The choroid plexus may be a missing link connecting poor sleep to brain aging
Poor sleep is a well-known risk factor for cognitive decline and Alzheimer’s disease, but the biological mechanisms have remained frustratingly unclear. Now, a large new study points to an unexpected culprit: the choroid plexus, a little-known structure deep within the brain that produces cerebrospinal fluid and helps clear metabolic waste.
Published in Alzheimer’s & Dementia, the study draws on data from 635 cognitively unimpaired older adults enrolled in the IGNITE Study, a multi-site investigation of exercise and cognitive training. Researchers led by Miranda G. Chappel-Farley and colleagues at the University of Pittsburgh found that individuals who reported poorer sleep quality had significantly larger choroid plexus volumes, and that this enlargement was in turn linked to smaller hippocampal volumes, reduced gray matter, and enlarged brain ventricles, hallmark signs of neurodegeneration.
What they found
The researchers measured choroid plexus volume using structural MRI scans and assessed sleep quality through two complementary methods: the Pittsburgh Sleep Quality Index (PSQI), a validated self-report questionnaire, and wrist-worn accelerometry over seven to ten days.
The link between self-reported sleep quality and choroid plexus volume was clear. Older adults who rated their sleep as poorer on the PSQI showed greater choroid plexus volume. But interestingly, the objective accelerometry measures, metrics like total sleep time, sleep efficiency, and wake after sleep onset, were not associated with choroid plexus size. This suggests that the perceived quality of sleep, rather than objectively measured sleep duration or fragmentation, may be the more relevant factor for choroid plexus changes.
The team then examined whether choroid plexus enlargement was tied to neurodegeneration. It was: greater choroid plexus volume was significantly associated with smaller hippocampal volumes, reduced total gray matter volume, and larger lateral ventricular volume. These are well-established MRI markers of brain atrophy and Alzheimer’s disease risk.
Crucially, the choroid plexus appeared to play a mediating role. Statistical models showed that choroid plexus volume partially mediated the relationship between poor self-reported sleep quality and both hippocampal atrophy and ventricular enlargement. In other words, poor sleep may contribute to neurodegeneration at least partly through changes in the choroid plexus.
The story did not stop there. The researchers also found that gray matter volume mediated the associations between choroid plexus enlargement and poorer performance across multiple cognitive domains, including episodic memory, executive function, and processing speed. This places the choroid plexus at the center of a cascade: poor sleep links to an enlarged choroid plexus, which links to gray matter atrophy, which in turn links to cognitive decline.
Why it matters
The choroid plexus is a highly vascularized epithelial structure located in the brain’s ventricles. It produces the majority of the cerebrospinal fluid (CSF) that bathes the brain and spinal cord, and it plays a critical role in the glymphatic system, the brain’s waste clearance pathway that is most active during sleep. The glymphatic system flushes out metabolic byproducts, including amyloid-beta and tau proteins that accumulate in Alzheimer’s disease.
An enlarged choroid plexus may signal dysfunction. In inflammatory states, the choroid plexus becomes engorged and leaky, disrupting CSF production and impairing waste clearance. If poor sleep triggers a chronic inflammatory response in the choroid plexus, the resulting enlargement could compromise the brain’s ability to clear toxic proteins overnight, setting the stage for neurodegeneration.
This study is one of the first to link sleep quality directly to choroid plexus morphology in a large, well-characterized sample of older adults. The findings open a new avenue for understanding why sleep disturbances are such a powerful risk factor for Alzheimer’s disease and suggest that choroid plexus imaging could serve as an early biomarker for neurodegeneration risk.
Limitations
The study has several important caveats. The cross-sectional design means causality cannot be established, the researchers cannot determine whether poor sleep causes choroid plexus enlargement or whether a pre-existing enlarged choroid plexus disrupts sleep. The absence of an association with accelerometry measures also raises questions about what aspect of “poor sleep” the PSQI is capturing that is biologically relevant. Additionally, the IGNITE cohort is predominantly white and well-educated, which limits generalizability to more diverse populations. Finally, choroid plexus volume is a relatively crude measure; future work using advanced MRI techniques could examine choroid plexus perfusion, permeability, and inflammatory status more directly.
Bottom line
Poor self-reported sleep quality in older adults is associated with an enlarged choroid plexus, which in turn is linked to brain atrophy and cognitive decline. The choroid plexus may be a key mediator of the well-established connection between sleep disruption and Alzheimer’s disease risk, potentially through its role in CSF production and glymphatic waste clearance. If confirmed in longitudinal studies, choroid plexus volume could become a valuable early marker for neurodegeneration, and interventions that improve sleep quality might help preserve choroid plexus health and, by extension, brain health in aging.
Source
Chappel-Farley MG, Sewell KR, Collins AM, Molina-Hidalgo C, Jain S, Huang H, Solis-Urra P, Oberlin LE, Grove G, Kramer AF, McAuley E, Burns JM, Hillman C, Vidoni ED, Sutton BP, Marsland AL, Kamboh MI, Kang C, Wan L, Erickson KI, Wilckens KA. Greater choroid plexus volume is linked to poor sleep, neurodegeneration, and cognitive deficits in older adults: Evidence from the IGNITE Study. Alzheimer’s & Dementia. 2026;22(7):e71627. doi:10.1002/alz.71627. PMID: 42410716.