Low cholesterol is not associated with depression: data from the 2005-2018 National Health and Nutrition Examination Survey

BACKGROUND: Although high serum cholesterol is widely recognized as a major risk factor for heart disease, the health effects of low cholesterol are less clear. Several studies have found a correlation between low cholesterol and depression, but the results are inconsistent. METHODS: Data from the National Health and Nutrition Examination Survey (NHANES) 2005-2018 were utilized in this cross-sectional study. The analysis of the relationship between cholesterol and depression was performed at three levels: low total cholesterol, low high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol. The inclusion criteria were as follows: (1) people with low (<4.14 mmol/L) or normal (4.14-5.16 mmol/L) total cholesterol for Sample 1; people with low (<1 mmol/L) or normal (≥1 mmol/L) HDL cholesterol levels for Sample 2; and people with low (<1.8 mmol/L) or normal (1.8-3.4 mmol/L) LDL cholesterol levels for Sample 3; and (2) people who completed the Patient Health Questionnaire-9 depression scale. Age, sex, educational level, race, marital status, self-rated health, alcohol status, smoking status, body mass index (BMI), poverty income ratio, physical function, comorbidities, and prescription use were considered potential confounders. The missing data were handled by multiple imputations of chained equations. Logistic regression was used to assess the relationship between low cholesterol and depression. RESULTS: After controlling for potential confounding factors in the multivariate logistic regression, no association was observed between depression and low total cholesterol (OR=1.0, 95% CI: 0.9-1.2), low LDL cholesterol (OR=1.0, 95% CI: 0.8-1.4), or low HDL cholesterol (OR=0.9, 95% CI: 0.8-1.1). The results stratified by sex also showed no association between low total cholesterol, low LDL cholesterol, low HDL cholesterol and depression in either men or women. CONCLUSION: This population-based study did not support the assumption that low cholesterol was related to a higher risk of depression. This information may contribute to the debate on how to manage people with low cholesterol in clinical practice.