Coronary Artery Calcium and Risk of Dementia in the Multi-Ethnic Study of Atherosclerosis

Abstract

Background

Studies suggest a link between vascular injuries and dementia. Only a few studies, however, examined a longitudinal relation of subclinical vascular disease with dementia. We tested whether baseline coronary artery calcium (CAC), a biomarker of subclinical vascular disease, is associated with incident dementia independent of vascular risk factors (VRF) and APOE -ε4 genotype in a community-based sample.

Methods and Results

We analyzed 6,293 participants of the Multi-Ethnic Study of Atherosclerosis (MESA), aged 45–84 years at baseline (2000–2002), initially free of cardiovascular disease (CVD) and noticeable cognitive deficit. Dementia cases were identified using hospital and death certificate ICD codes. Cox models were used to obtain hazard ratios according to CAC category, or per 1 standard deviation (SD) log2[CAC+1], adjusted for VRF, APOE -ε4, with or without exclusion of interim stroke or CVD. We observed 271 dementia cases in a median follow-up of 12.2 years. Baseline CAC had a graded positive association with dementia risk. Compared to no CAC, CAC score of 1–400, 401–1000, and ≥1001 had increased risk of dementia by 23%, 35%, and 71%, respectively (P _trend=0.026) after adjustment. 1SD higher log2[CAC+1] was associated with 24% (95%CI: 8–41%, P=0.002) increase in dementia risk. Although the association was partially explained by interim stroke/CVD, it remained significant even after excluding the interim events, or regardless of baseline age.

Conclusions

Higher baseline CAC was significantly associated with increased risk of dementia independent of VRF, APOE -ε4, and incident stroke. This is consistent with a hypothesis that vascular injuries play a role in development of dementia.