Vascular Cognitive Impairment: An Overview

Dementia is a huge and growing global problem, with up to 25 million cases worldwide and a new case developing every seven seconds (Ferri et al., 2005). Numbers are set to double in the next 25 years and double again in the next 25, thus showing an exponential rise. Costs to health and social care are enormous, with a recent UK Alzheimer’s Research Trust report estimating that annual costs of dementia care were five times as high as people with other common diseases such as stroke, heart disease or cancer (ART, 2010). Dementia is age-related, with both prevalence and incidence rising with age. Around 5% of the over 65s are affected, rising to 20% of the over 80s and up to 50% of the very old old – in their 90s. Dementia refers to a global cognitive decline which can have a number of causes. Once several other pathologies or potentially reversible causes (such as space occupying lesions, vitamin deficiencies, or psychiatric disorders) are excluded, the most common causes in late life are Alzheimer’s disease, responsible for around 60% of cases, vascular dementia, responsible for 15-20% of cases, and dementia with Lewy bodies, responsible for around 15% of cases. Other causes include late onset frontotemporal dementia, dementia due to Huntington’s disease, and a range of other less common degenerative, metabolic and infective causes. The importance of vascular factors is recognised by the presence of significant vascular pathology in a third of dementia cases acquired from community registers (MRC CFAS, 2001). Rates of vascular dementia rise with age, as for Alzheimer’s disease, doubling approximately every 5.3 years as opposed to every 4.5 years for dementia (Jorm et al., 1987). Dementia affects around 15-20% of people three months after stroke, and a further 20-25% develop delayed dementia after stroke, which may be vascular, but increasingly a degenerative component to such delayed dementia after stroke is recognised (Pendlebury and Rothwell, 2009).