Hugenschmidt Christina E, Peiffer Ann M, Kraft Robert A, Casanova Ramon, Deibler Andrew R, Burdette Jonathan H, Maldjian Joseph A, Laurienti Paul J
Neuroscience Program, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
Cereb Cortex. 2008 Feb;18(2):433-42. doi: 10.1093/cercor/bhm080. Epub 2007 Jun 16.
Age-related alterations in white matter have the potential to profoundly affect cognitive functioning. In fact, magnetic resonance imaging (MRI) studies using fractional anisotropy (FA) to measure white matter integrity reveal a positive correlation between FA and behavioral performance in older adults. Confounding these results are imaging studies demonstrating age-related white matter atrophy in some areas displaying altered FA, suggesting changes in diffusion may be simply an epiphenomenon of tissue loss. In the current study, structural MRI techniques were used to identify the relationship between white matter integrity and decreased volume in healthy aging adults. The data demonstrated that white matter atrophy did in fact account for differences in some areas, but significant FA decreases remained across much of the white matter after adjusting for atrophy. Results suggest a complex relationship between changes in white matter integrity and volume. FA appears to be more sensitive than volume loss to changes in normal appearing tissue, and these FA changes may actually precede white matter atrophy in some brain areas. As such, the ability to detect early white matter alterations may facilitate development of targeted treatments that prevent or slow age-related white matter degradation and associated cognitive sequelae.
与年龄相关的白质变化有可能深刻影响认知功能。事实上，使用分数各向异性（FA）来测量白质完整性的磁共振成像（MRI）研究表明，老年人的FA与行为表现之间存在正相关。使这些结果变得复杂的是，成像研究显示在一些FA发生改变的区域存在与年龄相关的白质萎缩，这表明扩散变化可能仅仅是组织损失的一种附带现象。在当前的研究中，采用结构MRI技术来确定健康老龄成年人白质完整性与体积减小之间的关系。数据表明，白质萎缩实际上确实在某些区域造成了差异，但在调整萎缩因素后，大部分白质区域的FA仍显著下降。结果表明白质完整性变化与体积之间存在复杂的关系。FA似乎比体积损失对正常外观组织的变化更敏感，并且这些FA变化在某些脑区可能实际上先于白质萎缩出现。因此，检测早期白质改变的能力可能有助于开发针对性的治疗方法，以预防或减缓与年龄相关的白质退化及相关的认知后遗症。
