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Dementia

Dr Tom Leach
Confusion

Confusion

Introduction

Dementia is a progressive global decline cognitive function, without impairment of consciousness. It is typically defined as a syndrome secondary to one or more of multiple causes, rather than a diagnosis in its own right.

The causes of dementia include:
  • Degenerative cerebral diseases:
    • Alzheimer’s disease (~50%)
    • Lewy Body dementia (10%)
    • Frontal lobe dementia (10%)
  • Diffuse vascular disease (aka multi-infarct dementia) ~25%
  • In practice it is often difficult to differentiate the type of dementia present. There may also be a mixture of causes

Poor memory is the main and often first symptom. Short-term memory is usually the worst affected and in mild to moderate disease, long-term memory is often remarkably well preserved. As the disease advances other cognitive ability is affected, including verbal skills, abstract thinking, judgement and the ability to perform complex tasks.

Depression is a common differential diagnosis for dementia, and the two also often co-exist.

Mild Cognitive Impairment (MCI) is defined a decline in cognitive function which does not affect day to day functioning. It is often seen as a pre-cursor to dementia – 50% of those with MCI go on to develop dementia.

Dementia is associated with increased mortality, and has a large economic impact.

Epidemiology

  • Very rare <55 years
  • 5-10% prevalence in >65’s
  • 20% in >80 years
  • 80% in >100 years
  • Female:Male ratio = 2:1
  • The incidence of dementia is declining slightly, however the total number of sufferers of the condition is increasing due to increasing life expectancy

Aetiology

Alzheimer’s disease
  • Genetic predisposition
    • About 15% of cases are familial. These fall into to two categories:
    • An early onset autosomal dominant disease
      • PSEN-1 and PSEN-2 genes are associated with early onset Alzheimer’s
    • A later onset type of disease, whose inheritance is variable
      • The most common gene mutation is apoE4 although mutation of this gene does not necessarily mean you will develop Alzheimer’s
      • APO genes are involved with the breakdown of beta-amyloid plaques
      • The apoE4 variant is particularly poor at this task
    • Down Syndrome is also associated with an increased risk of early onset Alzheimers because as part of the trisomy, they inherit an extra APP genes, and presumably express more APP (a precursor of beta-amyloid plaques – see pathology below)
  • Insulin resistance may be a predisposing factor
  • The majority of cases are sporadic with no obviously identifiable cause
  • Risk factors

Symptoms

General symptoms of dementia
  • Memory loss – this is usually the first symptom to appear
    • The damage to brain tissue is not universal, and thus some areas of memory, notably autobiographical and political memory is stored in areas that are less often affected.
    • Short term memory is more readily affected, and confusion may often result. For example, patients may buy many identical items of food on separate occasions, and then wonder why their cupboards are full of these items.
  • Visuo-spatial problems – patients may be easily disorientated by unfamiliar surroundings
  • Emotional disturbance
  • Loss of normal social behaviour
  • Language problems  – Problems both understanding what is being said, and naming objects
  • Concentration issues
  • Short attention span – Also unable to plan, organise, or sequence activities
  • Behavioural changes – Delusions (persecutory), agitiation, aggression, wandering
  • Variable mood
  • Poor sleep
  • Restlessness
  • Hallucinations
  • Apathy
  • Depression / euphoria – Severe depression is rare, due to loss of insight
In later stages of the disease, there may also be:
  • Self-neglect, e.g.
  • Change in personality – which generally involves loss of inhibition. This can include previously very uncharacteristic behaviour, such as:
    • Sexual promiscuity
    • Aggression
    • Anti-social behaviour
    • Violence
  • Motor and sensory abnormalities
  • Seizures
In very late stage disease there may be:
  • The patient may become mute
  • They may take little interest in anything
  • Parkinsonism
  • Wasting
  • Seizures
  • Incontinence
These later symptoms can be particularly distressing for relatives and carers.

