Regional hyperperfusion in older adults with objectively-defined subtle cognitive decline

Area of Science:

• Neuroimaging
• Neurology
• Alzheimer's Disease Research

Background:

• Cerebral blood flow (CBF) alterations are linked to Alzheimer's disease (AD).
• Understanding CBF patterns in early AD prodromal stages is crucial for early detection and intervention.
• Current knowledge of regional CBF changes in subtle cognitive decline is limited.

Purpose of the Study:

• To investigate regional CBF patterns in cognitively unimpaired (CU), objectively-defined subtle cognitive decline (Obj-SCD), and mild cognitive impairment (MCI) participants.
• To identify specific brain regions exhibiting altered CBF during the progression of AD.
• To explore the relationship between CBF changes and early neurovascular dysregulation in prodromal AD.

Main Methods:

• Utilized arterial spin labeling MRI to quantify regional CBF.
• Analyzed data from 162 participants (80 CU, 31 Obj-SCD, 51 MCI) from the Alzheimer's Disease Neuroimaging Initiative.
• Focused on a priori regions of interest: hippocampus, inferior temporal gyrus, inferior parietal lobe, medial orbitofrontal cortex, and rostral middle frontal gyrus.

Main Results:

• Obj-SCD participants showed increased hippocampal and inferior parietal CBF compared to CU and MCI groups.
• Obj-SCD participants had higher inferior temporal CBF than MCI participants.
• An inverted-U pattern of CBF was observed across prodromal AD stages in AD-vulnerable regions, with no significant differences in frontal regions.

Conclusions:

• An inverted-U pattern of regional CBF characterizes prodromal Alzheimer's disease.
• Increased hippocampal and inferior parietal CBF in Obj-SCD may indicate early neurovascular dysregulation.
• These CBF changes reflect a complex interplay between compensatory mechanisms and early cognitive inefficiencies in the progression towards AD.