Incidental Cerebral Microbleeds and Cerebral Blood Flow in Elderly Individuals

Abstract

IMPORTANCE Cerebral microbleeds (CMBs) are collections of blood breakdown products that are a common incidental finding in magnetic resonance imaging of elderly individuals. Cerebral microbleeds are associated with cognitive deficits, but the mechanism is unclear. Studies show that individuals with CMBs related to symptomatic cerebral amyloid angiopathy have abnormal vascular reactivity and cerebral blood flow (CBF), but, to our knowledge, abnormalities in cerebral blood flow have not been reported for healthy individuals with incidental CMBs.OBJECTIVE To evaluate the association of incidental CMBs with resting-state CBF, cerebral metabolism, cerebrovascular disease, β-amyloid (Aβ), and cognition.

Cerebral blood flow and metabolism associated with cerebral microbleeds in small vessel disease

“…They also showed that the increased volume of WMLs as well as the presence of lacunar infarctions was not associated with an impaired vascular reactivity, which is consistent with our previous findings [16]. On the other hand, Gregg et al [25] reported that incidental CMBs in cortical locations, which were likely the result of cerebral amyloid angiopathy, were associated with widespread reductions in resting-state CBF in cognitively normal elderly individuals. In the present study, group II patients, whose CMBs were mainly located in both the lobar and deep brain areas, exhibited reduced CBF and preserved CMRO 2 in the centrum semiovale, the terminal regions supplied by deep perforating arteries.…”

“…Although one patient in group I had a strictly lobar CMB, he had a history of long-lasting hypertension and dyslipidemia. The mean CBF value of the cortical-subcortical regions was 36.7 mL/100 g/min, and widespread reductions in the resting-state CBF as pointed out by Gregg et al [25] were not observed in this patient. As patients with subcortical CMBs could have microangiopathy related to lipohyalinotic changes instead of amyloid angiopathy in some cases [26,27], we considered that the CMB of that patient derived from hypertensive vasculopathy.…”

Apolipoprotein E and Sex Bias in Cerebrovascular Aging of Men and Mice

“…Similarly, in patients with ischemic stroke and/or transient ischemic attacks, lobar CMBs are associated with executive dysfunction[25]. Lobar CMBs are also associated with lower cerebral blood flow and hypoperfusion in both healthy elderly and in a memory clinic setting [26,27], which highlights the complex interaction of SVD with healthy ageing. Again, ApoE ε4 is associated with lobar CMBs in patients with cognitive impairment[28].…”

Molecular Neuroimaging in Vascular Cognitive Impairment

“…Another similarly well-designed recent study showed a strong correlation between incidental CMBs in cortical locations and widespread reductions in resting-state cerebral blood flow of nondemented individuals with a mean age of 86.8. 42 The most plausible explanation is indeed CAA causing both cortical CMBs and also vascular dysfunction, the latter resulting in decreased perfusion. Not surprisingly, however, CMB(+) participants did not have a higher amyloid load than CMB(−) participants, probably because of confounding by fibrillary parenchymal plaques commonly found in this old cohort.…”