Article Figures & Data
Figures
- Figure 1.
Example of callosal subregion ROI tracts registered to a subject’s native b0 image. Color represents each callosal subregion tract fiber.
- Figure 2.
Effects of age on regional tract FA across the corpus callosum segments.
- Figure 3.
Effects of age on regional tract RD across corpus callosum segments.
- Figure 4.
Effects of age on regional tract AD across corpus callosum segments.
- Figure 5.
Circular barplot depicting an anteroposterior gradient of vulnerability to age across CC subregion tracts. Bar heights indicate the age–diffusion correlation for each metric, in each CC segment. Significant differences in age–diffusion associations were tested using Steiger’s Z tests. These associations differed significantly for FA between the genu and splenium, the genu and isthmus, the anterior midbody and splenium, the anterior midbody and isthmus, the posterior midbody and splenium (Steiger’s Z p < 0.001), and the posterior midbody and isthmus (p < 0.05). A similar stepwise pattern was found for RD: between the genu and isthmus, genu and splenium, anterior midbody and isthmus, anterior midbody and splenium, posterior midbody and splenium (p’s < 0.001), genu and posterior midbody, and isthmus and splenium (p’s < 0.05). Although weaker, this pattern exists for AD: between the genu and the splenium, the genu and the posterior midbody, the anterior midbody and splenium (p’s < 0.001), between the genu and isthmus, anterior midbody and isthmus, and anterior midbody and splenium (p’s < 0.05).
- Figure 6.
A significant association between pulse pressure and radial diffusivity, controlling for age. Radial diffusivity across the corpus callosum segments combined increases as a function of increasing pulse pressure, beyond the effects of age on RD.
- Figure 7.
Age–pulse pressure interaction on CC axial diffusivity. A, Simple slope plots illustrating the effects of pulse pressure on AD are dependent on age, with significance in middle-aged and older adults, where increasing pulse pressure is associated with increased axial diffusivity in the corpus callosum. B, Johnson–Neyman interval plot suggests that the significance range of the interaction begins at approximately the age of 60 years.
Tables
Demographic characteristics Number of participants 174 Age, mean ± SD 53.56 ± 18.90 Sex N (Male/Female) 72/102 Years of education, mean ± SD 15.50 ± 2.50 MMSE, mean ± SD 29.02 ± 0.85 CESD, mean ± SD 4.32 ± 3.79 BMI, mean ± SD 27.30 ± 5.13 Smokers, N (%) 7 (4.07%) High cholesterol, N (%) 36 (20.93%) Hypertensives, N (%) 38 (21.84%) Systolic BP, mean ± SD 126.37 ± 16.54 Diastolic BP, mean ± SD 75.26 ± 9.54 Heart rate, mean ± SD 68.43 ± 9.84 Pulse pressure, mean ± SD 51.11 ± 12.06 Mean arterial BP, mean ± SD 92.29 ± 10.93 MMSE, Mini-Mental Status Exam; CESD, Center for Epidemiological Studies Depression Scale; BMI, body mass index; BP, blood pressure.
Metric Predictor df, dferror SS F p FA Between subjects Age 1, 171 0.347 77.867 <0.001*** Within subjects Subregion 4, 684 1.395 476.799 <0.001*** Subregion x age 4, 684 0.046 15.577 <0.001*** RD Between subjects Age 1, 171 1.123 105.901 <0.001*** Within subjects Subregion 4, 684 2.217 395.324 <0.001*** Subregion x age 4, 684 0.129 22.963 <0.001*** AD Between subjects Age 1, 171 0.215 10.239 0.002** Within subjects Subregion 4, 684 1.970 159.027 <0.001*** Subregion x age 4, 684 0.072 5.818 <0.001*** df, degrees of freedom; SS, sum of squares; FA, fractional anisotropy; RD, radial diffusivity; AD, axial diffusivity.
*p < 0.05, **p < 0.01, ***p < 0.001.
Segment FA RD AD Mean ± SD r Mean ± SD r Mean ± SD r Genu 0.63 ± 0.04 −0.628** 0.49 ± 0.06 0.694** 1.56 ± 0.07 0.387** Anterior Midbody 0.63 ± 0.04 −0.612** 0.50 ± 0.07 0.677** 1.60 ± 0.07 0.359** Posterior Midbody 0.65 ± 0.05 −0.515** 0.48 ± 0.07 0.561** 1.64 ± 0.09 0.136 Isthmus 0.63 ± 0.06 −0.327** 0.52 ± 0.09 0.405** 1.69 ± 0.09 0.150* Splenium 0.73 ± 0.03 −0.232** 0.38 ± 0.04 0.336** 1.67 ± 0.10 0.023 Pearson’s correlations, *p < 0.05, **p < 0.01.
Metric Predictor df, dferror SS F p FA Between subjects Age 1, 170 0.161 36.246 <0.001*** Pulse pressure 1, 170 0.007 1.552 0.215 Within subjects Subregion 4, 680 1.395 477.463 <0.001*** Subregion x age 4, 680 0.024 8.312 <0.001*** Subregion x pulse pressure 4, 680 0.004 1.225 0.299 RD Between subjects Age 1, 170 0.450 43.503 <0.001*** Pulse pressure 1, 170 0.052 5.049 0.026* Within subjects Subregion 4, 680 2.217 395.128 <0.001*** Subregion x age 4, 680 0.066 11.761 <0.001*** Subregion x pulse pressure 4, 680 0.005 0.893 0.433 AD Between subjects Age 1, 169 0.039 1.990 0.160 Pulse pressure 1, 169 0.020 1.044 0.308 Age x pulse pressure 1, 169 0.187 9.662 0.002* Within subjects Subregion 4, 676 1.299 104.052 <0.001*** Subregion x age 4, 676 0.026 2.076 0.082 Subregion x pulse pressure 4, 676 0.006 0.506 0.672 Subregion x age x pulse pressure 4, 676 0.001 0.072 0.991 df, degrees of freedom; SS, sum of squares; FA, fractional anisotropy; RD, radial diffusivity; AD, axial diffusivity.
↵* p < 0.05, **p < 0.01, ***p < 0.001.
Metric Predictor df, dferror SS F p FA Between subjects Age 1, 170 0.223 50.505 <0.001*** Hypertension status 1, 170 0.010 2.150 0.144 Within subjects Subregion 4, 680 0.739 253.190 <0.001*** Subregion–age 4, 680 0.026 9.074 <0.001*** Subregion–hypertension status 4, 680 0.004 1.328 0.258 RD Between subjects Age 1, 170 0.724 69.037 <0.001*** Hypertension status 1, 170 0.031 2.919 0.089 Within subjects Subregion 4, 680 1.162 207.338 <0.001*** Subregion–age 4, 680 0.083 14.868 <0.001*** Subregion–hypertension status 4, 680 0.007 1.171 0.318 AD Between subjects Age 1, 170 0.104 4.977 0.027* Hypertension status 1, 170 0.033 1.572 0.212 Within subjects Subregion 4, 680 1.053 84.801 <0.001*** Subregion–age 4, 680 0.068 5.506 0.001** Subregion–hypertension status 4, 680 0.008 0.658 0.621 df, degrees of freedom; SS, sum of squares; FA, fractional anisotropy; RD, radial diffusivity; AD, axial diffusivity.
↵* p < 0.05, **p < 0.01, ***p < 0.001.
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