Coronary artery calcium and risk of dementia in MESA (Multi-Ethnic Study of Atherosclerosis)

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 and APOE-e4 genotype in a community-based sample. Methods and Results-We analyzed 6293 participants of MESA (Multi-Ethnic Study of Atherosclerosis), aged 45 to 84 years at baseline (2000-2002), initially free of cardiovascular disease and noticeable cognitive deficit. Dementia cases were identified using hospital and death certificate International Statistical Classification of Diseases and Related Health Problems codes. Cox models were used to obtain hazard ratios according to CAC category, or per 1 SD log2[CAC+1], adjusted for vascular risk factor, APOE-e4, with or without exclusion of interim stroke or cardiovascular disease. 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 with no CAC, CAC score of 1 to 400, 401 to 1000, and =1001 had increased risk of dementia by 23%, 35%, and 71%, respectively, (Ptrend=0.026) after adjustment. 1 SD higher log2[CAC+1] was associated with 24% (95% confidence interval, 8%-41%; P=0.002) increase in dementia risk. Although the association was partially explained by interim stroke/cardiovascular disease, 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 vascular risk factor, APOE-e4, and incident stroke. This is consistent with a hypothesis that vascular injuries play a role in the development of dementia.