Centre for Cognitive Ageing and Cognitive Epidemiology University of Edinburgh Edinburgh UK.
Department of Neuroimaging Sciences Centre for Clinical Brain Sciences University of Edinburgh Edinburgh UK.
Brain Behav. 2018 Jan 4;8(2):e00838. doi: 10.1002/brb3.838. eCollection 2018 Feb.
The hippocampus plays an important role in cognitive abilities which often decline with advancing age.
In a longitudinal study of community-dwelling adults, we investigated whether there were coupled changes in hippocampal structure and verbal memory, working memory, and processing speed between the ages of 73 ( = 655) and 76 years ( = 469). Hippocampal structure was indexed by hippocampal volume, hippocampal volume as a percentage of intracranial volume (H_ICV), fractional anisotropy (FA), mean diffusivity (MD), and longitudinal relaxation time (T1).
Mean levels of hippocampal volume, H_ICV, FA, T1, and all three cognitive abilities domains decreased, whereas MD increased, from age 73 to 76. At baseline, higher hippocampal volume was associated with better working memory and verbal memory, but none of these correlations survived correction for multiple comparisons. Higher FA, lower MD, and lower T1 at baseline were associated with better cognitive abilities in all three domains; only the correlation between baseline hippocampal MD and T1, and change in the three cognitive domains, survived correction for multiple comparisons. Individuals with higher hippocampal MD at age 73 experienced a greater decline in all three cognitive abilities between ages 73 and 76. However, no significant associations with changes in cognitive abilities were found with hippocampal volume, FA, and T1 measures at baseline. Similarly, no significant associations were found between cognitive abilities at age 73 and changes in the hippocampal MRI biomarkers between ages 73 and 76.
Our results provide evidence to better understand how the hippocampus ages in healthy adults in relation to the cognitive domains in which it is involved, suggesting that better hippocampal MD at age 73 predicts less relative decline in three important cognitive domains across the next 3 years. It can potentially assist in diagnosing early stages of aging-related neuropathologies, because in some cases, accelerated decline could predict pathologies.
海马体在认知能力中起着重要作用，而认知能力通常随着年龄的增长而下降。
在一项对社区居住成年人的纵向研究中，我们研究了在 73 岁（=655）和 76 岁（=469）之间，海马体结构和言语记忆、工作记忆和处理速度是否存在耦合变化。海马体结构由海马体体积、海马体体积占颅内体积的百分比（H_ICV）、各向异性分数（FA）、平均扩散系数（MD）和纵向弛豫时间（T1）来表示。
从 73 岁到 76 岁，海马体体积、H_ICV、FA、T1 和所有三个认知能力领域的平均水平下降，而 MD 增加。在基线时，较高的海马体体积与较好的工作记忆和言语记忆相关，但这些相关性在进行多次比较校正后均不成立。较高的 FA、较低的 MD 和较低的 T1 与所有三个领域的认知能力相关；只有基线时海马体 MD 与 T1 的相关性以及三个认知领域的变化，在进行多次比较校正后仍然成立。73 岁时海马体 MD 较高的个体，在 73 岁至 76 岁之间，所有三种认知能力的下降幅度都较大。然而，在基线时，海马体体积、FA 和 T1 测量值与认知能力的变化之间没有显著的相关性。同样，在 73 岁时认知能力与 73 岁至 76 岁之间海马体 MRI 生物标志物的变化之间也没有显著的相关性。
我们的研究结果为更好地理解健康成年人的海马体如何随着年龄的增长而衰老与它所涉及的认知领域之间的关系提供了证据，表明 73 岁时更好的海马体 MD 预示着在接下来的 3 年中，三个重要认知领域的相对下降幅度较小。这可能有助于诊断与衰老相关的神经病理学的早期阶段，因为在某些情况下，加速下降可能预示着病理。
