| Objective: To research the whole white matter volume change of normaladult brain in healthy aging, and to evaluate the correlation between whitematter volume and age, gender in vivo by VBM.Methods: One hundred and eighty-seven volunteers, recruited fromAugust2013to November2013, were examined by MRI and T1-FFEsequence. There were92male cases and95cases of female, age range20to78years old (average age47.2，median age47years old). According to ageand gender, all the participants can be divided into young, middle-aged andold group. The T1-FEE sequence was pre-processed by the VBM(Voxel-based morphometry). The white matter were obtained after segmentand smooth, and then perform the statistical analysis. The t test was used tocompare data obtained from male and female cases. The difference betweenage groups were analyzed by ANOVA. Using regression analysis to detect thewhole brain white matter volume age-related change, and then ROIs.Statistical significance was designated at P<0.05.Results:1Analysis of gender differences in whole brain volume: Adjusted totalintracranial volume, women have a greater volume of white matter than man(t=3.79, P=0.0001, FDR corrected). Women showed more white matter inmedulla, pons, bilateral cerebral peduncle, bilateral medial temporal lobe,bilateral cerebellum anterior lobe, left occipital lobe, superior bilateral frontalgyrus, the left frontal orbital gyrus, bilateral parietal lobe and genu of corpuscallosum. Men showed more white matter volume mainly in bilateral posteriorinferior cerebellum, bilateral external capsule, bilateral rectal gyrus, and someregions in the left occipital lobe, bilateral parietal lobe.2Analysis of white matter volume changes between different age groups: Weused two-factor variance analysis between young, middle-aged and old group. There were significant main effect of age between every two groups (P<0.05,FDR corrected). Compared with the middle-aged group of young group, whitematter volume showed an increase in brain regions located in the bilateralfrontal gyrus, precentral gyrus, corona radiate, anterior limb of the internalcapsule, the right external capsule, right middle cerebral peduncle, rightoccipital lobe. When compared old group with young group, obvious atrophyof brain regions were located in bilateral frontal lobes, bilateral cerebralpeduncle, bilateral posterior limb of the internal capsule, anterior limb of theleft internal capsule, splenium of corpus callosum, bilateral occipital lobe, lefttemporal lobe, anterior cingulated gyrus. Compared old group withmiddle-aged group, obvious atrophy of brain regions located in bilateralmedial temporal lobe, inferior temporal gyrus, the left superior temporal gyrus,bilateral cerebral peduncle, thalamus, bilateral middle frontal gyrus, leftinferior frontal gyrus, bilateral coronal radiation, the body and genu of thecorpus callosum, bilateral cingulate gyrus, left parietal lobe, bilateralparahippocampal gyrus, right precuneus and some cerebellum areas. Whenwithout multiple contrast correction, main effect of sex could be observedbetween the young and middle-aged group in the bilateral cerebellum, ventralof pons, medulla, left corona radiata, left occipital lobe. They also existbetween young and old group’s comparison, main located bilateral coronaradiata, bilateral hippocampus, left external capsule, left posterior limb ofinternal capsule. While women show larger volume in these regions. We foundno significant interaction effect age by gender (P<0.05, FDR corrected) eachin the two groups.3Analysis of the correlation between white matter volume and age：Wholewhite matter volume and age is nonlinear, quadratic model, just like inverted"U" shape (R2=0.124, P<0.000). The ROI of white matter volume as theregression analysis showed an extensive and different modes nonlinearcorrelation, particularly in the frontal(R2=0.13，P<0.001). The time age-relatedatrophy of the occipital lobe appears at the latest. Bilateral cerebellum,midbrain, pons and medulla showed no significant correlation. Conclusion:1There are sex differences in white matter volume after adjusting totalcerebral volume. Women show greater white matter volume than men in theprocess of aging, such as in bilateral corona radiata, bilateral parahippocampalgyrus, left occipital lobe, left cerebral peduncle and left internal capsule.Women had a protective effect in these regions.2In the course of normal aging, the whole white matter volume and age showquadratic model, just like inverted "U" type, reaches its maximum at about50years old, and then gradually decreased. However, different brain regions existdifferent shrink model. Generally regions follow the anterior-posteriorgradient. Frontal lobe show the strongest age-related, while the occipitalemerge age-related changes late.3Bilateral cerebellar hemisphere, midbrain, pons and medulla did not showsignificant age-related. |
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