BACKGROUND Dementia is common in Parkinson's disease (PD) but measures that track cognitive change in PD are lacking. Brain tissue iron accumulates with age and co-localises with pathological proteins linked to PD dementia such as amyloid. We used quantitative susceptibility mapping (QSM) to detect changes related to cognitive change in PD. METHODS We assessed 100 patients with early-stage to mid-stage PD, and 37 age-matched controls using the Montreal Cognitive Assessment (MoCA), a validated clinical algorithm for risk of cognitive decline in PD, measures of visuoperceptual function and the Movement Disorders Society Unified Parkinson's Disease Rating Scale part 3 (UPDRS-III). We investigated the association between these measures and QSM, an MRI technique sensitive to brain tissue iron content. RESULTS We found QSM increases (consistent with higher brain tissue iron content) in PD compared with controls in prefrontal cortex and putamen (p<0.05 corrected for multiple comparisons). Whole brain regression analyses within the PD group identified QSM increases covarying: (1) with lower MoCA scores in the hippocampus and thalamus, (2) with poorer visual function and with higher dementia risk scores in parietal, frontal and medial occipital cortices, (3) with higher UPDRS-III scores in the putamen (all p<0.05 corrected for multiple comparisons). In contrast, atrophy, measured using voxel-based morphometry, showed no differences between groups, or in association with clinical measures. CONCLUSIONS Brain tissue iron, measured using QSM, can track cognitive involvement in PD. This may be useful to detect signs of early cognitive change to stratify groups for clinical trials and monitor disease progression.

中文翻译：

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脑铁沉积与帕金森病的认知严重程度有关。

背景 痴呆在帕金森病 (PD) 中很常见，但缺乏追踪 PD 认知变化的措施。脑组织铁随着年龄的增长而积累，并与与 PD 痴呆相关的病理蛋白（如淀粉样蛋白）共定位。我们使用定量磁化率图 (QSM) 来检测与 PD 认知变化相关的变化。方社会统一帕金森病评定量表第 3 部分 (UPDRS-III)。我们调查了这些措施与 QSM 之间的关联，QSM 是一种对脑组织铁含量敏感的 MRI 技术。结果 我们发现与对照组相比，PD 患者的前额皮质和壳核 QSM 增加（与较高的脑组织铁含量一致）（针对多重比较校正的 p <0.05）。PD 组的全脑回归分析确定 QSM 增加协变：(1) 海马体和丘脑的 MoCA 评分较低，(2) 视觉功能较差，顶叶、额叶和内侧枕叶皮质的痴呆风险评分较高，(3 ) 在壳核中具有更高的 UPDRS-III 分数（所有 p < 0.05 已针对多重比较进行校正）。相比之下，使用基于体素的形态测量法测量的萎缩在组间或与临床测量相关时没有差异。结论 使用 QSM 测量的脑组织铁可以追踪 PD 中的认知参与。