Evidence linking omega-3 fatty acid deficiencies to mood disorders was demonstrated in two recent studies, with diminished EPA and DHA levels being suggested as modifiable risk factors or prodromal biomarkers for depressive illness in adolescents.[1,2]
In a 2016 study, erythrocyte fatty acid composition was analysed in four separate groups of adolescents: healthy adolescents (healthy control or HC; n = 28), asymptomatic adolescents with a biological parent with bipolar disorder (high risk or HR; n = 30), adolescents with a biological parent with bipolar and depression (ultra-high risk or UHR; n = 36), and first episode adolescent bipolar manic patients (bipolar patients or BP; n = 35).1
The BP and UHR groups had significantly lower erythrocyte levels of EPA and DHA, compared to the control group (p ≤ 0.0001 and p = 0.0006, respectively). Levels in the HR group were also lower, but not to a statistically significant outcome (p = 0.06). In the control group, 61% had erythrocyte fatty acid levels below or equal to 4%; however, these low levels were more prevalent in the other groups, reaching statistical significance in all cases: HR 77% (p = 0.02), UHR 80% (p = 0.005) and BP 97% (p = 0.001).
In all groups, low EPA and DHA levels were associated with manic and depressive symptom severity. Low levels coincided with the initial onset of mania and graded deficits were linked with increased risk of bipolar disorder. The authors concluded “Low erythrocyte EPA + DHA biostatus may represent a promising prodromal risk biomarker...”
The same principal authors of this study published further findings in 2017, which analysed the effect of fish oil supplementation on adolescents with major depressive disorder.
During childhood and adolescence, there are rapid changes in the prefrontal cortex structure and functional maturation, with greater requirements for DHA. According to previous research, the link between low omega 3 fatty acid status and alterations in this part of the brain are commonly observed in depression and mood disorders.
In this newer study, proton magnetic resonance spectroscopy (1H MRS) was conducted on adolescent depressives taking SSRIs, to measure the effect of low or high dose omega 3 fatty acids on cortical metabolite concentrations. To do this, they were randomised to receive either 2.4 grams of EPA/DHA (n = 7) or 16.2 grams EPA/DHA (n = 7) per day for ten weeks.
The results showed that both dosing groups had significantly increased EPA and DHA fatty acid status. Depressive symptoms were significantly reduced in the high dose group only (p > 0.0001), although there was a trend towards statistical reduction in the low dose group (p = 0.06).
These changes were not supported with robust alterations in cortical metabolite concentrations of the brain; however, the results identified cortical regions that may be more sensitive to fatty acid status with further investigation needed to find the exact mechanism.
- McNamara RK, Jandacek R, Tso P, et al. Adolescents with or at ultra-high risk for bipolar disorder exhibit erythrocyte docosahexaenoic acid and eicosapentaenoic acid deficits: a candidate prodromal risk biomarker. Early Interv Psych 2016;10(3):203-211. [Full Text]
- McNamara RK, Jandacek R, Rider T, et al. Effects of fish oil supplementation on prefrontal metabolite concentrations in adolescents with major depressive disorder: a preliminary 1H MRS study. Nutr Neurosci 2016;19(4):145-155. [Full Text]