# Association between MRI indicators of the glymphatic system and cognition in high-risk populations for Alzheimer's disease

## TL;DR

This study finds that MRI indicators of the glymphatic system are linked to cognitive decline in people at high risk for Alzheimer's disease.

## Contribution

The study identifies early glymphatic system dysfunction in Alzheimer's disease using MRI markers and links them to cognitive performance.

## Key findings

- Increased PVS burden in the basal ganglia correlates with worse attention in MCI patients.
- Lower ALPS index in MCI patients is associated with poorer memory performance.
- Glymphatic dysfunction is detectable in preclinical Alzheimer's stages.

## Abstract

•Glymphatic function characterized by ALPS index becomes abnormal in the early stages of AD.•The PVS burden in the basal ganglia region becomes abnormal in MCI patients.•The PVS burden and ALPS index are closely associated with several cognitive scales.

Glymphatic function characterized by ALPS index becomes abnormal in the early stages of AD.

The PVS burden in the basal ganglia region becomes abnormal in MCI patients.

The PVS burden and ALPS index are closely associated with several cognitive scales.

Using the Diffusion Tensor Image Analysis Along the Perivascular Space (ALPS) method and perivascular space (PVS) burden to study glymphatic function in high-risk Alzheimer's disease (AD) populations, this research investigates the correlation between ALPS index and PVS volume with cognitive function respectively.

This study enrolled 126 participants, including 21 cognitively unimpaired (CU) individuals, 68 with subjective cognitive decline (SCD), and 37 with mild cognitive impairment (MCI). All participants underwent MRI and cognitive assessments. MRI measures, including the PVS burden and the ALPS index, were compared across SCD, MCI, and CU groups. Additionally, correlations among the ALPS index, PVS burden, and cognitive scales were analyzed.

The PVS in the basal ganglia volume fraction (PVSVF-BG) in patients with MCI was significantly larger than the fraction in CUs (p < 0.05) and a higher PVSVF-BG was associated with poorer performance on the Trail Making Test A (TMTA) (r = 0.29, p < 0.05). Compared with the CU and SCD groups, patients with MCI exhibited a significantly lower ALPS index in both the left (p < 0.05) and right hemispheres (p < 0.001). Lower whole brain ALPS index in patients with MCI was correlated with worse performance in the Auditory Verbal Learning Test(AVLT) (N4, r = 0.33, p < 0.05; N7, r = 0.56, p < 0.001).

An increased PVS burden and a decreased ALPS index can be observed in the preclinical stage of AD, which may suggest impaired glymphatic system function. These impairments were further correlated with worse cognitive performance in terms of attention in SCD and memory in MCI.

Image, graphical abstract