# Microscopic white matter changes in the cingulum contribute to memory impairment among older adults with obstructive sleep apnea in the memory clinic

## TL;DR

Older adults with sleep apnea show brain white matter changes linked to memory problems, especially in the cingulum pathway.

## Contribution

This study identifies a novel mechanistic link between obstructive sleep apnea and memory impairment via white matter changes in the cingulum.

## Key findings

- Mild OSA is associated with white matter changes in the anterior thalamic radiation, uncinate fasciculus, and fornix.
- Moderate and severe OSA are linked to cingulum and fornix alterations, which correlate with worse verbal learning and memory.
- Cingulum changes are associated with memory impairment independent of hippocampal volume.

## Abstract

Obstructive sleep apnea (OSA) is prevalent in memory clinic patients and is associated with learning and memory deficits. In a memory clinic sample, we investigated the relationship between memory‐related white matter pathways and OSA.

Eighty‐two participants (mean age 67.0) underwent neuropsychological testing and neuroimaging. Fixel‐based white matter analyses were conducted in the anterior thalamic radiation (ATR), cingulum, uncinate fasciculus (UF), and fornix. Oxygen desaturation index (ODI) from overnight polysomnography classified participants as controls (ODI < 5, n = 26), mild OSA (ODI 5–14, n = 32), or moderate and severe OSA (ODI ≥ 15, n = 24).

In mild OSA, white matter changes were seen in the ATR, UF, and fornix. In moderate and severe OSA, alterations were observed in the cingulum and fornix. Cingulum changes were linked to poorer verbal learning and memory.

OSA is associated with disrupted memory‐related pathways. Cingulum changes are associated with memory performance in moderate and severe cases.

Fixel‐based white matter analysis in older adults attending memory clinics revealed widespread microstructure alterations in mild obstructive sleep apnea (OSA), particularly in the anterior thalamic radiation, uncinate fasciculus, and fornix.Moderate and severe OSA were associated with white matter alterations predominantly in the cingulum and fornix.Cingulum alterations were associated with poorer verbal learning and memory, independent of hippocampal volume.Findings suggest a novel mechanistic link between OSA‐related white matter changes and cognitive impairment in older adults with subjective cognitive impairment and mild cognitive impairment.

Fixel‐based white matter analysis in older adults attending memory clinics revealed widespread microstructure alterations in mild obstructive sleep apnea (OSA), particularly in the anterior thalamic radiation, uncinate fasciculus, and fornix.

Moderate and severe OSA were associated with white matter alterations predominantly in the cingulum and fornix.

Cingulum alterations were associated with poorer verbal learning and memory, independent of hippocampal volume.

Findings suggest a novel mechanistic link between OSA‐related white matter changes and cognitive impairment in older adults with subjective cognitive impairment and mild cognitive impairment.