What are the key differences between Alzheimer's disease and vascular dementia?

From the Guidelines

Alzheimer's disease and vascular dementia are distinct forms of dementia with different causes, symptoms, and progression patterns, and can be differentiated based on their underlying pathophysiology and clinical manifestations, as outlined in the 2023 American Heart Association/American Stroke Association scientific statement 1. The key differences between Alzheimer's and vascular dementia lie in their etiology, with Alzheimer's characterized by the accumulation of amyloid plaques and neurofibrillary tangles in the brain, leading to gradual, progressive memory loss, whereas vascular dementia results from reduced blood flow to the brain due to stroke or small vessel disease, causing damage to brain tissue. Some of the main distinguishing features between the two include:

• Onset and progression: Alzheimer's disease typically has a gradual, progressive onset, while vascular dementia often has a sudden onset and follows a stepwise progression pattern, with periods of stability followed by sudden declines after new vascular events.
• Cognitive symptoms: Alzheimer's patients typically show early memory problems, while vascular dementia more commonly presents with executive function difficulties, such as problems with planning and organization, while memory may be relatively preserved initially.
• Physical symptoms: Physical symptoms like gait disturbances and urinary issues appear earlier in vascular dementia.
• Brain imaging: Brain imaging in Alzheimer's shows generalized atrophy, particularly in the hippocampus, while vascular dementia shows evidence of infarcts, white matter lesions, or hemorrhages, as defined in the 2023 study 1, which highlights the importance of cerebrovascular disease in the development of vascular cognitive impairment (VCI) and vascular dementia. The diagnosis and management of these two conditions should be guided by their distinct underlying pathophysiology, with Alzheimer's managed by cholinesterase inhibitors and memantine, while vascular dementia focuses on controlling cardiovascular risk factors to prevent further damage, as emphasized in the 2023 American Heart Association/American Stroke Association scientific statement 1.

From the Research

Differentiation between Alzheimer's and Vascular Dementia

• Alzheimer's disease and vascular dementia are two distinct forms of dementia, with different underlying pathologies and clinical presentations 2, 3, 4, 5, 6.
• Vascular dementia is caused by stroke or small vessel disease, while Alzheimer's disease is characterized by the accumulation of amyloid beta plaques and tau tangles in the brain 2, 3, 5.
• Cognitive assessments play an important role in aiding diagnosis, but there is a lack of clear evidence defining the cognitive abilities and tests that best distinguish between the two types of dementia 4.
• Studies have shown that donepezil, a cholinesterase inhibitor, can improve cognition and global clinical function in patients with mild to moderate Alzheimer's disease and vascular dementia 2, 3, 6.

Clinical Presentation and Diagnosis

• The clinical presentation of Alzheimer's and vascular dementia can overlap, making diagnosis difficult 2, 3, 4.
• Vascular dementia is often characterized by a step-wise decline in cognitive function, while Alzheimer's disease is typically marked by a gradual decline 3, 5.
• Imaging studies, such as diffusion tensor imaging (DTI), can help identify specific patterns of white matter alteration in patients with Alzheimer's and vascular dementia 5.
• The genu of the corpus callosum is predominantly affected in vascular dementia, while the splenium is predominantly affected in Alzheimer's disease 5.

Treatment and Management

• Donepezil has been shown to be effective in improving cognition and global clinical function in patients with mild to moderate Alzheimer's disease and vascular dementia 2, 3, 6.
• The drug is generally well tolerated, with most adverse events being mild and transient 2, 3, 6.
• Long-term efficacy data suggest that improvements in cognition, global function, or activities of daily living are maintained for about 21 to 81 weeks with donepezil 6.
• Further studies are needed to establish specific clinical diagnostic criteria and rating scales for vascular cognitive impairment 2.