Das Tanusree, Kim Nessa, McDaniel Colin, Poston Kathleen L
Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA.
Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA.
Clin Park Relat Disord. 2020 Jun 3;3:100062. doi: 10.1016/j.prdoa.2020.100062. eCollection 2020.
Parkinson's disease (PD) patients commonly experience episodic memory impairments, which are associated with an increased risk of dementia. The Mnemonic Similarity Task (MST) is a well-validated test to investigate episodic memory changes in healthy aging and in neurodegenerative diseases but has not been studied in PD patients.
In the MST task, participants respond during a testing phase whether visualized images are "repeat", "similar", or "new", compared to images previously shown during an encoding phase. We tested 17 PD without cognitive impairment (level-II criteria), both off (PD-OFF) and on (PD-ON) dopaminergic medications; and compared PD-OFF with 17 age- and education-matched healthy controls (HC).
We found no influence of dopaminergic medications nor of disease on MST reaction time for any responses ("repeat", "similar", and "new") during the test phase. However, response probabilities showed that the MST is sensitive to subtle PD-related memory impairments. Specifically, PD-OFF responded more frequently with 'repeat', instead of 'similar' during lure trials, compared to HC ( = 0.030). This finding was still significant after correcting for response bias using the Recognition Index ( = 0.005).
PD patients perform the MST without interference from bradykinesia or other PD-related motor symptoms. Our findings suggest that PD patients who do not meet criteria for mild cognitive impairment can have subtle recall or recognition impairments, which can be identified using the MST. We propose the MST as a well-tolerated and sensitive cognitive task in future studies of episodic memory impairment and progressive memory dysfunction in people with PD.
帕金森病（PD）患者常出现情景记忆障碍，这与痴呆风险增加有关。记忆相似性任务（MST）是一项经过充分验证的测试，用于研究健康衰老和神经退行性疾病中的情景记忆变化，但尚未在PD患者中进行研究。
在MST任务中，参与者在测试阶段对可视化图像与编码阶段之前显示的图像相比是“重复”、“相似”还是“新的”做出反应。我们测试了17名无认知障碍（II级标准）的PD患者，分别处于多巴胺能药物停药期（PD - OFF）和服药期（PD - ON）；并将PD - OFF组与17名年龄和教育程度匹配的健康对照（HC）进行比较。
我们发现，在测试阶段，多巴胺能药物和疾病对任何反应（“重复”、“相似”和“新的”）的MST反应时间均无影响。然而，反应概率表明MST对与PD相关的细微记忆障碍敏感。具体而言，与HC相比，PD - OFF组在诱饵试验中更频繁地回答“重复”而非“相似”（ = 0.030）。使用识别指数校正反应偏差后，这一发现仍然显著（ = 0.005）。
PD患者在执行MST时不受运动迟缓或其他与PD相关的运动症状的干扰。我们的研究结果表明，不符合轻度认知障碍标准的PD患者可能存在细微的回忆或识别障碍，这可以通过MST识别出来。我们建议在未来关于PD患者情景记忆障碍和进行性记忆功能障碍的研究中，将MST作为一种耐受性良好且敏感的认知任务。
