We aimed to analyse the association between intracranial arterial calcification on computed tomography (CT-IAC) and dementia in patients with minor stroke/transient ischaemic attack (TIA) independent of initial stroke severity and recurrent stroke. We also sought to compare the predictive value of CT-IAC assessed using visual scales versus a quantitative method, and to analyse the effect of calcification subtypes. 

Coronary arterial calcification is a widely studied risk factor for acute coronary events, but although CT-IAC is also a frequent finding in older individuals, few longitudinal studies have assessed whether its severity or site predict dementia. Given the potential clinical and mechanistic importance of any associations, we did a population-based study in patients with stroke/TIA. 

In a nested case-control study of patients with minor stroke/TIA from the population-based Oxford Vascular Study (OXVASC), the severity and location of CT-IAC in cases who developed dementia on follow-up was compared with that in age/sex-matched controls who did not (logistic regression adjusted for other risk factors). 

In OXVASC (cases/controls=200/200;mean age/standard deviation=78.0/9.3), dementia was independently associated with severity of internal carotid artery (ICA) CT-IAC on the visual scale (bilateral severe calcification–adjusted OR [aOR]=2.02,1.26-3.23,p=0.004) and as quantitative volume (top vs. bottom tertile–aOR=2.35,1.33-4.16,p=0.003), driven mainly by the small number of individuals with very high calcification volumes (≥600 mm³ vs. 0-299 mm³–aOR=6.23,1.24-31.24,p=0.026). Similar trends were observed for CT-IAC in the ICA and vertebrobasilar artery combined (top vs. bottom tertile–aOR=2.59,1.43-4.68,p=0.002), including after exclusion of recurrent stroke (aOR=2.60,1.33-5.08,p=0.005) and of patients with moderate/severe white matter disease (aOR=3.19,1.54-6.62,p=0.002). ICA CT-IAC of the medial/internal elastic lamina subtype independently predicted dementia after adjusting for qualitative (aOR=1.84,1.11-3.05,p=0.019) or quantitative (aOR=1.78,1.06-2.99,p=0.029) CT-IAC severity. 

Severity of CT-IAC is an independent predictor of dementia after stroke/TIA. The extent of any non-linearity of the association and calcification- or dementia-subtype differences should be determined in larger studies.