| BackgroundAdiposity indices,as typical markers to estimate body fat,have been widely used to reflect the nutritional and metabolic status.Currently,adiposity indices are mainly estimated based on different anthropometric measures(e.g.,height,weight,waist circumference,etc.)or levels of blood lipid proteins,thus,might differ in reflecting the amount and distribution of body fat.For example,theoretically,the adiposity indices which take into account both waist circumstance and height in estimation(e.g.,waist-to-height ratio and body roundness index)could more sensitively reflect the accumulation of visceral fat compared to other indices which do not(e.g.,body mass index[BMI]).Therefore,assessing multiple adiposity indices is crucial when investigating the possible health influence of body fat accumulation.The higher level of adiposity index(e.g.,BMI)is associated with brain aging,such as reduced brain volume,accelerated cognitive decline,and even an increased risk of dementia.Cerebral blood flow(CBF)could sensitively reflect the cerebral hemodynamic and metabolic status in old age,and it is an important biomarker in vascular brain aging.Previous study suggested that the higher level of adiposity indices(e.g.,BMI and waist circumstance)was related with reduced CBF in the whole grey matter tissue among older adults.Whereas,the association of other adiposity indices with regional CBF in old age is still unclear in population-based studies.In addition,the insulin resistance levels might indicate the degree of metabolic dysfunction due to higher adiposity indices,so studying the moderating effects of insulin resistance in the association between adiposity index and CBF is also of much significance.ObjectiveIn this population-based cross-sectional study,we aimed to examine the associations of adiposity indices with global and regional cerebral blood flow(CBF)in older adults,while considering insulin resistance.MethodsThe study sample was derived from baseline participants in the ongoing randomized controlled Multimodal INterventions to delay Dementia and disability in rural China(MINDChina)study included in 2018,and MIND-China MRI study in 2019.Finally 103 participants were taken into the current analysis(age≥60 years,female:69.9%).We estimated eight adiposity indices based on anthropometric measures.We automatically quantified global and regional CBF using the arterial spin labeling scans.Insulin resistance was assessed using the triglyceride-glucose index and then dichotomized into high and low levels.Data were analyzed using general linear model and voxel-wise analysis.ResultsAmong all examined adiposity indices,only higher waist-to-height ratio and body roundness index were associated with reduced global CBF(multi-adjusted β-coefficients and 95%CI=-1.76;-3.25,-0.27 and-1.77;-3.25,-0.30,respectively)and hypoperfusion in bilateral middle temporal gyri,angular gyri and superior temporal gyri,left middle cingulum and precuneus(P<0.05);There were statistical interactions of waist-to-height ratio and body roundness index with levels of insulin resistance on CBF,such that the associations of higher waist-to-height ratio and body roundness index with lower global and regional CBF existed only in people with high level of insulin resistance(P<0.05).ConclusionHigher waist-to-height ratio and body roundness index are associated with cerebral hypoperfusion,especially in people with higher level of insulin resistance,which highlights the pathological role of visceral fat in vascular brain aging. |
