Lopez Francesca V, Rohl Brittany Y, Wagle-Shukla Aparna, Bowers Dawn
Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USA.
Department of Neurology and Fixel Center for Neurological Diseases, University of Florida, Gainesville, FL, USA.
Clin Park Relat Disord. 2019;1:77-81. doi: 10.1016/j.prdoa.2019.09.002. Epub 2019 Oct 17.
Depletion of dopamine is a major neuropathological feature of Parkinson's disease; however, 15% of patients with parkinsonian motor symptoms have neuroimaging evidence of intact dopaminergic function. Recent work has demonstrated that such patients without dopaminergic deficit are at a greater risk of cognitive impairment yet have intact olfaction relative to parkinsonian patients with dopaminergic deficit.
Given the high discriminatory power of olfaction assessments in movement disorders, the current study sought to determine whether olfaction dysfunction differentially predicted cognitive decline in patients with or without dopaminergic deficit.
Data were obtained from the Parkinson's Progression Marker Initiative. The total sample included 401 patients with and 51 patients without dopaminergic deficit, based on neuroimaging scans, and 175 healthy controls. Participants were categorized into non-impaired or impaired olfaction groups based on performance on the University of Pennsylvania Smell Identification Test. Participants were administered the Montreal Cognitive Assessment twice (baseline and two-year follow-up), and change scores were calculated to examine changes in cognition over time.
Within the impaired olfaction groups, participants without dopaminergic deficit had lower cognitive scores than participants with dopaminergic deficit and healthy controls at baseline. Group differences were not significant at follow-up; rather, impaired baseline olfaction predicted cognitive decline across all study participants.
Future studies are needed to assess whether the profile of motor and non-motor symptoms in patients without dopaminergic deficit, including olfaction, are deserving of their own syndrome, or whether individual patients may fit better under alternative, existing diagnoses.
多巴胺耗竭是帕金森病的主要神经病理学特征；然而，15%有帕金森运动症状的患者神经影像学证据显示多巴胺能功能完好。最近的研究表明，相对于多巴胺能功能缺陷的帕金森病患者，这些没有多巴胺能缺陷的患者认知障碍风险更高，但嗅觉功能完好。
鉴于嗅觉评估在运动障碍中具有较高的鉴别能力，本研究旨在确定嗅觉功能障碍是否能不同程度地预测有无多巴胺能缺陷患者的认知衰退。
数据来自帕金森病进展标志物计划。根据神经影像学扫描结果，总样本包括401例有多巴胺能缺陷的患者、51例无多巴胺能缺陷的患者以及175名健康对照者。根据宾夕法尼亚大学嗅觉识别测试的表现，将参与者分为嗅觉未受损组或受损组。对参与者进行两次蒙特利尔认知评估（基线和两年随访），并计算变化分数以检查认知随时间的变化。
在嗅觉受损组中，无多巴胺能缺陷的参与者在基线时的认知得分低于有多巴胺能缺陷的参与者和健康对照者。随访时组间差异不显著；相反，基线嗅觉受损可预测所有研究参与者的认知衰退。
未来需要开展研究，以评估无多巴胺能缺陷患者（包括嗅觉方面）的运动和非运动症状特征是否应被视为一种独立的综合征，或者个体患者是否更符合其他现有的诊断。
