LOWER DEGREE OF ESTERIFICATION OF SERUM-CHOLESTEROL IN DEPRESSION - RELEVANCE FOR DEPRESSION AND SUICIDE RESEARCH

Previous studies have suggested that depression and suicide are relate d to alterations in total cholesterol serum concentrations, and that a n altered distribution of haptoglobin (Hp) phenotypes in major depress ion indicates that variation on chromosome 16 may be associated with t hat illness. Lecithin:cholesterol acyl transferase (LCAT, EC 2.3.1.43) , the enzyme that catalyzes the esterifying reaction of cholesterol in serum, is located close to the Hp gene. This study examined the serum concentrations of total and free cholesterol and the esterified chole sterol ratio in 26 healthy controls, 47 unipolar depressed subjects (1 6 minor, 14 simple major and 17 melancholic depressed subjects) and 12 relatives of melancholic subjects. Depressed subjects (regardless of subtype) and relatives of depressed subjects had a significantly lower esterified cholesterol ratio than normal controls. No significant dif ferences in total or free cholesterol concentrations were found betwee n the above study groups. In depressed subjects, there were no signifi cant relationships between the esterified cholesterol ratio, total or free cholesterol and postdexamethasone adrenocorticotropic or cortisol values, Hp phenotypes, severity of illness or suicidal symptoms. It i s hypothesized that lower esterification in serum cholesterol may cons titute a vulnerability factor for depression through alterations in ce ll membrane microviscosity.