Cognitive profiles in Alzheimer’s disease

• Alzheimer’s disease
• vascular dementia

In the paper by Graham et al (see pp 61–71, this issue)¹ the authors provide a useful foundation for delineating the neuropsychological profile of a well defined group of subjects with vascular dementia and for differentiating this profile from that typically associated with Alzheimer’s disease. One of the main weaknesses in previous studies that attempted to characterise the neuropsychological profile of subjects with vascular dementia has been the within group heterogeneity. Unlike Alzheimer’s disease, in which well established, validated diagnostic criteria exist, multiple clinical criteria for the diagnosis of vascular dementia have been proposed.² Acceptable sensitivity and specificity for the detection of vascular dementia in clinical practice have yet to be established for any of the proposed clinical criteria,³ and application of different criteria has resulted in wide variations in the prevalence of vascular dementia.⁴ The primary focus in establishing clinical criteria for vascular dementia has been the identification of vascular factors; relevant neuroimaging findings, focal neurological signs, and establishing a temporal relationship between symptoms and cerebrovascular events, although minimal attention has been paid to defining the dementia in vascular dementia. Similar to clinical features used to define Alzheimer’s disease dementia, the clinical symptoms required for the identification of dementia in vascular dementia frequently emphasise memory impairment as the primary criterion. However, despite the limitations of previous research due to the lack of uniform diagnostic criteria, as well as the individual variability associated with cerebrovascular disease, the most consistent finding that has emerged regarding the neuropsychological profile in vascular dementia has been the relative preservation of memory functioning as compared with subjects with Alzheimer’s disease.⁵ This finding, as well as other characteristic neuropsychological impairments as described in the current study, may eventually lead to an improvement in the ability to accurately diagnose vascular dementia in the clinical setting. Continued research is needed in this area, including clinicopathological studies, to further refine the clinical profile in vascular dementia and improve the specificity of diagnostic criteria.