Presentation

On first presentation, the signs and symptoms may be mild and variable. History is very important, and almost always should involve a collateral history from a relative, friend or carer. Dementia is slowly progressive, and the symptoms may have started years ago.

Common ways dementia can present are outlined below:

The Patient

  • Muddled complaints
  • Multiple presentations of confusion
  • Relapses of previously well-controlled physical disorders
  • Strange or uncharacteristic behaviour
    • Disinhibited
    • Risk taking
    • Aggression
  • Reduced self-care and personal hygiene

Relatives or carers

  • Report change in personality
  • Unsafe driving
  • False accusations against family members or others
  • Emotional, irritable
  • Wanders off (e.g. in the street)
  • Losing items around the house
  • Confused waking in the night

On Observation

  • Vague, rambling conversations
  • Difficulty putting events in chronological order
  • Repeating phrases
  • Avoidance of memory testing

Diagnosis

The main symptom of dementia is usually reduced memory. Diagnosis is usually clinical, and made with the help of the MMSE (Mini-Mental State Exam) or similar – e.g. MOCA.
  • Patients with a higher IQ have been shown to score more highly on MMSE, despite early dementia
  • Sometimes, IQ tests (Wechsler Adult Intelligence Scale, may also be used).

However, as confusion is often apparent, you may have to perform many other tests to rule out other differentials. The later on in life the presentation, the less likely it is to be investigated.

The DSM-IV criteria for the diagnosis of dementia include:

Differentials

Differentials for acute confusion (delirium):

The diagnosis of dementia is usually clinical, but often at the time of diagnosis / on the first presentation investigations are performed to rule out other differentials. Always assume confusion is due to an acute illness until proven otherwise.
  • Frequently, patients with dementia will suffer from acute delirium, secondary to an overlying disorder (most commonly UTI or another infection).

Differentiating depression and dementia

  • Dementia often has an insidious and poorly defined onset, whilst for depression this is often more clear cut
  • Patients with depression often have a past history of depression or another mental health disorder
  • Patients with depression often have insight, those with dementia do not
  • Patients with depression often complain about their inability to do their normal activities, and how difficult these activities seem, whilst patients with dementia often don’t realise that they are not capable of looking after themselves appropriately
  • In memory testing
    • Patients with depression often report they “don’t know” the answers
    • Patients with dementia will usually attempt an answer, even if it is marginally (or widely – and sometimes comically) incorrect
  • Remember that depression and dementia frequently co-exist – especially in the early stages of dementia

Investigations

Investigations might include:

  • Vitamin deficiencies – ↓folate, ↓B12, (↓thiamine and ↓vit D  –not routinely tested but may be supplemented), – these could be primary deficiencies, or may be alcohol related.
  • TFT’s – thyroid problems
  • FBC – anaemia
  • Calcium
  • U+E’s – renal failure / dehydration
  • LFT’s – carcinoma, cirrhosis, encephalopathy
  • Glucose / HbA1c – diabetes
  • CRP/ESR – acute infection
  • Imaging of the brain – CT/MRI – this may be used to exclude treatable space occupying lesions, such as:
    • Hydrocephalus
    • Tumour  metastases
    • Subdural haematoma
    • HOWEVER – the most common abnormality seen on brain scan is general atrophy.
  • Other investigations to consider if specifically indicated:
    • CXR
    • Fasting lipid profile
    • ECG
    • MSU / urine MC+s
    • Syphilis and HIV serology

Pathogenesis

Alzheimer’s disease

Pathological processes

It is believed that there are two important underlying pathological processes:

Beta-amyloid plaques

Tangles

Other pathological effects

Vascular dementia

This is the result of many small infarcts. Cerebrovascular disease is usually well advanced for vascular dementia to become apparent, as large parts of the cortex have to be affected for patients to be symptomatic.
The disease will have a step-wise progression, so for instance, there will be no apparent change in the condition, perhaps for many months, and then there is a sudden drop in function. Infarcts are particularly likely to affect function if they damage the white matter.
As well as dementia, eventually there may be:
There is often also a history if TIA’s

Lewy body dementia

Differentiating types of dementia

The type of dementia can be differentiated by a combination of; history, CT/MRI and neuropsychological testing. This may be clinically relevant, as treatment is different, e.g.:

Management

In all types of the disease, the management is only able to reduce the rate of progression of the disease. There is no cure.
Management includes social support, management of risk factors for further progression, and consideration of medical therapy.
It is also important to discuss the patient’s ability to drive.

