Regional choroid plexus calcifications and their associations with aging, brain structure, and disease.

The choroid plexus (CP) maintains brain homeostasis through cerebrospinal fluid production and formation of the blood-cerebrospinal fluid barrier, and its dysfunction has been linked with aging and neurological disease. CP dysfunction may involve both enlargement and calcific tissue change, which may reflect distinct processes; yet population neuroimaging has focused on lateral ventricle CP volume, which cannot directly identify calcified tissue. Using quantitative susceptibility mapping (QSM) in 30,012 UK Biobank participants, we conducted, to our knowledge, the first large scale multi-ventricular study of CP calcification (CPcal), quantifying the lateral (LV), third (3rdV) and fourth (4thV) ventricles. We examined associations with age and sex, endocrine, nutritional and metabolic, mental and behavioral, nervous system, and circulatory diagnoses; family history of Alzheimer's disease and related dementias (ADRD); cardiometabolic traits; and brain macrostructure, white matter microstructure, and subcortical susceptibility. CPcal increased with age (largest association: LV, r = 0.191) and was greater in males in the LV and 3rdV (d = 0.249-0.359) and more prevalent in the 4thV (OR = 1.274). Greater CPcal was associated with endocrine and metabolic, psychiatric, nervous system, and circulatory disorders, with the strongest and most consistent associations observed in the 3rdV (d = 0.097 - 0.125) and persisted after adjustment for ventricular volume, particularly for diabetes (d = 0.303) and tobacco use disorder (d = 0.314). Maternal ADRD family history was associated with greater LV CPcal (d = 0.063). CPcal was also associated with cortical and subcortical volumes (r = 0.033 - 0.046), white matter microstructure (r = 0.017 - 0.042), and subcortical susceptibility (r = -0.064 - 0.131). QSM-derived CPcal is a scalable, radiation-free imaging phenotype that complements volumetry by characterizing calcific CP tissue, which is associated with cardiometabolic health, brain aging, and neurodegenerative risk, particularly in the third ventricle.