Objectives

To test the hypotheses that peak skeletonized mean diffusivity (PSMD), a measure of cerebral white matter microstructural disruption, is 1) increased in patients with cerebral amyloid angiopathy (CAA) compared to normal control (NC), mild cognitive impairment (MCI), and Alzheimer’s disease (AD); 2) associated with neuropsychological test performance among CAA patients; and 3) increased more quickly over one year in CAA than in AD, MCI, and NC.

Methods

Ninety-two participants provided a medical history, completed a neuropsychological assessment, and had a magnetic resonance (MR) exam including diffusion tensor imaging (DTI) from which PSMD was calculated. A 75-minute neuropsychological test battery was used to derive domain scores for memory, executive function, and processing speed. Multivariable analyses controlling for age and sex (and education, for cognitive outcomes) were used to test the study hypotheses.

Results

PSMD was higher in the CAA group (mean 4.97 × 10⁻⁴ mm²/s) compared to NC (3.25 × 10⁻⁴ mm²/s), MCI (3.62 × 10⁻⁴ mm²/s) and AD (3.89 × 10⁻⁴ mm²/s) groups (p < .01). Among CAA patients, higher PSMD was associated with slower processing speed (estimated −0.22 standard deviation (SD) change in processing speed z score per SD increase in PSMD, 95% CI −0.42 to −0.03, p = .03), higher WMH volume [β = 0.74, CI 0.48 to 1.00], and higher CAA SVD score [β = 0.68, CI 0.24 to 1.21] but was not associated with MMSE, executive function, memory, CMB count, or cortical thickness. PSMD increased over 1-year in all groups (p < .01) but without rate differences between groups (p = .66).

Conclusions

PSMD, a simple marker of diffuse global white matter heterogeneity, is increased in CAA. Our findings further support a role for white matter disruption in causing cognitive impairment in CAA.

中文翻译：

---

峰状骨架白质的横截面和纵向差异意味着脑淀粉样血管病的扩散性。

目标

为了验证以下假设：脑淀粉样血管病（CAA）患者与正常对照组（NC），轻度认知障碍（MCI）相比，峰值骨架平均弥散度（PSMD）是衡量大脑白质微结构破坏的一种指标，其增加了：和阿尔茨海默氏病（AD）；2）与CAA患者的神经心理测试表现有关；3）CAA在一年多的时间内比在AD，MCI和NC中的增长更快。

方法

92名参与者提供了病史，完成了神经心理学评估，并进行了包括弥散张量成像（DTI）在内的磁共振（MR）检查，由此计算出PSMD。75分钟的神经心理测试电池用于得出记忆力，执行功能和处理速度的领域分数。控制年龄和性别（以及教育，认知成果）的多变量分析用于检验研究假设。

结果

与NC（3.25×10 ^-4  mm ² / s），MCI（3.62×10 ^-4  mm ² / s）和AD（3.89 ）相比，CAA组的PSMD（平均4.97×10 ^-4  mm ² / s）高。×10 ^-4  mm ² / s）组（p  <.01）。在CAA患者中，较高的PSMD与较慢的处理速度相关（估计PSMD每SD增加的处理速度z得分估计为-0.22标准偏差（SD）变化，95％CI -0.42至-0.03，p  = .03），WMH较高体积[ β  = 0.74，CI为0.48至1.00]，以及更高的CAA SVD评分[ β = 0.68，CI为0.24至1.21]，但与MMSE，执行功能，记忆力，CMB计数或皮层厚度无关。所有组的PSMD均增加了1年以上（p  <.01），但各组之间的比率无差异（p  = .66）。

结论

PSMD是弥漫性全球白质异质性的简单标志，在CAA中有所增加。我们的发现进一步支持白质破坏在引起CAA认知障碍中的作用。