Association between increased plasma levels of homocysteine and depression observed in individuals with primary lactose malabsorption.

BACKGROUND: Current literature proposes associations between homocysteine (HCY), folic acid (FA), vitamin B12 metabolism and depression. However, the exact underlying biological mechanisms remain unclear. This study aimed at evaluating a possible link between primary adult-type lactose malabsorption (PALM), HCY, FA and vitamin B12 metabolism and depressive disorder. METHODS: Plasma levels of HCY, FA and vitamin B12 were determined in 78 patients with PALM and 160 individuals with lactase persistence sub-grouped by the presence or absence of major depression. RESULTS: In 78 patients with PALM, the subgroup of 22 individuals with major depression showed significantly higher median (interquartile range) HCY (10.10 [8.46-12.03] vs. 8.9 [7.54-9.86] µmol/L, p = 0.029) and lower plasma FA levels (5.7 [4.68-9.14] vs. 6.95 [5.24-10.56] µmol/L, p = 0.272) compared to the subgroup of 56 individuals without depression, respectively. No such associations could be observed for those 160 individuals without PALM (i.e., lactase persistence) Plasma HCY levels were positively correlated with depressive symptoms (p = 0.052), and showed negative correlations with FA (p = < 0.001) and vitamin B12 (p = 0.029), respectively. CONCLUSION: Depressed individuals with PALM were found with significantly higher HCY and lower FA levels compared to non-depressed individuals with PALM, however, this association was absent in the subgroup of lactase persistent individuals. These findings suggest an association between increased HCY levels, lactose malabsorption and depression.

Prospective plasma lipid profiling in individuals with and without depression.

BACKGROUND: So far, studies on possible association of plasma lipid levels and depressive disorder are contradictory. This prospective work aimed at assessing a plasma lipid profile in individuals with major depression and healthy controls. METHODS: In total, 94 patients with major depression and 152 healthy controls were included in this prospective study. After an overnight fasting state of 12 h they underwent blood drawing for triglyzerides (TG), total cholesterol, low-density lipoprotein (LDL)- and high-density lipoprotein (HDL)-cholesterol measurements. All participants were evaluated in a clinical interview and filled out the self-rating Beck Depression Inventory (BDI-II) scale to identify depressive symptomatology. RESULTS: Ninety-four patients with major depression showed significantly higher median (interquartile range) plasma TG levels (108.0 [75.8-154.1] vs. 84.0 [63.0-132.2] mg/dL, P = 0.014) and significantly lower HDL-cholesterol levels (55.0 [46.9-123.0] vs. 61.5 [47.4-72.6] mg/dL, P = 0.049) compared to 152 individuals without depression, respectively. Total and LDL-cholesterol concentrations were observed slightly higher in patients with major depression. Significant positive correlation was found between TG, total cholesterol and LDL-cholesterol concentrations and the BDI-II score (p = 0.027, 0.048 and 0.018), and in tendency negative correlation between HDL-cholesterol levels and the BDI-II score (P = 0.091), respectively. CONCLUSIONS: Depressive individuals were found with adverse plasma lipid patterns of higher TG and lower HDL-cholesterol levels compared to healthy controls. On this basis, the authors would suggest the implementation of routine lipid measurements in order to stratify these patients by their cardiovascular risk.

Assessment of tryptophan metabolism and signs of depression in individuals with carbohydrate malabsorption.

This prospective cross-sectional study aimed to investigate the potential association between primary-adult lactose malabsorption, fructose malabsorption, tryptophan (TRP) metabolism and the presence of depressive signs. Overall 251 patients, who were referred for lactase gene C/T-13910 polymorphism genotyping and fructose hydrogen/methane breath testing, were included. All participants filled out the Beck Depression Inventory (BDI II). Serum concentrations of tryptophan (TRP), kynurenine (KYN), kynuric acid (KYNA), and TRP competing amino acids (leucine, isoleucine, valine, phenylalanine, tyrosine) were measured by high-pressure liquid-chromatography. Logistic regression analysis was performed with lactose malabsorption, fructose malabsorption and all potential biomarkers of TRP metabolism to assess the effect on signs of depression, defined as a BDI II score > 13. Primary-adult lactose malabsorption and fructose malabsorption was detected in 65 (25.90%) and 65 (25.90%) patients, respectively. Fructose malabsorption was significantly associated with BDI II score, whereas no such relationship was found for lactose malabsorption. Serum levels of TRP and TRP metabolites were no predictors of depression. The authors suggest to conduct further prospective longitudinal studies in order to get further insight of associations between carbohydrate malabsorption, biomarkers and mood disorders.