Stroke patients are more likely to have white matter changes than age- and sex-matched controls. White matter changes are associated with an increased risk of dementia occurring after stroke: they often indicate a higher risk of stroke recurrence and they may lead to slight cognitive impairment. Besides white matter changes, vascular lesions of the brain and associated Alzheimer pathology, the summation of 2 or 3 of these mechanisms may lead to dementia in stroke patients even when each type of lesion is not severe enough to induce dementia by its own.