BACKGROUNDMajor depression is classified into distinct subtypes: simple (SDMD) and major dysmood disorder (MDMD). MDMD patients exhibit elevated atherogenicity and decreased reverse cholesterol transport (RCT). However, comprehensive data regarding lipid metabolism is absent in first episode (FE)-SDMD.AIMSIn this case-control study, plasma lipid levels, lecithin-cholesterol acyltransferase (LCAT), free cholesterol, apolipoprotein (Apo)A1, ApoB, and ApoE are compared between academic students with first episode SDMD (FE-SDMD) (n = 44) or SDMD (n = 64) and control students (n = 44), after excluding those with metabolic syndrome (MetS).RESULTSLCAT is decreased, and free cholesterol and ApoE increased in subjects with SDMD and FE-SDMD as compared with controls. There were no significant alterations in high-density lipoprotein cholesterol (HDLc), ApoA1, RCT, ApoB and triglycerides in SDMD. LCAT, free cholesterol and atherogenicity indices are significantly associated with suicidal behaviors and the SDMD phenome. The effects of LCAT on those phenome features is completely mediated by free cholesterol and brooding. SDMD and FE-SDMD patients without signs of subclinical MetS show lowered LCAT and increased free cholesterol as compared with normal controls. There are significant interactions between the SDMD and FE-SDMD diagnosis and subclinical MetS, which result in decreased HDLc and RCT, and an increased ApoB/ApoA ratio.DISCUSSIONFE-SDMD and SDMD are pre-proatherogenic states, because of decreased LCAT, and increased free cholesterol and ApoE, and their intersections with subclinical MetS. These aberrations may drive atherogenicity, and activation of peripheral and central oxidative, neuro-immune, and degenerative pathways. Individuals with FE-SDMD should be screened and treated for increased atherogenicity risk by measuring free cholesterol and ApoE.