New research from Japan may help cheer up young adolescent boys dealing with symptoms of depression. In a recent article published in the Journal of the American Academy of Pediatrics, researchers found that increased intakes of fatty fish were associated with fewer depressive symptoms in teenage boys aged 12 to 15. Similar results were not seen for teenage girls, however.
Fish such as salmon, trout, and whitefish are good sources of the omega-3 polyunsaturated fatty acids EPA and DHA. Fatty fish, such as sardines, mackerel, yellowtail, and tuna are especially high in these healthy fatty acids.
Researchers performed a cross-sectional analysis of over 6,500 Japanese junior-high students in order to observe a possible link between fish, EPA, and DHA intakes and symptoms of depression in the teenagers. The researchers gave the adolescents a diet-history questionnaire to determine their intake of fish, EPA and DHA over the previous month. They were also given a lifestyle questionnaire to assess physical fitness levels, family dynamics, and parents’ education levels, and depressive symptoms were scored using a previously-validated scale. Based on the questionnaires, they found that about 23 percent of the teenage boys and 31 percent of the teenage girls experienced symptoms of depression.
As EPA was increased in the diet, the depressive symptoms decreased. DHA intake showed a directionally similar, but less significant, association. Combined EPA and DHA intakes were also related to lowering depressive symptoms.
Overall, the researchers found that teen boys experiencing depression were more likely to:
- Exercise less
- Have fathers with higher education levels and live with both parents
- Have a higher body mass index (BMI; kg/m2)
- Have a lower intake of fish, EPA, and DHA
Due to the nature of the study design, however, it is impossible to determine the direction of these relationships. In other words, it’s unclear whether pre-existing depression may cause teen boys to exercise less, and gain more weight, or whether these factors are contributing causes to the depression.
Girls experiencing depression were also more likely to exercise less, have mothers and fathers with high education levels, and live with their fathers. The fact that higher levels of EPA and DHA were associated with fewer symptoms of depression in teenage boys and not teenage girls may be explained by the fact that depression is more genetically linked in females. As a result, its possible that dietary or lifestyle habits could have less influence on the prevalence of depression in girls.
Depression is considered a major public health concern and a leading risk factor for morbidity and mortality in developed countries. Previous research has focused on western adult populations. This study is the first published analysis of symptoms in Japanese youth. While more studies are needed to clarify which symptoms found in study participants are associated with true clinical depression – rather than general fatigue, for example – and whether symptoms found in this study’s population are regionally or culturally specific, the results offer a solid foundation for future work on depression in this age group.