The Department of Neurology, Affiliated ZhongDa Hospital and Institute of Neuropsychiatry of Southeast University, Nanjing 210009, China.
J Affect Disord. 2013 May;147(1-3):277-87. doi: 10.1016/j.jad.2012.11.019. Epub 2012 Dec 25.
The functional neural network model has been a major method used to investigate mechanisms of neuropsychopathy. There is considerable evidence that late-onset depression (LOD) is the prodrome, or the early clinical manifestation, of Alzheimer's disease (AD). The default mode network (DMN) is one of the neural networks that can be used to explore the complex relationships between depressive symptoms, episodic memory deficits and other cognitive impairments. To date, no study has directly linked the DMN to LOD while focusing on episodic memory and the influence of apolipoprotein E4 (APOE4), a major genetic risk factor for AD in LOD patients.
In total, 33 remitted LOD (rLOD) patients and 33 elderly controls underwent fMRI scanning using low-frequency BOLD signal imaging during the resting state and during an episodic memory task. Furthermore, function-based functional connectivities (FCs) in the region of interesting (ROI) (posterior cingulate cortex (PCC) of the DMN) were analysed to explore interactions between disease states, task states and genetic risk factors (APOE4).
Compared to healthy control subjects (HC), the FCs between the PCC and the right medial temporal lobe of the rLOD patients were significantly stronger during rest (p<0.005) and significantly weaker (p<0.05) during performance of the task. The mode of change from rest to task performance in the HC was in contrast to the mode of change in the rLOD patients. The FCs of the rLOD patients without APOE4 were significantly increased (p<0.05) in the resting state, but the rLOD patients who carried APOE4 showed a trend toward decreased FCs.
The sample size was small. While the study was cross-sectional, we did not differentiate between the various types of antidepressants the patients used, which may have had different effects on cognitive function, especially on episodic memory.
Our results suggested that rLOD might be the prodrome, or the early clinical manifestation, of AD and that rLOD patients with APOE4 showed an increased risk for episodic memory decline and AD.
功能神经网络模型一直是研究神经精神病理学机制的主要方法。有大量证据表明，迟发性抑郁症（LOD）是阿尔茨海默病（AD）的前驱期或早期临床表现。默认模式网络（DMN）是可用于探索抑郁症状、情景记忆缺陷和其他认知障碍之间复杂关系的神经网络之一。迄今为止，尚无研究直接将 DMN 与关注情景记忆和载脂蛋白 E4（APOE4）的 LOD 联系起来，APOE4 是 LOD 患者 AD 的主要遗传风险因素。
共有 33 名缓解期 LOD（rLOD）患者和 33 名老年对照者接受 fMRI 扫描，在静息状态和情景记忆任务期间使用低频 BOLD 信号成像。此外，还分析了感兴趣区域（ROI）（DMN 的后扣带回皮层（PCC））的基于功能的功能连接（FC），以探讨疾病状态、任务状态和遗传风险因素（APOE4）之间的相互作用。
与健康对照组（HC）相比，rLOD 患者的 PCC 与右侧内侧颞叶之间的 FC 在静息时显著增强（p<0.005），在执行任务时显著减弱（p<0.05）。HC 从静息状态到任务状态的变化模式与 rLOD 患者的变化模式相反。无 APOE4 的 rLOD 患者的 FC 在静息状态下显著增加（p<0.05），但携带 APOE4 的 rLOD 患者的 FC 呈下降趋势。
样本量小。虽然研究是横断面的，但我们没有区分患者使用的各种类型的抗抑郁药，这些药物可能对认知功能，特别是情景记忆有不同的影响。
我们的研究结果表明，rLOD 可能是 AD 的前驱期或早期临床表现，携带 APOE4 的 rLOD 患者发生情景记忆下降和 AD 的风险增加。
