Novakova Lenka, Rosenstein Igal, Axelsson Markus, Schoonheim Menno M, Benedict Ralph Hb, Fuchs Tom A
Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Region Västra Götaland, Department of Neurology, Sahlgrenska University Hospital, Gothenburg, Sweden.
Mult Scler. 2025 Aug;31(9):1121-1129. doi: 10.1177/13524585251344794. Epub 2025 May 31.
The Symbol Digit Modalities Test (SDMT) is the most widely used test of cognition in people with multiple sclerosis (PwMS), and repeated testing is confounded by test-retest noise and practice effects.
To investigate the extent to which SDMT practice effects build and plateau with high-frequency testing, reliable cutoffs for longitudinal change, and whether short-interval testing improves detection of cognitive decline.
PwMS were tested with the SDMT monthly across 3 years. Plateau regression analyses were used to determine inflection points of practice effects, and the reliable-change was assessed. To evaluate effects of testing density on cognitive decline detection, this sample was compared with a separate low-density testing group.
The study included 71 people with relapsing-remitting MS (77.5% female), mean (standard deviation (SD)) age 37.3 (9.3), with 27.8 (21.3) SDMT assessments over 3.2 (2.4) years. The plateau of practice effects was reached after 18 repetitions ( < 0.001). Within this sample, ⩾7-point SDMT change was needed to detect cognitive decline with 90% confidence. Higher testing density did not improve detection of cognitive decline ( = 0.256).
We observed practice effects building for eighteen SDMT assessments and test-retest variability consistent with literature. These results provide guidance on SDMT which should be accounted for with alternate versions and reliable-change methodologies.
符号数字模式测验（SDMT）是多发性硬化症患者（PwMS）中使用最广泛的认知测试，重复测试会受到重测噪声和练习效应的干扰。
研究SDMT练习效应在高频测试中形成和稳定的程度、纵向变化的可靠临界值，以及短间隔测试是否能改善对认知衰退的检测。
PwMS在3年时间里每月进行一次SDMT测试。采用平台期回归分析来确定练习效应的拐点，并评估可靠变化。为了评估测试密度对认知衰退检测的影响，将该样本与另一个低密度测试组进行比较。
该研究纳入了71例复发缓解型多发性硬化症患者（77.5%为女性），平均（标准差）年龄37.3（9.3）岁，在3.2（2.4）年中进行了27.8（21.3）次SDMT评估。18次重复后达到练习效应的平台期（<0.001）。在这个样本中，需要SDMT变化≥7分才能以90%的置信度检测到认知衰退。更高的测试密度并没有改善对认知衰退的检测（=0.256）。
我们观察到SDMT评估进行18次时会产生练习效应，且重测变异性与文献一致。这些结果为SDMT提供了指导，应通过替代版本和可靠变化方法加以考虑。
