Brain atrophy occurs in aging even in the absence of dementia, but it is unclear to what extent this is due to undetected preclinical Alzheimer disease. Here we examine a cross-sectional cohort (ages 18-88) free from confounding influence of preclinical Alzheimer disease, as determined by amyloid PET scans and three years of clinical evaluation post-imaging. We determine the regional strength of age-related atrophy using linear modeling of brain volumes and cortical thicknesses with age. Age-related atrophy was seen in nearly all regions, with greatest effects in the temporal lobe and subcortical regions. When modeling age with the estimated derivative of smoothed aging curves, we found that the temporal lobe declined linearly with age, subcortical regions declined faster at later ages, and frontal regions declined slower at later ages than during midlife. This age-derivative pattern was distinct from the linear measure of age-related atrophy and significantly associated with a measure of myelin. Atrophy did not detectably differ from a preclinical Alzheimer disease cohort when age ranges were matched.

即使在没有痴呆的情况下，脑萎缩也会在衰老过程中发生，但尚不清楚这在多大程度上是由于未检测到的临床前阿尔茨海默病所致。在这里，我们检查了一个横断面队列（18-88 岁），该队列不受临床前阿尔茨海默病的混杂影响，这是通过淀粉样蛋白 PET 扫描和三年的成像后临床评估确定的。我们使用脑容量和皮质厚度随年龄增长的线性模型来确定与年龄相关的萎缩的区域强度。几乎所有区域都出现了与年龄相关的萎缩，其中颞叶和皮质下区域的影响最大。当使用平滑老化曲线的估计导数对年龄进行建模时，我们发现颞叶随年龄线性下降，皮层下区域在以后的年龄下降得更快，和额叶区域在晚年比中年下降得更慢。这种年龄衍生模式不同于与年龄相关的萎缩的线性测量，并且与髓磷脂测量显着相关。当年龄范围匹配时，萎缩与临床前阿尔茨海默病队列没有明显差异。