Research On Influencing Factors Of Brainstem Volume In Community Population

OBJECTIVE:To investigate 1)Are risk factors for vascular disease and risk factors for brain atrophy associated with decreased volume of brain sub-structures?2)Is cerebral small vessel disease burden related to decrease in the volume of each sub-structure of the brainstem?3)Is the effect of risk factors on the volume of each sub-structure of the brainstem independent of their effect on global brain atrophy?4)Is the midbrain volume associated with deterioration of cognition and motor function?METHODS:This study was a cross-sectional association study in a community-based population.Structured survey forms were used to collect demographic data,body measurements,and medical history data,and blood samples were taken to analyze serological biomarkers.Brain images were collected by 3T MRI,and the cerebral small vessel disease marker burden was analyzed by manual reading.The volumes of brainstem sub-structures(midbrain volume,pons volume and medulla volume)and other brain structure volumes were determined by automatic segmentation and quantification.Electronic cognitive and motor testing tools were used to assess cognitive and motor function.General linear regression models were used to analyze the association between risk factors,small vessel disease burden and brain sub-structure volume,adjusting for the confounding factors.The determinants of brainstem sub-structure volume were explored by using the method of stepwise inclusion of variables in the general linear model.The general linear regression model was used to analyze the association between midbrain volume fraction and cognitive and motor f:unction parameters.RESULTS:1)Vascular risk factors were related to the volumetric variation of the brainstem substructures,and the structure of risk factors affecting each substructure was different.Advanced age was a risk factor for loss of the midbrain volume and medulla volume.Elevated HAblc level was a risk factor for midbrain volume,pons volume,and medulla volume reduction.2)In terms of morkers for cerebral small vessel disease,brain parenchymal fraction was significantly associated with the size of all the brainstem sub-structures.There was a significant association between white matter signal volume and pons volume/medulla volume which tolerated adjustment of vascular risk factors.Cerebral small vessel disease scores,reflecting a global burden of CSVD,was not associated with brainstem sub-structure volumes.3)In the multivariate linear regression models with stepwise inclusion of variables based on a priori hypothesis,further adding brain parenchymal fraction into the model together with total intracranial volume,age,and gender could additionally lead to a 2.46%increase in the estimated explained variation of midbrain volume,2.17%increase in that of pons volume,and 0.79%increase in that of medulla volume.Risk factors of cerebrovasculair disease and brain atrophy,and thereafter CSVD markers were further included in the models.In the final model,the partial regression coefficient of HbAlc remained significant,while that of CSVD markers were not.4)In the univariate analysis,there was a significant correlation between the midbrain volume and the cognitive measures and time for finger tap,which was an index for upper limb motor coordination,but the statistical significance disappeared after adjusting for the relevant confounding factors.Conclusion:In this sample of community-dwelling middle-aged and older people,midbrain volume was related to age,while pons volume was related to the volume of white matter hyperintensities.Elevated glycosylated hemoglobin level was a risk factor for decreased volume of all three brainstem sub-structures.