Background and objective

Reserve is defined as the ability to maintain cognitive functions relatively well at a given level of pathology. Early life experiences such as education are associated with lower dementia risk in general. However, whether more years of education guards against the impact of brain alterations also in frontotemporal dementia (FTD) has not been shown in a large patient collective. Therefore, we assessed whether education is associated with relatively high cognitive performance despite the presence of [¹⁸F]-fluorodeoxyglucose positron-emission-tomography (FDG-PET) hypometabolism in FTD.

Methods

Sixty-six FTD subjects (age 67 ± 8 years) and twenty-four cognitively healthy controls (HC) were evaluated. Brain regions with FTD-related glucose hypometabolism in the contrast against HC and brain regions that correlate with the cognitive function were defined by a voxel-based analysis and individual FDG-PET values were extracted from all frontotemporal brain areas. Linear regression analysis served to test if education is associated with residualized cognitive performance and regional FDG-PET hypometabolism after controlling for global cognition.

Results

Compared to healthy controls, patients with FTD showed glucose hypometabolism in bilateral frontal and temporal brain areas whereas cognition was only associated with deteriorated glucose metabolism in the left temporal lobe. The education level was significantly correlated with the residualized cognitive performance (residuals from regression analysis between hypometabolism and cognitive function as a quantitative index of reserve) and also negatively correlated with left temporal FDG-PET hypometabolism after controlling for cognition.

Conclusions

In patients with FTD, the education level predicts the existing left temporal FDG-PET hypometabolism at the same cognition level, supporting the cognitive reserve hypothesis in FTD.

中文翻译：

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额颞痴呆的认知储备假说：FDG-PET研究

背景和目标

储备被定义为在给定的病理水平上相对良好地维持认知功能的能力。早期的生活经历（如教育）通常可降低痴呆症的风险。但是，在大型患者集体中，尚未显示出更多的受教育年限是否也可以防止额叶痴呆（FTD）引起的大脑变化的影响。因此，我们评估了尽管FTD中存在[ ¹⁸ F]-氟脱氧葡萄糖正电子发射断层扫描（FDG-PET）代谢不足，但教育是否与相对较高的认知能力相关。

方法

评估了66名FTD受试者（年龄67±8岁）和24名认知健康对照（HC）。通过基于体素的分析定义了与HC相反的，与FTD相关的葡萄糖低代谢的脑区域和与认知功能相关的脑区域，并从额颞脑区域提取了单独的FDG-PET值。线性回归分析用于检验控制整体认知后教育是否与残留的认知表现和区域性FDG-PET代谢不足有关。

结果

与健康对照相比，FTD患者在双侧额叶和颞脑区域显示葡萄糖低代谢，而认知仅与左颞叶葡萄糖代谢恶化有关。受教育程度与残存的认知能力显着相关（从代谢下降和认知功能回归分析得出的残差，作为储备的定量指标），并且与控制认知后的左颞FDG-PET代谢下降呈负相关。

结论

在FTD患者中，教育水平以相同的认知水平预测现有的左颞FDG-PET低代谢，支持FTD的认知储备假说。