Vascular Dementia Flashcards
Overview
Vascular dementia is a common form of dementia caused by cerebrovascular disease.
Vascular dementia (VD) refers to a subtype of dementia that is primarily caused by cerebrovascular disease (CVD). CVD refers to vascular brain injury or dysfunction as a result of conditions that impair cerebral blood flow including chronic small vessel disease, stroke or haemorrhage. It is the second most common form of dementia in the UK affecting around 150,000 people. It is commonly part of ‘mixed dementia’ a combination of Alzheimer’s disease (AD) and VD.
In healthcare, we measure ‘normal function’ by activities of daily living (ADLs). These are a series of routine activities that people should be able to do without assistance. They can be broadly divided into personal tasks and domestic tasks.
Personal: washing, dressing, toileting, continence, transferring (e.g. bed to chair)
Domestic: cooking, cleaning, shopping, managing finances, taking medication
Dementia can be caused by several conditions, which all manifest with poor mental performance and impaired normal functioning. The clinical manifestations of dementia can reflect the underlying aetiology.
Alzheimer’s disease (AD): 50-75% Vascular dementia (VD): 20% Dementia with Lewy-body (DLB): 15-20% Frontotemporal dementia (FTD): 2% Rare causes: Parkinson’s disease dementia (PDD), Huntington’s disease (HD), Prion disease, others.
VD epidemiology
VD is the second most common form of dementia with >150,000 people in the UK with the condition. Vascular disease is a contributing factor in up to 50% of cases of dementia.
Vascular cognitive impairment (VCI) refers to a syndrome of all cognitive disorders which are due to cerebrovascular disease. VD is considered the most severe form of VCI. The main forms of VD are:
Subcortical VD: Dementia caused by disease affecting the small vessels of the brain which predominantly supply the subcortical white matter.
Stroke-related VD: Development of dementia following a large cortical stroke. Up to 20% develop this within the next 6 months.
Single or multi-infarct VD: Development of dementia following a single, or multiple small strokes. It is the collective burden of cerebrovascular disease from these strokes that precipitates development of dementia.
Mixed dementia: Features of more than one type of dementia (usually VD and AD). For example, a patient may have significant cardiovascular risk factors and previous strokes but cognitive defects highly suspicious of AD. Based on neuropathological assessment, pure VD is less common than expected.
Any condition that affects the brain parenchyma by impairing cerebral blood flow (i.e. ischaemia) or causing haemorrhage can lead to vascular cognitive impairment, and therefore, VD. Causes include:
Ischaemic stroke: any cause (e.g. atrial fibrillation with emboli, carotid artery disease)
Small vessel disease: atherosclerosis due to traditional cardiovascular risk factors (hypertension, diabetes, hypercholesterolaemia, smoking)
Haemorrhage: intracerebral, subarachnoid
Other: cerebral amyloid, which is a cause of small vessel disease. Deposition of amyloid in small arteries.
CADASIL
This is an autosomal dominant inherited condition termed ‘cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy’. It is due to mutation in the NOTCH3 gene and leads to arterial thickening and occlusion.
CADASIL is characterised by recurrent migraine-type headaches, multiple strokes and progressive dementia. The average age of onset of strokes is the 5th decade of life.
VD is traditionally characterised as ‘..’ cognitive decline.
VD is traditionally characterised as ‘stepwise’ cognitive decline.
There are two classic presentations of VD include:
Post-stroke dementia: stepwise cognitive decline following a clinically diagnosed stroke.
Vascular dementia without recent stroke: stepwise cognitive decline without history of a symptomatic stroke.
The clinical features of dementia can be considered in the following domains:
Cognitive impairment: poor memory, disorientation, language problems
Behavioural and psychological symptoms of dementia (BPSD): agitation, depression, sleep cycle disturbance, motor disturbance
Disease-specific features: VD is characterised by a ‘stepwise’ decline in function. There are predominant gait abnormalities, attention, and personality changes. May have focal neurological signs (e.g. due to previous stroke)
Activities of daily living: an increasing reliance on others for assistance, problems with high-level functioning (e.g. work, finance), problems with basic personal care
There are multiple cognitive assessment tools, which are designed to test different areas of higher cortical functioning. Cognitive domains assessed include:
Attention and concentration Recent and remote memory Language Praxis: planned motor movement (e.g. perform a task) Executive function Visuospatial function
Diagnosis of VD
It is essential to exclude all reversible causes before making a diagnosis of dementia.
Patients suspected of dementia are usually referred to a memory clinic.
At memory clinic, patients undergo a formal history and examination (including medication review), full complement of baseline investigations including bloods and neuroimaging to exclude an underlying cause, and formal cognitive assessment. During these investigations, the specific type of dementia may become apparent.
There are different criteria that are used to diagnose probable vascular cognitive impairment (VCI).
Criteria for diagnosis of neurocognitive disorder:
Functional ability: inability to carry out normal functions. Represents a decline from previous functional level
Cognitive domains: impairment involving ≥2 cognitive domains (see chapter on cognitive assessment)
Differential excluded: clinical features cannot be explained by another cause (esp. psychiatric disorders and delirium)
Features supportive of vascular aetiology:
Timing of symptoms: onset in temporal association with cerebrovascular event
Clinical features: predominant decline in frontal executive function and attention
Evidence for cerebrovascular disease: on clinical assessment (e.g. history and examination) or neuroimaging (e.g. CT, MRI)
Not better explained by another disorder
Probable diagnosis vascular cognitive impairment:
Clinical criteria supported by neuroimaging evidence of cerebrovascular disease, OR
Clinical features in temporal association with one or more cerebrovascular events, OR
Clinical and/or genetic evidence of cerebrovascular disease.