A Study on Clinical Determinants and one year Follow-Up of Dementia and Mild Cognitive Impairment Following Ischemic Stroke

Abstract

Cognitive impairment due to cerebrovascular disease is termed “Vascular Cognitive Impairment” and forms a spectrum that includes Vascular Dementia and milder forms of cognitive impairment referred to as Vascular Mild Cognitive Impairment. While Vascular Dementia is the second most common cause of dementia, the milder form Vascular Mild Cognitive Impairment is much more common. Nearly half of individuals with Vascular Mild Cognitive Impairment convert to dementia after five years. Vascular cognitive disorders are poised to become the silent epidemic of the 21st century and contribute significantly to mortality, disability, and decreased quality of life. It is now clear that Vascular Cognitive Impairment is not a single entity, but represents a complex neurological disorder that occurs as a result of interaction between vascular risk factors and brain parenchymal changes such as macro and micro infarcts, haemorrhages, white matter changes, and brain atrophy occurring in an ageing brain. Factors that determine progression of milder form Vascular Mild Cognitive Impairment to dementia are not well understood. Since Vascular Cognitive Impairment is amenable to prevention and treatment, there is a pressing need to identify factors that protect or predispose to it. Dementia is a common sequelae of stroke with a frequency ranging from 16% to 32%. In a more recent epidemiological study, the 10- year risk of dementia after stroke was estimated at 19.3%, compared to 11.0% in non-stroke controls. This twofold increase in dementia following stroke is in contrast with a nine fold increase reported in some previous studies. The large variation in rates is accounted for by variations in the populations studied as well as the criteria used for the diagnosis of dementia. As the definition of vascular dementia is currently being refined, it is timely that these studies be revisited. One aspect of this reassessment is the consideration of vascular mild cognitive impairment in stroke patients, which has thus far received little attention. 1. This study supports the high prevalence of dementia and mild cognitive impairment following stroke, especially in older individuals, and highlights the importance of cognitive reserve. 2. The contribution of cerebrovascular risk factors is not independent of the stroke risk. 3. Subcortical dementia was the most frequent subtype of Vascular Dementia in our hospital-based series. 4. Stroke volume is a significant determinant of post-stroke dementia. 5. This study suggests that cognitive performance in stroke patients may change over time. It also suggests that progression of cognitive impairment is common after stroke. 6. The cognitive impairment is not only frequent with stroke, but also significantly affects functional adaptation after the acute phase. Efforts to modify the course of acute stroke should also take into account chronic brain failure as an outcome.