Cerebral microhaemorrhage and brain Aβ in healthy ageing and Alzheimer’s disease

Objectives Incidental cerebral microhaemorrhage (MH) are frequently found in older individuals scanned with susceptibility-weighted or gradient-recalled echo MRI. β-amyloid (Aβ) deposition can be imaged with 11C-PiB positron emission tomography (PET). We hypothesize that incidental lobar MH in healthy elderly individuals are associated with Aβ deposition.

Methods 84 healthy elderly (HC), 28 with mild cognitive impairment (MCI) and 26 individuals with probable Alzheimer’s Disease (AD) underwent 3T-SWI and 11C-PiB PET. 11C-PiB Scans were defined as “positive” or “negative” on visual inspection and global cortical binding was quantified normalized to cerebellar cortex (SUVR). MH were manually counted by consensus between two readers.

Results Lobar MH were present in 31% of AD, 36% of MCI and 19% of HC. Subjects with lobar MH had significantly higher mean SUVR (1.9±0.5) than those without (1.6±0.6), p<0.01. Seventy-four percent of HC with single lobar MH and 86% with multiple lobar MH were 11C-PiB-positive. Prevalence of lobar MH in 11C-PiB-positive subjects was similar in AD (31%), MCI (39%) and HC (41%). Lobar MH were present in 4/55 (7.3%) of 11C-PiB-negative HC.

Conclusions Lobar microhaemorrhages in the elderly, even in asymptomatic individuals, are strongly associated with Aβ deposition