Visuospatial impairment in Parkinson’s disease (PD) heralds the onset of a progressive dementia syndrome and might be associated with cholinergic dysfunction. It remains unclear however, whether degeneration of the cholinergic basal forebrain is directly related to cognitive decline, or whether relationships between this region and cognitive function are mediated by closely related brain structures such as those in the medial temporal lobe. To evaluate relationships between structure of the cholinergic basal forebrain, medial temporal lobe and cognition, 27 PD patients without dementia and 20 controls underwent neuropsychological assessment and MRI. Volumes of the cholinergic basal forebrain nuclei, the entorhinal cortex, the hippocampus and its subfields were measured. Regression models utilised basal forebrain and hippocampal volumetric measures to predict cognitive performance. In PD, visuospatial memory (but not verbal memory or executive function) was correlated with hippocampal volume, particularly CA2-3, and basal forebrain subregion Ch1-2, but not Ch4. In addition, hippocampal volume was correlated with Ch1-2 in PD. The relationship between Ch1-2 and visuospatial memory was mediated by CA2-3 integrity. There were no correlations between cognitive and volumetric measures in controls. Our data imply that the integrity of the cholinergic basal forebrain is associated with subregional hippocampal volume. Additionally, a relationship between visuospatial function and cholinergic nuclei does exist, but is fully mediated by variations in hippocampal structure. These findings are consistent with the recent hypothesis that forebrain cholinergic system degeneration results in cognitive deficits via cholinergic denervation, and subsequent structural degeneration, of its target regions.

帕金森病 (PD) 的视觉空间障碍预示着进行性痴呆综合征的发作，并可能与胆碱能功能障碍有关。然而，尚不清楚胆碱能基底前脑的退化是否与认知能力下降直接相关，或者该区域与认知功能之间的关系是否由密切相关的大脑结构（例如内侧颞叶中的大脑结构）介导。为了评估胆碱能基底前脑结构、内侧颞叶和认知之间的关系，27 名无痴呆的 PD 患者和 20 名对照组接受了神经心理学评估和 MRI。测量胆碱能基底前脑核、内嗅皮质、海马及其亚区的体积。回归模型利用基底前脑和海马体积测量来预测认知表现。在 PD 中，视觉空间记忆（但不是语言记忆或执行功能）与海马体积相关，特别是 CA2-3 和基底前脑亚区 Ch1-2，但与 Ch4 无关。此外，海马体积与 PD 中的 Ch1-2 相关。Ch1-2 和视觉空间记忆之间的关系是由 CA2-3 完整性介导的。对照组的认知和体积测量之间没有相关性。我们的数据表明胆碱能基底前脑的完整性与次区域海马体积有关。此外，视觉空间功能和胆碱能核之间的关系确实存在，但完全由海马结构的变化介导。