How can I differentiate between Alzheimer's disease and vascular dementia based on clinical presentation?

Alzheimer's disease (AD) and vascular dementia (VaD) can be differentiated clinically by their distinct patterns of cognitive impairment and symptom progression. AD typically presents with a gradual onset and progressive decline in memory, especially episodic memory, along with impairments in language, visuospatial skills, and executive function as the disease advances. Early symptoms often include difficulty recalling recent events and learning new information, with relatively preserved attention in the initial stages. In contrast, VaD often has a more abrupt or stepwise onset related to cerebrovascular events, with cognitive deficits that correspond to the location and extent of vascular lesions. Executive dysfunction, slowed processing speed, and impaired attention are more prominent early features in VaD, while memory impairment may be less severe initially compared to AD.

Clinically, patients with VaD may also exhibit focal neurological signs such as hemiparesis, gait disturbances, or pseudobulbar palsy, which are uncommon in early AD. Fluctuations in cognition and mood changes may be more pronounced in VaD. The presence of vascular risk factors (e.g., hypertension, diabetes, atrial fibrillation) and a history of stroke support a diagnosis of VaD.

Neuropsychological testing can help differentiate the two: AD shows predominant deficits in episodic memory and language, whereas VaD shows more prominent executive and attentional deficits with relatively spared memory early on. Imaging findings of multiple infarcts or extensive white matter changes support VaD, while medial temporal lobe atrophy is more typical of AD.

Thus, the key clinical differentiators are the pattern and progression of cognitive impairment, presence of focal neurological signs, and vascular risk factors/history, with AD showing insidious memory-led decline and VaD showing stepwise decline with executive dysfunction and focal signs ¹ (Storey et al., 2002; Kalaria et al., 2024).