The hippocampus is a plastic region and highly susceptible to ageing and dementia. Previous studies explicitly imposed a priori models of hippocampus when investigating ageing and dementia-specific atrophy but led to inconsistent results. Consequently, the basic question of whether macrostructural changes follow a cytoarchitectonic or functional organization across the adult lifespan and in age-related neurodegenerative disease remained open. The aim of this cross-sectional study was to identify the spatial pattern of hippocampus differentiation based on structural covariance with a data-driven approach across structural MRI data of large cohorts (n = 2594). We examined the pattern of structural covariance of hippocampus voxels in young, middle-aged, elderly, mild cognitive impairment and dementia disease samples by applying a clustering algorithm revealing differentiation in structural covariance within the hippocampus. In all the healthy and in the mild cognitive impaired participants, the hippocampus was robustly divided into anterior, lateral and medial subregions reminiscent of cytoarchitectonic division. In contrast, in dementia patients, the pattern of subdivision was closer to known functional differentiation into an anterior, body and tail subregions. These results not only contribute to a better understanding of co-plasticity and co-atrophy in the hippocampus across the lifespan and in dementia, but also provide robust data-driven spatial representations (i.e. maps) for structural studies.

中文翻译：

---

痴呆症中的海马体共萎缩模式与整个生命周期的协方差模式不同。

海马体是一个可塑性区域，极易衰老和痴呆。先前的研究在调查衰老和痴呆症特异性萎缩时明确施加了海马体的先验模型，但导致结果不一致。因此，宏观结构变化是否遵循成人生命周期和与年龄相关的神经退行性疾病的细胞结构或功能组织的基本问题仍然存在。这项横断面研究的目的是基于结构协方差，使用数据驱动的方法来识别大型队列的结构 MRI 数据（n  = 2594）。我们通过应用揭示海马内结构协方差差异的聚类算法，检查了年轻、中年、老年人、轻度认知障碍和痴呆症样本中海马体素的结构协方差模式。在所有健康和轻度认知障碍的参与者中，海马体被有力地分为前、外侧和内侧亚区，让人联想到细胞结构分裂。相比之下，在痴呆患者中，细分模式更接近于已知的功能分化为前部、身体和尾部亚区。这些结果不仅有助于更好地了解整个生命周期和痴呆症海马体的共可塑性和共萎缩，而且还提供了强大的数据驱动的空间表示（即