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Introduction: Population‐based studies have rarely explored the associations of the triglyceride–glucose (TyG) index, a surrogate marker of insulin resistance, with dementia and plasma biomarkers for amyloid beta (Aβ) and neurodegeneration. Methods: This population‐based study included 5199 participants (age ≥ 65 years); of these, plasma Aβ, total tau, and neurofilament light chain (NfL) were measured in 1287 persons. Dementia and subtypes were diagnosed following the international criteria. TyG index was calculated as ln(fasting triglyceride(mg/dL) × fasting glucose[mg/dL]/2). Data were analyzed using logistic and general linear regression models. Results: Dementia, Alzheimer's disease (AD), and vascular dementia (VaD) were diagnosed in 301, 195, and 95 individuals, respectively. A high TyG index was significantly associated with increased likelihoods of dementia and AD; the significant association with dementia remained among participants without cardiovascular disease or diabetes. In the biomarker subsample, a high TyG index was correlated with elevated plasma Aβ, but not with total tau or NfL. Discussion: High TyG index is associated with dementia, possibly via Aβ pathology. [ABSTRACT FROM AUTHOR]

Background and purpose: Little is known about whether nonalcoholic fatty liver disease (NAFLD) is associated with dementia or the role of serum proinflammatory cytokines in the association. We aimed to investigate the interrelationships of NAFLD, serum cytokines, and dementia among rural‐dwelling older adults. Methods: This population‐based cross‐sectional study included 5129 participants (aged ≥60 years; 61.79% women) who were living in rural communities and examined in March 2018–September 2018. NAFLD was defined through transabdominal ultrasound examination in the absence of hepatitis B or excessive alcohol consumption. Serum cytokines were measured in a subsample (n = 1686). Dementia, Alzheimer disease (AD), and vascular dementia (VaD) were diagnosed following international criteria. Data were analyzed with logistic regression and mediation models. Results: Of the 5129 participants, 455 (8.87%) were detected with moderate‐to‐severe NAFLD, and 292 (5.69%) were diagnosed with dementia (188 with AD and 96 with VaD). The multivariable adjusted odds ratios associated with moderate‐to‐severe (vs. no‐to‐mild) NAFLD were 2.22 (95% confidence interval [CI] = 1.41–3.49) for all‐cause dementia, 1.88 (95% CI = 1.01–3.50) for AD, and 2.62 (95% CI = 1.33–5.17) for VaD. In the cytokine subsample, controlling for multiple potential confounders, moderate‐to‐severe NAFLD was significantly associated with higher levels of serum monocyte chemotactic protein‐1, interleukin‐17A, interleukin‐6 (IL‐6), interleukin‐8, and tumor necrosis factor‐α (P < 0.05). The mediation analysis showed that IL‐6 mediated 12.56% of the association between NAFLD and VaD. Conclusions: Moderate‐to‐severe nonalcoholic fatty liver disease is associated with dementia and AD, especially with VaD, among rural‐dwelling Chinese older adults, in which the association with VaD is partly mediated by serum inflammatory cytokines. [ABSTRACT FROM AUTHOR]

Background and purpose: Current evidence supports the involvement of lipids in brain aging. A range of serum lipids is explored in association with brain structure and cognitive function amongst rural‐dwelling older adults. Methods: This population‐based cross‐sectional study included 184 rural‐dwelling adults (age ≥ 65 years, 39.1% women) in Shandong, China. In 2014–2016, data on demographics, lifestyle, health conditions and serum lipids were collected. Volumes of gray matter, white matter, ventricles, hippocampus and white matter hyperintensity were automatically estimated on brain magnetic resonance imaging. Global cognitive function was assessed with the Mini‐Mental State Examination (MMSE), and mild cognitive impairment (MCI) was defined according to Petersen's criteria. Data were analyzed using the general linear regression, logistic regression and mediation models. Results: Of the 184 participants, 47 were defined with MCI. Low high‐density lipoprotein cholesterol (HDL‐C; <1.55 vs. ≥1.55 mmol/l) was significantly associated with reduced volumes of total white matter (multi‐adjusted β = −9.77, 95% confidence interval −19.48–0.06) and hippocampus (−0.23, −0.46–0.01), a lower MMSE score (−1.49, −2.67–0.31) and a higher likelihood of MCI (multi‐adjusted odds ratio 3.21, 95% confidence interval 1.42–7.29). The mediation effects of structural brain measures on the associations between a low level of HDL‐C and MMSE score or MCI were not statistically significant (p > 0.05). Conclusions: This study suggests that low HDL‐C may be involved in structural brain aging and cognitive dysfunction amongst rural‐dwelling older adults in China, but the association of low HDL‐C with cognitive aging phenotypes appears not to be mediated by brain structure. [ABSTRACT FROM AUTHOR]