Background: Spermidine, a natural polyamine, appears to be a promising intervention for the treatment of obesity in animal studies, but epidemiological studies on the association between spermidine and obesity are inadequate. Methods: In the cross-sectional study, a total of 4230 eligible Chinese rural participants aged ≥ 35 years at baseline were recruited, of whom 1738 completed the two-year follow-up. Serum spermidines were measured using high-performance liquid chromatography with a fluorescence detector. Obesity and change in BMI were used as outcomes. Multivariable logistic regression analysis was applied to obtain the odds ratios (ORs) and 95% confidence intervals (CIs). Results: Participants who were obese had higher serum spermidine concentrations than those who were of normal weight (median (IQR), 27.2 ng/mL (14.8–53.4 ng/mL) vs. 23.8 ng/mL (12.8–46.6 ng/mL), p = 0.002). Compared with participants in the first quartile, those in the third quartile (OR 1.327, 95% CI 1.050 to 1.678) and the fourth quartile (OR 1.417, 95% CI 1.121 to 1.791) had a significantly increased risk of prevalent obesity after adjustment for confounding factors. In the follow-up study, participants in the third quartile (OR 0.712, 95% CI 0.535 to 0.946) and the fourth quartile (OR 0.493, 95% CI 0.370 to 0.657) had significantly lower risks of an increase in BMI after adjustment for confounding factors, with the lowest quartile as the reference. Meanwhile, we found a nonlinear relationship between spermidine and BMI in the follow-up study (p < 0.001). Conclusions: Serum spermidine was positively associated with increased odds of obesity in the cross-sectional study but reduced odds of an increase in BMI in the follow-up study among Chinese adults. Future studies are warranted to determine the exact mechanism underlying the association between spermidine and obesity and the scope for interventions.

BackgroundMild cognitive impairment (MCI), a reversible intermediate state, plays an important role in the development and prevention of dementia. The relationship between pulmonary function and MCI risk has not yet been well-elucidated.MethodsWe included 2,947 rural Chinese residents aged ≥35 years who were free from a history of stroke, dementia, or other brain diseases and measured pulmonary ventilatory function using calibrated spirometry according to the recommended method. MCI was assessed with the Montreal Cognitive Assessment-Basic for Chinese scale. Logistic regression models and restricted cubic splines with covariate adjustment were performed to explore the association between pulmonary function and MCI risk.ResultsThe prevalence of MCI increased with decreasing pulmonary function, from the lowest quartile to the highest quartile of pulmonary function: 63.9, 50.5, 43.8, and 43.6%, respectively. After adjustment for confounding factors, participants in the first quartile had a significantly increased risk of MCI (ORs, 1.691, 95% CI, 1.267–2.258), with the highest quartile as the reference. In the subgroup analysis, a significant association of pulmonary function and MCI was found in females and those with low physical activity. Meanwhile, we observed an L-shaped relationship between pulmonary function and MCI (Pnon−linear = 0.032).ConclusionsPoor pulmonary function was associated with an increased risk of MCI among rural Chinese adults, and presented a non-linear relationship. These findings remind us of the need for early cognitive assessment in local populations with lower pulmonary function.

Background: Although animal experiments have shown that spermidine (SPD) affects insulin resistance (IR), the evidence for this in humans is still scarce. We aimed to investigate the associations between serum SPD levels and the TyG index in the adult population. Methods: A cross-sectional study was carried out with 4336 participants, all of whom were adults aged 35+ years. The SPD levels in serum were detected using high performance liquid chromatography with a fluorescence detector (HPLC-FLD). The triglyceride-glucose (TyG) index was calculated as Ln [fasting triglycerides (TG) (mg/dL) × fasting glucose (mg/dL)/2]. Results: After multivariable adjustment, including demographic characteristics, behavioral factors associated with heath, and a history of taking medicine, SPD was inversely associated with the TyG index (β = −0.036; SE: 0.009; p < 0.001). Furthermore, each increase of 1 lnSPD significantly decreased the risk of IR with an odds ratio (ORs) (95% confidence intervals (CIs)) of 0.89 (0.83–0.96). Relative to the first quintile, the multivariate-adjusted ORs (95% CIs) for the third and fourth quartile group were 0.80 (0.65, 0.99) and 0.71 (0.57, 0.88), respectively. Conclusions: In conclusion, SPD was inversely associated with the TyG index. Our findings inform future exploratory research on the further mechanism of the association between spermidine and IR.

Objective Accumulation evidence has reported that olfactory impairment may be an essential clinical marker and predictor of mild cognitive impairment or Alzheimer's disease. Method Participants were enrolled in the population‐based, prospective study in Fuxin county, Liaoning province, China between 2019 and 2021. An inverse probability weighting logistic regression and mixed‐effect models were performed to explore the association between dysosmia and cognition and rate of change in cognition, respectively. Besides, we utilized the Robust Rank Aggregation method to integrated three eligible datasets from the Gene Expression Omnibus to identify differential expressed genes. Results A total of 4695 participants were enrolled and 4221 of those were eligible for our cross‐sectional study. The mean (SD) age was 59.93(9.78) years, 64.8% were men. Over a 2‐year follow‐up, of the 2088 participants who completed follow‐up, 1559 participants were eligible for our longitude cohort study. We observed an association between dysosmia and an increased risk of cognitive impairment (OR, 0.47, [95% CI, 0.35–0.64]; p < 0.001). The OR (95% CI) for cognition in females with dysosmia was higher than (OR, 0.73[0.51, 1.05], p = .007) that for males with dysosmia (OR, 0.25[0.15, 0.42], p < 0.001; P for interaction <0.001). Dysosmia was also associated with more rapid decline in calculation ability (p < 0.001). Besides, several DEGs were identified, which are mainly associated with olfactory transduction, detection of chemical stimulus involved in sensory perception of smell, sensory perception of smell, olfactory receptor activity and odorant binding. Interpretation These findings proved novel insight into identifying olfactory dysfunction as potential biomarker for diagnosis of cognitive impairment.