of PUFAs were assessed utilising the brief-type self-administered diet history questionnaire. The blood samples were analysed for AEA, 2-AG, and the CB receptor 1 gene (CNR1) single nucleotide polymorphism (SNP) rs806377.
Results: The ratio of AEA serum level to ARA intake (AEA/ARA) in high depressive participants was significantly higher compared with those in low depressive participants even after controlling for confounders, whereas there were no significant differences in the serum concentrations of eCBs, daily intake of PUFAs, as well as the CNR1 SNP (rs806377) between the high and low CES-D scored groups.
Conclusion: The elevated level of AEA/ARA among high depressive participants suggests that the conversion rate of ARA to AEA may be accelerated in depressive individuals.