Gender differences in the association between adiposity and probable major depression: a cross-sectional study of 140,564 UK Biobank participants

<b>Background</b><p></p> Previous studies on the association between adiposity and mood disorder have produced contradictory results, and few have used measurements other than body mass index (BMI). We examined the association between probable major depression and several measurements of adiposity: BMI, waist circumference (WC), waist-hip-ratio (WHR), and body fat percentage (BF%).<p></p> <b>Methods</b><p></p> We conducted a cross-sectional study using baseline data on the sub-group of UK Biobank participants who were assessed for mood disorder. Multivariate logistic regression models were used, adjusting for potential confounders including: demographic and life-style factors, comorbidity and psychotropic medication.<p></p> <b>Results</b><p></p> Of the 140,564 eligible participants, evidence of probable major depression was reported by 30,145 (21.5%). The fully adjusted odds ratios (OR) for obese participants were 1.16 (95% confidence interval (CI) 1.12, 1.20) using BMI, 1.15 (95% CI 1.11, 1.19) using WC, 1.09 (95% CI 1.05, 1.13) using WHR and 1.18 (95% CI 1.12, 1.25) using BF% (all p <0.001). There was a significant interaction between adiposity and gender (p = 0.001). Overweight women were at increased risk of depression with a dose response relationship across the overweight (25.0-29.9 kg/m2), obese I (30.0-34.9 kg/m2), II (35.0-39.9 kg/m2) and III (≥40.0 kg/m2) categories; fully adjusted ORs 1.14, 1.20, 1.29 and 1.48, respectively (all p < 0.001). In contrast, only obese III men had significantly increased risk of depression (OR 1.29, 95% CI 1.08, 1.54, p = 0.006).<p></p> <b>Conclusion</b><p></p> Adiposity was associated with probable major depression, irrespective of the measurement used. The association was stronger in women than men. Physicians managing overweight and obese women should be alert to this increased risk

Reconstructing geochemical conditions during dolomite formation in a Carnian coastal sabkha using 87Sr/86Sr isotopes - Travenanzes Formation, northern Italy

The geochemical conditions that were conducive to primary dolomite formation in extremely shallow evaporitic environments along the Triassic Tethyan margin are still poorly understood. While the massive Triassic dolomites in the Austroalpine and South Alpine realm are largely affected by diagenetic or hydrothermal overprint, Preto et al. (2015) provide evidence of primary dolomite based on nano-crystal aggregates observed under the transmission electron microscope. These dolomites are intercalated in a 100-m-thick sequence of clay (Travenanzes Formation, Southern Alps), deposited on a semi-arid coastal plain in the Late Carnian (Tuvalian II). They may serve as a geochemical archive of evaporative brine composition at the time of dolomite formation. Petrographic and field observations revealed that dolomites occur as three different types, (1) dm- to mthick homogenous beds, (2) mm-scale laminated (stromatolitic) beds and (3) nodules associated with root traces and palaeosols. In all types, the dolomite is stoichiometrically and structurally well ordered. While the homogeneous dolomites occasionally show a peloidal structure, all types of dolomite are generally microcrystalline. Soft sediment deformation, or brittle deformation with mud infill indicates that the dolomitic sediment was largely unlithified at the time of deposition. We analysed the dolomites under the SEM in backscatter mode and observed largely anhedral structures with grain sizes in the m-range. The laminated dolomites consist of mm- to cm-scale clay-dolomite alternations, whereby the dolomite often shows a spherulitic growth near the dolomite-clay interface, where further recrystallization was inhibited. We measured strontium isotope ratios (87Sr/86Sr) as an indicator for the source of alkalinity driving dolomite precipitation. Our data are in a range between 0.707672 (homogenous dolomite) and 0.707976 (both 2: 4*10-5) (nodular dolomite) indicating a similar trend as in Triassic seawater during the Carnian (Korte et al., 2003). 87Sr/86Sr ratios of homogenous dolomite beds and peloidal grainstone plot near to the seawater curve indicating a formation of dolomite in a lagoonal or intertidal environment influenced by evaporating sea water. Synsedimentary deformation and reworking of some laminae may indicate tidal currents or storm events. Cuspate-upward deformed lamination most likely results from desiccation cracks. Laminated dolomites are slightly more radiogenic than the seawater curve, indicating an influence of continental groundwater as observed by M\ufcller et al. (1990) in the landward parts of the modern Sabkha of Abu Dhabi. A bit more radiogenic values occur in the nodular dolomites associated with palaeosols and large amounts of clay. Presumably, these palaeosols formed at times of seawater lowstand when the supratidal flat was subject to more continental influence. At the same time, dolomites from the Germanic Keuper Basin (also Upper Triassic) are much more radiogenic and were clearly formed by continental groundwater as an ionic source. In conclusion, 87Sr/86Sr-ratios very well match the sedimentary conditions in a sabkha with seasonally humid episodes as suggested by the palaeoenvironmental reconstructions. This confirms that ancient primary dolomites can indeed serve as geochemical archives

