Cerebral microbleeds and Alzheimer'sdisease

Abstract

Introduction In Alzheimer's disease (AD), cerebral microbleeds (CMBs) are of special interest as they may have a crucial role in the pathophysiology of the disorder. Moreover, they may affect the clinical course of the disease and may have therapeutic consequences. This chapter will review the available data that help in considering the meaning of CMBs in clinical terms and the underlying pathology in the context of AD. Prevalence of cerebral microbleeds in Alzheimer's disease Five studies have reported the prevalence of CMBs in patients with AD (Table 13.1) [1-5]. One study reported the prevalence of lobar CMBs in 61 demented patients, half having AD [6]. Unfortunately, data from the AD subgroup could not be extracted. In total, we have extracted data from 450 patients with AD and the prevalence of CMBs was 22% (95% confidence interval (CI), 18-26) (Table 13.1). Figure 13.1 shows the prevalence of CMBs in different disease settings compared with that in AD. Even when CMBs are quite prevalent in a disorder, the majority of patients with CMBs only show one CMB. It is possible that CMBs exert their effect in a dose-dependent manner, so a high number of CMBs would predispose to a more aggressive disease course. Whether or not one or only a few CMBs should be regarded as silent lesions without clinical implications, remains to be demonstrated in large studies of sufficient power.