Decreased serum levels of polyunsaturated fatty acids and folate, but not brain-derived neurotrophic factor, in childhood and adolescent females with depression

• Not only the serum brain-derived neurotrophic factor (BDNF) levels, but also polyunsaturated fatty acids (PUFAs) and folate are potential biomarkers for depression.
• We determined whether the serum BDNF, PUFAs, and folate levels differ between first-episode child and adolescent depressed patients and healthy controls.
• The serum levels of docosahexanoic acid (DHA), arachidonic acid (AA), and folate were significantly lower in the patients than in the controls.
• The serum levels of BDNF did not differ between the patients and controls.

Evidence from observational studies suggests that there is an association among depression and brain-derived neurotrophic factor (BDNF), polyunsaturated fatty acids (PUFAs), and folate; however, this association has yet to be examined in childhood and adolescent depression. The objective was to determine whether the BDNF, PUFAs, and folate in serum differ between first-episode childhood and adolescent depressed patients and healthy controls. We measured the serum levels of BDNF, PUFAs, and folate of cases admitted to the hospital for depression (n=24) and compared it to that of controls (n=26). Subjects and their parents were informed about the nature and the purpose of this study, and a consent form was signed by parents. The ethics committee of Hirosaki University Graduate School of Medicine approved the study protocol. There were significant differences in the docosahexanoic acid (DHA), arachidonic acid (AA), and folate levels between cases and controls. Serum levels of DHA, AA, and folate levels in the patients group were statistically lower than those in the control group, while serum levels of BDNF were not different between cases and controls. These results are in line with findings of previous studies involving adult and elderly subjects, demonstrating lower levels of PUFAs and folate in patients with depression than healthy controls. However, further studies using larger sample size are warranted.