Vascular cognitive impairment and dementia

Stroke and dementia are frequent and often associated in the same patient. Their association can be encountered either in the diagnostic workup of patients attending a memory clinic, or during the follow-up of stroke patients The term ‘vascular dementia’ (VaD) is used to describe a dementia syndrome likely to be the direct consequence of stroke lesions, while the term post-stroke dementia (PSD) is a more general term that includes all types of dementia occurring after a stroke, irrespective of the presumed cause. Therefore, VaD accounts for only a part of PSD, while it may sometimes occur without any clinical history of stroke and be the consequence of so-called ‘silent’ lesions of the brain of vascular origin. VaD is the second most common cause of dementia after Alzheimer’s disease (AD): it accounts for 10–50% of all cases of dementia, depending on regional variations and criteria used. Both ischaemic and haemorrhagic strokes lead to a high risk of cognitive impairment and dementia. About one in ten patients is demented before having a first-ever stroke, one in ten develops new-onset dementia after a first-ever stroke, and more than one in three develops dementia after a recurrent stroke. A vascular origin of cognitive impairment is frequent, and often preventable: therefore, patients could benefit from early detection and therapy. An accurate diagnosis of vascular cognitive impairment or VaD is necessary. Dementia is probably the tip of the iceberg, accounting for a small part of the cognitive consequences of stroke, as most of these consequences are represented by cognitive impairment without dementia, and are due to the coexistence of vascular and degenerative lesions of the brain.