Association between blood manganese levels and depressive symptoms among US adults: A nationally representative cross-sectional study.

BACKGROUND: Recent studies indicated that manganese (Mn) levels were inconsistently associated with the prevalence of depression. We aimed to evaluate whether blood Mn concentrations were associated with the risk of depression among US adults. METHODS: Using the NHANES 2011-2019 datasets, we conducted a cross-sectional study in 16,572 eligible participants with complete data on blood Mn concentrations and depression diagnosis. A weighted multivariable logistic model and restricted cubic spline model were applied to explore the association and dose-response relationship of blood Mn concentrations with depression risk in the total population and subgroups. RESULTS: In the total population, compared with the lowest reference group of blood Mn, participants in the second, third, and fourth quartile had an OR of 0.84 (95%CI: 0.66, 1.07), 0.93 (95%CI: 0.73, 1.19) and 0.91 (95%CI: 0.71, 1.15) for depression (ptrend = 0.640). In subgroup analyses, doubling of blood Mn concentrations was associated with a 0.83-fold (95%CI: 0.67, 1.02), 0.30 -fold (0.14, 0.65) decreased risk of depression in females and other ethnic groups, respectively. Significant modification effects of ethnicity on the association of blood Mn concentrations with depression risk were observed. LIMITATIONS: cross-sectional study design and self-reported depressive symptoms. CONCLUSIONS: Elevated blood Mn concentrations were associated with decreased depression risk in females and other specific subgroups. Mn supplementation could be a potential pathway for intervention and prevention of depression.

[Microscopic raman imaging spectra of realgar and light-induced degradation products in realgar].

Light-induced degradation in realgar was studied by means of Raman spectroscopy. The result substantiated the following reaction: An additional S atom is inserted between the As atoms in the As4S4 molecule because As--As bonds are weaker than As--S bonds. It is likely that the resulting As--S--As molecule is too unstable to exist. Furthermore, an S atom in the As4S5 molecule is released from one of the equivalent As--S--As linkages in As4Ss which becomes the As4S4 molecular of pararealgar. After the As4S5 molecule is divided into an S atom (radical) and the As4S4 (pararealgar type) molecule, the free S atom is re-attached to another As4S4 (realgar type) molecule, reproducing an As4S5 molecule. The reproduced As4S5 molecule is again divided into an S atom (radical) and an As4S4 (pararealgar type) molecule. This cycle whereby realgar is indirectly transformed into pararealgar via the As4S5 molecule is promoted by light and repeated during light exposure.