Vascular dementia

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.

Dementia

Dementia describes a clinical syndrome that is characterised by a significant deterioration in mental function that leads impairment of normal function.

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

Types of dementia

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.

For a comprehensive overview of dementia, see our Dementia note.

Dementia is a disease of older adults.

The World Health Organisation (WHO) estimates that almost 50 million people have a diagnosis of dementia worldwide.

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. 

A significant proportion of patients with dementia remain undiagnosed and up to 54% of patients with dementia require care home placement.

VD is the most severe deficit among a spectrum of vascular cognitive impairment.

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. 

Vascular dementia occurs secondary to disorders of the cerebral vasculature.

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 ‘stepwise’ cognitive decline.

Dementia can be difficult to identify due to insidious and non-specific symptoms. Many clinical features are attributable to dementia. Some are characteristic of all types of dementia, whereas others are typical of a subtype.

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

For more comprehensive information on clinical features see our Dementia note.

A formal mental status examination should be completed using a recognised cognitive assessment tool.

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

There are a variety of different cognitive assessment tools that range from basic screening tools, to in-depth assessments of each cognitive domain.

A comprehensive summary of cognitive assessment tools can be found in our Dementia note.

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).

Diagnostic criteria

The Diagnostic and Statistical Manual of Mental Disorders (DSM-V) has a diagnostic criteria for VCI. These assume that criteria are met for a mild or major neurocognitive disorder and the clinical features are consistent with a vascular aetiology. If both are present, a probable diagnosis of VCI can be made.

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.

Mild cognitive impairment

This describes cognitive deficits in one or more of the major cognitive domains, but the deficit is insufficient to interfere with independence in daily activities.

Mild cognitive impairment is an increasingly important term because it helps identify patients at risk of progressive decline towards dementia. Patients should have regular follow-up and be advised to undertake healthy brain activities (e.g. exercise, socialising).

Differential diagnosis

Dementia is a clinical syndrome that reflects deterioration from an underlying cause. The main differentials to exclude in a patient with features of dementia are the three ‘D’s:

• Depression (and other psychiatric disorders): psychosis can be a feature of dementia. 
• Drugs: consider drugs with anti-cholinergic effects (e.g. anti-histamines, anti-psychotics, anti-epileptics)
• Delirium: acute confusional state. May be prolonged recovery following acute episode.

Baseline investigations are essential to exclude an alternative diagnosis.

Typical baseline investigations involve a routine set of blood tests and neuroimaging.

Bloods

• Full blood count
• Erythrocyte sedimentation rate (ESR)
• Urea and electrolytes
• Bone profile
• HbA1c
• Liver function tests
• Thyroid function tests
• Serum B12 and folate levels

Other

• ECG
• Virology (e.g. HIV)
• ECHO (e.g. if suspected heart failure or coronary artery disease)
• Syphilis testing
• CXR

Neuroimaging

Typically magnetic resonance imaging (MRI) but CT may be used if MRI not available or unsuitable. Important to exclude an alternative diagnosis (e.g. brain tumour) and can be used to help characterised the type of dementia (e.g. small vessel disease in VD). 

VD is modifiable and preventable. Management centres on cardiovascular risk factor optimisation.

The management of VD, and dementia as a whole, should involve a full assessment of the biological, psychological and social needs of the patient. With significant deterioration in normal activities of daily living, patients will become dependent on others. This means help from families, organisation of carers, and with more advancing symptoms, need for care home placement.

There are multiple facets to management, which we summarise.

• Assess capacity and advanced care planning: ideally completed when patient still retains capacity. Consideration of advance statements/decision and appointment of lasting power of attorney.
• Physical and mental health: consider co-existing anxiety and depression. Manage physical health needs as normal. Consider delirium if any acute deterioration.
• Driving: must inform the DVLA. Check website for guidance.
• Pharmacological: (see below)
• Non-pharmacological: programmes to improve/maintain cognitive function (e.g. structured group cognitive stimulation programmes), exercise, aromatherapy, therapeutic use of music/dancing, massage.
• Managing BPSD: non-pharmacological interventions, consider referral to old-age psychiatry if difficult to control. Pharmacological therapy should be used on specialist advice.
• Care plans: people with dementia require a care manager and care plan, which include details on diagnosis, treatment, environmental modifications and review plans.
• End-of-life care: focus on physical, psychological, social and spiritual needs. Oral nutrition encouraged as long as possible. Long-term feeding (i.e. NG feeding, gastrostomy tube) inappropriate in severe dementia. No evidence for increased survival or reduced complications. Resuscitation discussions.

Addressing cardiovascular risk

Patients with suspected VD, or cerebrovascular disease, should be screened for cardiovascular risk factors and managed accordingly. If identified, these include anti-hypertensives, diabetic medications or insulin, and anti-lipid therapy.

Pharmacological therapy

Medical therapy for the treatment of dementia can only be initiated by a specialist in treating patients with dementia. The two main drugs as acetylcholinesterase inhibitors and N-methyl-D-aspartic acid receptor antagonists. However, there is limited efficacy of using these therapies in VD.

Acetylcholinesterase inhibitors such as donepezil may be used in VD if the cognitive decline cannot solely be attributed to cerebrovascular disease (i.e. could be considered in mixed dementia). This is because a significant proportion of patients with dementia with have mixed AD/VD, which may show a small amount of benefit. In general, evidence does not support use of the N-methyl-D-aspartic acid receptor antagonist memantine in VD.