Reconstructing conditions during dolomite formation on a Carnian coastal sabkha/alluvial plain using 87Sr/86Sr isotopes - Travenanzes Formation, northern Italy

The study of large amounts of dolomite that formed in the Triassic Tethyan realm is hampered by late diagenetic or hydrothermal overprint. These dolomites are difficult to link to past environmental and early diagenetic conditions, and their correlation to models for dolomite formation in modern environments is problematic. Preto et al. (2015) suggested, based on evidence from nano-scale structure analysis by transmission electron microscopy and petrographic observations, that dolomites in the Carnian Travenanzes Formation of the Southern Alps (Dolomites area) represent a preserved primary phase. The Travenanzes Formation was deposited in an extended alluvial plain or coastal sabkha environment subject to a semi-arid climate. Beds and nodules of nearly stoichiometric dolomite are embedded in large amounts of clay, which shielded early formed dolomite from diagenetic fluids. This finding of penecontemporaneous dolomite provides an ideal model case for reconstructing past environmental conditions at the time of dolomite precipitation. While Preto et al. (2015) argued that dolomite formation was mediated by extracellular polymeric substances produced by sulphate-reducing bacteria, it remains unclear whether precipitation occurred from evaporating seawater or mainly from brine derived from evaporating continental groundwater. Both cases exist in modern environments of dolomite formation. In the coastal sabkhas of Abu Dhabi and Qatar, dolomite precipitates from concentrated brine derived from seawater, either through seepage and reflux or through evaporative pumping (the sabkha model). In the coastal ephemeral lakes of the Coorong Lagoon system (South Australia) dolomite precipitation occurs from evaporating groundwater. The goal of this study is to distinguish marine from continental influence during formation of Carnian dolomite using 87Sr/86Sr isotope ratios. Sr isotopes could reveal different origins of ionic solutions for dolomite precipitation, which is not indicated by oxygen isotopes. The marine 87Sr/86Sr values have been reconstructed for most of the Phanerozoic and are nearly constant in the Carnian (McArthur et al., 2012), while the age of the dolomite beds of the Travenanzes Formation is constrained by their stratigraphic position in the measured section (Dibona Section; Preto et al., 2015). The continental Sr isotope signal is governed by weathering rates, especially during silicate weathering of the source rock in the catchment area (McArthur et al., 2012). Through 87Sr/86Sr isotope investigation of primary dolomite in beds and nodules of the coastal sabkha or alluvial plain environment, the influence of marine or continental conditions can be determined. The finding of celestine SrSO4 and Sr-rich barite BaSO4 within the cemented dolomite by SEM indicates enrichment of Sr, possibly during strong evaporative conditions. Hence, the generation of phase-specific Sr-isotope data will allow for a more precise reconstruction of the conditions that led to dolomite formation in the Triassic shallow coastal sabkha/alluvial plain environment