Severity of Intracranial Arterial Calcification on Computed Tomography and Risk of Dementia in Patients With Stroke or Transient Ischemic Attack: A Population‐Based Study

Background Coronary arterial calcification predicts coronary events, but although intracranial arterial calcification on CT (CT‐IAC) is a frequent finding in older individuals, few longitudinal studies have assessed whether its severity or site predict dementia. We did a population‐based study in patients with transient ischemic attack (TIA) or stroke to assess these associations. Methods In a matched case–control study of patients with minor stroke/transient ischemic attack nested in the population‐based OXVASC (Oxford Vascular Study), severity (qualitatively and semiautomated volume) and location (intimal or internal elastic lamina) 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). Results In OXVASC (cases/controls=200/200; mean age=78.0±9.3 years), dementia was independently associated with severity of internal carotid artery CT‐IAC on visual assessment (bilateral severe—adjusted OR [aOR], 2.02 [95% CI, 1.26–3.23], P =0.004) and quantitative volume (top versus bottom tertile—aOR, 2.35 [95% CI, 1.33–4.16], P =0.003), driven mainly by individuals with very high calcification volumes (≥600 mm 3 versus 0–299 mm 3 —aOR, 6.23 [95% CI, 1.24–31.24], P =0.026). Similar trends were observed for CT‐IAC in the internal carotid artery and vertebrobasilar artery combined (top versus bottom tertile—aOR, 2.59[95% CI, 1.43–4.68], P =0.002), including after exclusion of recurrent stroke (aOR, 2.60 [95% CI, 1.33–5.08], P =0.005) and patients with moderate/severe white matter disease (aOR, 3.19 [95% CI, 1.54–6.62], P =0.002). Internal carotid artery CT‐IAC of the internal elastic lamina independently predicted dementia after adjusting for qualitative (aOR, 1.84 [95% CI, 1.11–3.05, P =0.019) or quantitative (aOR, 1.78 [95% CI, 1.06–2.99], P =0.029) CT‐IAC severity. Conclusions Severity of CT‐IAC independently predicts future dementia after stroke/ transient ischemic attack. The extent of any nonlinearity and calcification‐ or dementia‐subtype differences should be determined in larger studies.