Differential diagnosis of Alzheimer’s dementia and vascular dementia - Nelson - 2007 - Article

Two types of dementia

Dementia is a disease which causes cognitive impairment. There are two typical types of dementia: Alzheimer’s dementia (AD) and vascular dementia (VD). AD is associated with cortical atrophy, and is called a cortical dementia. Memory impairments arise because of degeneration of mesial temporal structures, particularly entorhinal cortex and hippocampus.

Risk factors

Widespread, cortical neurotic plaques and neurofibrillary tangles are other important characters. Risk factors are being a woman, advanced age (60>), Down’s Syndrome, hypertension, and the presence of apolipoprotein E e 4.

Vascular dementia can result from an ischemic stroke, hemorrhagic stroke, and Binswanger’s Disease. Attenuation of periventricular white matter (leukoaraiosis), often observed in VD, is able to cause cognitive dysfunction. Risk factors are advanced age, history of hypertension, heart disease, hypercholesterimia, smoking, being a man and diabetes mellitus.

Diagnostic tools

DSM-IV is the most frequently used diagnostic tool for VD and AD. Also differentiations between subcortical/cortical and degenerative/non degenerative can be made. A problem with this is that a definitive diagnose of AD can only be established post-mortem. Another problem is the heterogeneous character of VD. To be diagnosed with VD or AD, according to DSM-IV, memory impairment plus another form of cognitive impairment and social or occupational impairment (compared to former functioning) should be found, but a delirium must be ruled out. To diagnose AD conditions of the central nervous system (Parkinson/Huntington/cerebrovascular disease), systemic conditions, substance-induced conditions and other Axis I disorders (for example major depression) should be ruled out.

Diagnostic challenges

Evidence of cognitive impairment is an important diagnostic feature, so standardized cognitive measures are needed. But there is no consensus found yet about this because of variability of participant inclusion criteria. Despite this there are two general findings: AD patients show more long-term memory impairment and VD patients show greater executive functioning impairments. Consino et al. found also that AD patients had significantly less leukoaraiosis and VD patients significantly more histories of hypertension and heart disease.

Because of these findings a new diagnosing system is proposed, based on neuropsychological test findings, neuroradiological findings, and vascular risk factors. It is very important that convergent date should be used to diagnose AD or VD. Cognitive profiles, medical information and neuroradiological information should all be used for discrimination between these two forms of dementia.