Intracranial Internal Carotid Artery Calcification Is Not Predictive of Future Cognitive Decline
Abstract BackgroundIntracranial internal carotid artery (ICA) calcification is a common incidental finding in non-contrast head CT. We evaluated the predictive value of ICA calcification for future risk of dementia and compared the results with conventional imaging biomarkers of dementia.MethodsIn a retrospective observational cohort, we included 230 participants with a PET-CT scan within 18 months of a baseline clinical assessment and longitudinal imaging assessments. Intracranial ICA calcification was quantified on baseline CT scans using the Agatson calcium score. The ability of baseline ICA calcification to discriminate between a control group (participants who maintained a Clinical Dementia Rating (CDR™) score of zero over all follow-up visits) and a converter group (participants who had a baseline CDR of zero but received a persistent CDR>0 at any follow-up visit) was evaluated along with the predictive value of baseline ICA calcification for longitudinal clinical and imaging biomarkers. ResultsBaseline ICA calcium score could not distinguish participants who converted to CDR>0. ICA calcium score was also unable to predict longitudinal changes in cognitive scores, imaging biomarkers of small vessel disease such as white matter hyperintensities (WMH) volume, or AD such as hippocampal volume, AD cortical signature thickness, and amyloid burden. Severity of intracranial ICA calcification increased with age, male sex, and higher WMH volumes at baseline visit. Higher WMH volume and amyloid burden as well as lower hippocampal volume and AD cortical signature thickness at baseline predicted lower Mini-Mental State Exam scores at longitudinal follow-up. Baseline ICA calcification was indirectly associated with longitudinal cognitive decline, fully mediated through WMH volume.ConclusionsIn elderly and preclinical AD populations, atherosclerosis of large intracranial vessels as demonstrated through ICA calcification is not directly associated with a future risk of dementia, cognitive impairment, or progression of imaging biomarkers of AD or small vessel disease.