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. 2016 Aug 11;38(1):82–96. doi: 10.1002/hbm.23345

Table 2.

Group and age‐related differences in white matter microstructure

Tract LH/RH WM N Variable ß P adj R2 F p‐F model With TMI correctiona
fMajor FA 90 0.104 4.43 0.006
RD 89 0.108 3.44 0.020
fMinor FA 89 Age −0.354 0.010 0.24 7.94 0.001
Sex −0.317 0.001
MD 89 Group 0.216 0.029 0.17 5.52 0.001
Group × age 0.286 0.045
Sex 0.210 0.035
RD 89 Group 0.192 0.047 0.206 6.72 <0.001
Sex 0.265 0.007
AD 89 Group × age 0.307 0.042 0.071 3.25 0.026
ATR LH FA 95 Group −0.240 0.012 0.182 6.23 <0.001
Sex −0.222 0.021
MD 93 Group 0.259 0.005 0.271 9.55 <0.001 b
Group × age 0.438 0.001 b
RD 93 Group 0.281 0.002 0.283 1.5 <0.001
Group × age 0.413 0.002
RH FA 95 Group −0.213 0.020 0.235 1.62 <0.001
Age −0.273 0.035
MD 95 Group 0.227 0.012 0.269 12.51 <0.001
Group × age 0.390 0.002
RD 95 Group 0.252 0.004 0.330 16.44 <0.001 b
Group × age 0.377 0.002 b
CAB RH AD 80 Group 0.246 0.027 0.066 2.87 0.042
CCG LH FA 95 0.078 3.64 0.016
RD 94 Group 0.21 0.031 0.149 6.44 0.001
RH MD 96 Group 0.242 0.017 0.064 3.15 0.029
RD 96 Group 0.236 0.02 0.063 3.12 0.030
CST LH FA 95 0.081 3.76 0.014
RD 95 0.088 4 0.010
RH FA 95 0.087 3.97 0.010 b
MD 95 Group 0.241 0.016 0.097 4.35 0.007 b
RD 95 Group 0.236 0.015 0.147 6.39 0.001 b
ILF LH FA 95 Age −0.293 0.035 0.155 6.75 <0.001
MD 95 Group 0.201 0.032 0.2 8.85 <0.001 b
Group × age 0.379 0.005
RD 95 0.166 7.17 <0.001 b
AD 95 Group 0.199 0.047 0.069 3.33 0.023
Group × age 0.346 0.018
RH FA 93 Age −0.454 <0.001 0.325 15.77 <0.001
MD 93 Group 0.286 0.002 0.268 12.24 <0.001 b
Group × age 0.311 0.018 b
RD 93 Group 0.233 0.007 0.335 16.42 <0.001 b
Age 0.313 0.013 b
Group × age 0.277 0.027 b
AD 93 Group 0.291 0.004 0.094 4.2 0.008 b
SLFP LH FA 95 Group −0.192 0.048 0.136 5.93 0.001
RD 93 0.082 3.73 0.014
AD 91 Age −0.516 <0.001 0.102 4.42 0.006 b
Group × age 0.363 0.013
RH FA 96 Age −0.296 0.03 0.177 7.8 <0.001 b
MD 96 Group × age 0.394 0.003 0.214 9.61 <0.001
RD 96 0.137 5.88 0.001
SLFT LH FA 96 0.088 4.05 0.009
RD 96 Group 0.261 0.008 0.134 5.9 0.001
RH FA 96 Group −0.197 0.036 0.193 8.56 <0.001 b
Age −0.273 0.043
MD 96 Group 0.233 0.009 0.272 12.85 <0.001
Group × age 0.424 0.001 b
RD 96 Group 0.246 0.005 0.288 13.84 <0.001 b
Group × age 0.379 0.003
AD 96 Group × age 0.388 0.006 0.114 5.06 0.003
UNC LH MD 95 0.153 6.68 <0.001
RD 95 0.122 5.34 0.002
AD 95 0.121 5.33 0.002
RH FA 93 Group −0.344 0.001 0.163 5.49 <0.001
Sex −0.219 0.025
MD 93 Group 0.357 <0.001 0.239 10.61 <0.001 b
RD 93 Group 0.406 <0.001 0.283 10.06 <0.001 b
Sex 0.198 0.029 b
RH AD 94 Group × age 0.297 0.036 0.085 3.89 0.012

Note. Stepwise regression analyses were performed with (TMI as correction variable, then) group, age and group × age interaction, followed by sex as predictors. Numbers in bold reflect significant differences after correcting for multiple comparisons with P < 0.003.

a

Supporting Information Table IV provides the ß‐ and P‐values for the TMI‐corrected results.

b

Results remained significant after taking TMI into account.

Abbreviations: fMajor, Corpus callosum – forceps major; fMinor Corpus callosum – forceps minor; ATR, Anterior thalamic radiation; CAB, Cingulum – angular (infracallosal) bundle; CCG, Cingulum – cingulate gyrus (supracallosal) bundle; CST, Corticospinal tract; ILF, Inferior longitudinal fasciculus; SLFP, Superior longitudinal fasciculus – parietal bundle; SLFT, Superior longitudinal fasciculus – temporal bundle; UNC, Uncinate fasciculus; LH, left hemisphere; RH, right hemisphere; AD, axial diffusivity; FA, fractional anisotropy; MD, mean diffusivity; RD, radial diffusivity.