Hyposmia is common in Alzheimer's dementia (AD) and Parkinson's disease dementia (PDD). We evaluated the pattern of olfactory functional connectivity (FC) in AD and PDD to uncover neural correlates that are related to olfactory dysfunction. This study enrolled 57 patients with AD and PDD and 25 control subjects. Using a seed-based approach, we compared the resting-state network from the seed-region-of-interest in the olfactory bulb, olfactory tract, piriform cortex, and orbitofrontal cortex (OFC) between groups. The PDD group showed lower FC with striatal-thalamic-frontal regions from the olfactory bulb than the AD group. The PDD group showed lower FC from left OFC with striatal-frontal regions and lower FC from right OFC with left fronto-temporal areas than the AD group. In a correlation analysis, the FC from left OFC with right insula that differed between the PDD and control groups was positively correlated with olfactory function. The present study demonstrated that this distinct olfactory functional network pattern may represent different neural mechanisms for olfactory dysfunction in AD and PDD.

中文翻译：

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帕金森病痴呆和阿尔茨海默病的嗅觉功能网络模式

低血糖症在阿尔茨海默病痴呆 (AD) 和帕金森病痴呆 (PDD) 中很常见。我们评估了 AD 和 PDD 中嗅觉功能连接 (FC) 的模式，以揭示与嗅觉功能障碍相关的神经相关性。该研究招募了 57 名 AD 和 PDD 患者和 25 名对照受试者。使用基于种子的方法，我们比较了组间嗅球、嗅束、梨状皮层和眶额皮层 (OFC) 中感兴趣的种子区域的静息状态网络。与 AD 组相比，PDD 组在来自嗅球的纹状体 - 丘脑 - 额叶区域显示出较低的 FC。与 AD 组相比，PDD 组显示左侧 OFC 的 FC 较低，具有纹状体 - 额区，右侧 OFC 的 FC 较低，左侧额颞区。在相关分析中，PDD组和对照组之间不同的左侧OFC和右侧岛叶的FC与嗅觉功能呈正相关。本研究表明，这种独特的嗅觉功能网络模式可能代表了 AD 和 PDD 中嗅觉功能障碍的不同神经机制。