Association between the change of total cholesterol during adolescence and depressive symptoms in early adulthood.

Increasing evidence suggests that serum lipids are associated with depressive symptoms. However, previous studies have mostly employed a cross-sectional design and assessed middle-aged or older adult populations, making it difficult to discern the impact of lipid changes early in life on the development of depression. Accordingly, we sought to investigate changes in blood cholesterol levels during adolescence and the development of depressive symptoms in early adulthood. This prospective cohort study included participants aged 15-16 years from the JS High School Study (JSHS), with an average follow-up of 6 years. Participants had no diagnosed depression at baseline. Multivariable linear regression models were used to estimate associations between changes in total cholesterol during adolescence and depressive symptoms in adulthood. Changes in total cholesterol during adolescence were classified as "consistently low," "decreased," "moderate," "increased," or "consistently high". In men, depressive symptoms were higher in the consistently low (β = 3.20, p = 0.036) and increased total cholesterol groups (β = 3.48, p = 0.017), compared with the moderate group. In the consistently high group, although a positive linear association was observed, it lacked statistical significance (β = 2.71, p = 0.067). While similar tendencies were noted in women, the associations were not statistically significant. Consistently low or increased total cholesterol levels during adolescence may pose an increased risk of depressive symptoms in early adulthood. These findings suggest that different strategies should be adopted to manage the lipid risk factors with consideration of age and sex.