Cerebral microhemorrhage and brain β-amyloid in aging and Alzheimer disease

Objectives: Incidental cerebral microhemorrhage (MH) is frequently found in older individuals scanned with susceptibility-weighted MRI (SWI) or gradient-recalled echo MRI. MH have been linked with beta-amyloid (A beta) deposition using C-11-Pittsburgh compound B (PiB) PET in Alzheimer disease (AD) and cerebral amyloid angiopathy (CAA). We hypothesized that A beta deposition in asymptomatic elderly individuals is associated with lobar MH (LMH). Methods: This was a cross-sectional study of 84 elderly healthy controls (HC), 28 subjects with mild cognitive impairment (MCI), and 26 subjects with probable AD who underwent 3-T SWI and C-11-PiB PET. C-11-PiB cortical binding was quantified normalized to cerebellar cortex (standardized uptake value ratio [SUVR]) and scans classified as positive (PiB+) or negative (PiB-) by visual inspection. MH were manually counted and categorized by region and as lobar or nonlobar. Results: LMH were present in 30.8% of AD, 35.7% of MCI, and 19.1% of HC. The prevalence of LMH among PiB+ subjects was similar, regardless of clinical classification (AD 30.8%, MCI 38.9%, HC 41.4%, p > 0.7). HC with LMH had significantly higher mean neocortical SUVR (1.7 +/- 0.5) than HC without LMH (1.3 +/- 0.3, p = 0.01). In HC, there was a positive correlation between number of LMH and SUVR, and between LMH and age. In HC, PiB+ (odds ratio [OR] 7.3, 95% confidence interval [CI] 1.6-33.7, p = 0.01) and age (OR 1.2, 95% CI 1.03-1.3, p = 0.02) both independently predicted the occurrence of LMH using logistic regression. Conclusion: Asymptomatic A beta deposition in older adults is strongly associated with LMH. Neurology (R) 2011;77:48-54