The prevalence of poststroke dementia (PSD) varies largely according to the composition of cohorts, setting, and delay after stroke. The cognitive syndrome of vascular dementia (VaD) is characterized by: memory deficit, dysexecutive syndrome, slowed information processing, and mood and personality changes. Cortical VaD relates to large vessel disease, cardiac emboli, and hypoperfusion. It prominently shows cortical and corticosubcortical arterial territorial and distal field infarcts. The occurrence of dementia depends on two factors: the total volume of brain loss because of infarcts and hemorrhages, and the location of these lesions. Many instances of dementia occurring in stroke patients are probably the consequence of the cumulative effect of the cerebrovascular lesions, Alzheimer pathology, and white matter changes. Patients with dementia after stroke are significantly less often treated with aspirin or warfarin than nondemented patients. Trials of secondary prevention of stroke usually exclude patients with obvious dementia.

This chapter talks about an 83-year-old man with a 3-4-year history of progressive speech difficulty. Past medical history was remarkable for hypertension and ischemic heart disease. Psychiatric history was unremarkable. General neurological exam was remarkable for bilateral cogwheeling in the upper extremities, rigid posture, and bilateral decreased arm swing. Magnetic Resonance Imaging (MRI) of the brain showed diffuse atrophy. Single-Photon Emission Computed Tomography (SPECT) showed decreased perfusion in the left temporo-parietal region. The findings suggested a diagnosis of progressive non-fluent aphasia (PNFA). The possibility of corticobasal syndrome (CBS) was also raised. A variety of neuropathological changes have been associated with PNFA. The most common are non-Alzheimer tauopathies. Alzheimer pathology has also being identified in PNFA, with some reports showing these in up to 30% of cases. In these patients, the distribution of AD pathology may be unusual, showing a frontotemporal pattern.