Prevalence and cognitive impact of cerebrovascular findings in Alzheimer's disease: a retrospective, naturalistic study

Aims: Cerebrovascular disease (CVD) is a major risk factor for cognitive decline associated with progression to Alzheimer's disease (AD) and dementia. The objective of this study was to retrospectively assess the prevalence of CVD and its cognitive impact in patients with AD in everyday clinical practice. Methods: Medical notes were retrospectively reviewed for all individuals who presented at East Sussex Memory Clinic (2004-2008) for investigation of cognitive impairment and had brain magnetic resonance imaging (MRI) as part of their clinical work-up. Global cognitive status was assessed with Mini-Mental State Examination (MMSE) and Cambridge Cognitive Examination. The extent of cerebrovascular abnormalities was qualitatively evaluated with MRI. Results: Notes were reviewed for 232 patients (109 males, 123 females), mean age 76 years (range 62-93), who underwent MRI. Of these, 167 (72%) patients were diagnosed with AD. CVD was present in 89% of AD patients and 47% of patients had moderate to severe cerebrovascular abnormalities. The majority of patients (57%) had MMSE scores in the 21-26 range, indicative of mild AD. There was a trend towards worse cognitive status in patients with more severe CVD, which did not reach significance. Hachinski Ischaemic score indicated these patients did not have vascular dementia (VaD) (mean ± standard deviation 1.1 ± 1.3). Conclusion: These findings, based on qualitative MRI, indicate that cerebrovascular pathology is a very common associated feature in patients with mild to moderate AD, without VaD. Although the study suggests that CVD does not contribute to cognitive decline, and is not associated with the development of VaD, a non-significant trend was observed towards worsening cognitive status with increasing severity of CVD. The finding of this trend suggests a need for additional research, especially a prospective quantitative method of assessing CVD, to improve our understanding of how CVD contributes to cognitive impairment in AD. © 2008 Blackwell Publishing Ltd.