When two are worse than one

In this issue of Neurology , Regan et al.1 present longitudinal follow-up of 224 patients with clinically diagnosed Alzheimer disease (AD) and cerebrovascular risk factors in order to assess the potential role of cerebrovascular disease (CVD) on the course of cognitive decline associated with AD. The aim of this study was based on the recognition that CVD is a coincident finding in more than one third of patients with AD at postmortem examination and is associated with a significantly greater likelihood of expressed dementia for a given level of AD pathology.2,3 Cerebrovascular risk factors are also associated with late life brain changes and subtle cognitive impairment even among older individuals considered cognitively normal.4–6 Moreover, stroke is associated with a significantly increased risk for future dementia.7,8 Understanding the impact of CVD on dementia is also relevant to dementia treatment. No treatment improves AD, but …