Analysis of cerebral lobar microbleeds and a decreased cerebral blood flow in a memory clinic setting

Cerebral microbleeds (MBs) have been previously associated with cognitive dysfunction, including Alzheimer's disease. In the present study, we aimed to clarify the relationship between cerebral lobar MBs and the regional cerebral blood flow (CBF).

We investigated the data obtained from 122 patients in our memory clinic who were examined by both MRI and (99m)Tc-ethyl cysteinate dimer (ECD)-single photon emission computed tomography (SPECT). Patient brain scans were superimposed and brain regions containing both decreased CBF and MBs were visually identified. For each patient eight brain regions were evaluated, comprising the right and left frontal, temporal, parietal, and occipital lobes.

Cerebral MBs were detected in 36 of the 122 (29.5%) patients. Of these 36 patients, 23 had detectable lobar MBs, which were primarily distributed in the occipital lobe in 19 of the 46 (41.3%) regions with lobar MBs. The frequency of MBs accompanied by a decreased CBF in the parietal and occipital lobes was significantly higher than that observed in the frontal lobe (73.3% vs. 27.3%, p<0.05, and 73.7% vs. 27.3%, p<0.05, respectively). Additionally, a decreased CBF was observed significantly more frequently in the brain regions with 5 or more MBs compared to the regions with one microbleed (83.3 vs. 25.0%, p<0.0005). Among the 17 patients with observable MBs accompanied by a decreased CBF, none were initially diagnosed with either subjective complaints or mild cognitive impairment.

We determined that the cerebral lobar MBs located in the parietal and occipital lobes, and the lobar regions with a large number of MBs, were significantly more likely to be accompanied by a decreased CBF.