11 - Vascular dementia

Summary

Introduction

Improvement in overall standard of living and advances in medical sciences have led to significant improvements in life expectancy in the last century. With the aging of the population, dementing illness becomes an important cause of concern in developed countries. After Alzheimer's disease, vascular dementia is the second most common cause of dementia.

The incidence and prevalence of vascular dementia in young individuals are unknown. They are expected to be low since cerebrovascular diseases are uncommon in individuals less than 50 years old. Depending on the instrument used in the diagnosis and the age of the study population the prevalence of vascular dementia in the geriatric population ranges from 1–5% (1–8). The incidence of dementia in the elderly population is about 0.5–1.5 per 100 person-years.

Etiology

The name “vascular dementia” implies that the dementia is secondary with interference to the vascular supply of the brain. This may take the form of cerebral infarct or intracerebral hemorrhage. Although vascular events such as subdural hematoma or subarachnoid hemorrhage (without concomitant intracerebral hemorrhage or infarct) can cause significant decline of cognitive state, they are not, by convention, considered to be causes of vascular dementia. The causes of vascular dementia are listed in Table 11.1.

Single, strategic infarct can cause significant cognitive deficit in patients (Table 11.2). Recurrent cerebral infarctions are by far the more common cause of vascular dementia. The infarcts may involve the cerebral cortex, the cerebral white matter, or the deep gray nuclei. Infarcts affecting the brainstem and/or cerebellum, by themselves, do not cause cognitive impairment. As indicated in Table 11.1, cerebral infarcts are results of thromboembolic occlusion of cerebral arteries or hypoperfusion from many causes.