I can recall several stories of patients known to me – whom, despite no longer having a driving license (and in some cases not even their own car), have been found to go driving. On one occasion, a patient of mine took his old, unregistered vehicle for a 20km joyride to the next town, was given several tickets by police (unregistered vehicle, driving without a license) – and then was subsequently allowed to drive home! I have no idea how he managed to find his way back again. – Dr Tom Leach

Non-medical management

Advanced Care Planning and making a will

It is frequently possible for the patient to still make a valid will and/or an advanced directive before the patient becomes to ill for one of these to be accepted by law, so long as the patient is deemed to be competent (i.e. has capacity) to make such decisions. Adults should be assumed to have capacity unless proven otherwise, and should be offered all available support to help them make appropriate decisions. For a patient to be deemed to have capacity, the patient must be able to:

Where is patient is deemed not competent to make a decision, then decision makers must be seen to act in the patient’s best interest – e.g. in medical care – when deciding on a treatment option (or deciding not to treat).

Relatives and carers should be involved in management decisions wherever possible.

Alzheimer ’s disease

Drug therapy is controversial

Anticholinesterase drugs – e.g. donepezil, galantamine, rivastigmine
NMDA receptor antagonists – memantine
Drug treatment should only be initiated in those with a MMSE of >12!

This is mild to moderate dementia
NICE guidelines state:

Antipsychotic medications

Vascular Dementia

Prevention
Reduction of vascular risk factors:
The burden of care
The course of the disease is often distressing for both families and patient. Supportive care is necessary to ensure the patient stays in a familiar home environment as long as possible. Often the burden of care falls to relatives.
Dementia and Parkinson’s Disease

Prevention

There is evidence that lifestyle factors reduce the risk of dementia. Correcting these factors can also slow the progression of dementia in patients who have already been diagnosed. Factors include:

Other Types of Dementia

Vascular dementia
In Alzheimer’s disease the progression of the symptoms is always gradual, but in vascular dementia, the symptoms often being acutely followed by a ‘step-wise progression’’. This is due to the pathology -vascular dementia is the result of multiple acute ischaemic events causing damage to specific brain areas.
In cases of vascular dementia you may also find other vascular sings, for example:
  • Raised BP
  • Past strokes
  • Sudden onset / stepwise increase of symptoms
Lewy-body dementia (~15-25% of all cases of dementia)
This is characterised by the presence of Lewy bodies in the brainstem and neocortex. Also sometimes referred to as Pick’s Disease – although technically Pick’s disease is a sub-type of Lewy Body dementia. It can be differentiated from other types of dementia by:
The drug rivastigmine may help to improve symptoms.

Diagnostic criteria include two of:

  • Visual hallucinations
  • Parkinsonism
  • Fluctuating mental state

Differentiating Lewy Body Dementia is important because in these patients antipsychotics needs to be avoided because they can advance the progression of the disease and are associated with increased mortality.

Fronto-temporal dementia (aka Frontal lobe dementia, Pick’s Disease)

In this condition there is atrophy of the fronto-temporal region, without the histology seen in Alzheimer’s.

  • Is often more difficult to diagnose as it is typically more subtle
  • Causes personality change, and impaired social function

In some cases it may be difficult to differentiate from Alzheimer’s, but behavioural/personality change are more likely to occur early on, and things like memory and spatial awareness may be preserved for longer. There is often massive disinhibition.

Rare causes

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References

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