. Author manuscript; available in PMC: 2013 Mar 1.

Published in final edited form as: Biochim Biophys Acta. 2011 Aug 16;1822(3):386–400. doi: 10.1016/j.bbadis.2011.08.003

Table 1.

Patterns of adult age differences in white matter diffusivity properties

Anatomical location	Pattern for older adults, relative to younger adults	Biological interpretation
Genu of the corpus callosum	FA ↓ RD↑ AD↑ (MD↑)^*	Loss/disruption of both axons and myelin
Body of the corpus callosum	(FA ↓ RD↑ AD↑ MD↑)^*
External capsule	FA ↓ RD↑ AD↑ (MD↑)^*
Anterior dorsal cingulum	(FA ↓ RD↑ AD↑ MD↑)^*

Fornix	FA ↓ RD↑ AD↑ (MD↑)^*	Loss/disruption of both axons and myelin; partial volume with CSF

Anterior limb of internal capsule	(FA↓ RD↑ MD↑)^*	Predominant myelin disruption or loss
Middle frontal gyrus (SLF)	FA ↓ RD↑ (AD↑ MD↑)^*
WM of the straight gyrus	FA↓ RD↑
Forceps major	FA↓ RD↑
Sagittal stratum	FA↓ RD↑ (MD↑)^*
Posterior dorsal cingulum	(FA ↓ RD↑)^*

Superior corona radiata	FA↓ RD↑ AD↓	Fiber loss with glial infiltration
Forceps minor	FA↓ RD↑ AD↓
Retrolenticular internal capsule	FA↓ RD↑ AD↓
Parahippocampal WM	FA↓ RD↑ (AD↓)^*

Posterior limb of internal capsule	(FA↓ AD↓ MD↓)^*	Gliosis or early axonal injury/Less coherent tract organization
Cerebral peduncles	FA↓ AD↓

Note. The patterns of age differences (second column) are expressed as the direction of significant diffusivity effects, for older adults, relative to younger adults, reported by Bennett et al. [51] and Burzynska et al. [53]. FA = fractional anisotropy; AD = axial diffusivity; RD = radial diffusivity; MD = mean diffusivity; CSF = cerebrospinal fluid; SLF = superior longitudinal fasciculus; WM = white matter; ↓ = decrease; ↑ = increase.

These effects (within parentheses) were specific to Burzynska et al. [53]. The remaining effects were common to both Bennett et al. (2010) and Burzynska et al. [53]. None of the effects was specific to Bennett et al. [51].