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 mm3 versus 0-299 mm3-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.