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Alzheimer’s Disease

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Overview

Alzheimer’s disease is the most common cause of dementia and is characterised by progressive degeneration of the cerebral cortex leading to widespread cortical atrophy. Histologically, there are senile plaques, neurofibrillary tangles, and loss of neurones. These effects lead to progressive impairment of cognitive function.

It may be helpful to read the chapter on Dementia: An Overview.

Epidemiology

  • Alzheimer’s disease is the most common form of dementia
  • Dementia’s prevalence increases with age, with most presentations >65 years
  • Sporadic Alzheimer’s is very common, whereas familial Alzheimer’s is a very rare autosomal dominant disease with early onset

Risk Factors & Associations

Presentation

Symptoms of Alzheimer’s disease often present insidiously over 7-10 years. Symptoms in the early stages may be:

  • Lapses in memory
  • Forgetting the names of people and places
  • Difficulty finding words
  • Difficulty remembering recent events
  • Forgetting appointments

As Alzheimer’s disease progresses, symptoms become more profound:

  • Confusion
  • Difficulties with language
  • Apraxia
  • Difficulties with planning and decision making
  • Apathy
  • Wandering
  • Altered eating habits
  • Incontinence
  • Psychiatric symptoms – depression, delusions, hallucinations
  • Behavioural symptoms – disinhibition, aggression, agitation

Examination findings

Physical examination is generally unremarkable, however, features such as the following may suggest an alternate diagnosis:

  • Stepwise progression
  • Skin and hair changes
  • Parkinsonism
  • Postural instability

Differential Diagnoses

Delirium

  • Onset much more acute
  • Difficulty paying attention and fluctuating consciousness
  • Reversible causes may be present
  • Symptoms themselves fluctuate and often are worse at night
  • Short-term and varying hallucinations

Vascular dementia

  • Stepwise decline in cognitive function
  • History of cardiovascular disease/risk factors present
  • Associated temporary stroke-like symptoms may be present

Dementia with Lewy bodies

  • Progression is much faster than Alzheimer’s disease
  • Parkinsonian features e.g. tremor, shuffling gait, falls, and bradykinesia
  • Fluctuating cognition
  • Vivid hallucinations

Frontotemporal dementia

  • Onset at 50-60 years usually
  • Progression is faster than Alzheimer’s disease
  • Decreased inhibition and socially inappropriate behaviour
  • Impulsive

Parkinson’s disease dementia

Depression

  • Low mood and anhedonia
  • Memory loss may be present but is not the main presenting complaint
  • Low self-esteem

Assessment

Screening tools

Cognitive assessment tools in a non-specialist setting include:

  • 10-point Cognitive Screener (10-CS)
  • 6-item Cognitive Impairment Test (6-CIT)
  • 6-item Screener
  • Memory Impairment Screen (MIS)
  • Mini-Cog
  • Test Your Memory (TYM)

Dementia should not be ruled out solely based on a normal cognitive assessment test.

Investigations

Initial investigations in primary care

Initial investigations are to rule out possible reversible causes of symptoms:

Other investigations may need to be considered if appropriate:

  • Chest x-ray
  • ECG
  • Urine microscopy and culture
  • Urine toxicology panel for opiates, cocaine, benzodiazepine and cannabinoids
  • Syphilis serology
  • HIV testing

Referral to secondary care

If the person is severely disturbed, arrange admission to hospital. Detention under the Mental Health Act (1983) may be needed.

If dementia is suspected in people with learning disabilities arrange a specialist referral for assessment and treatment.

People with MCI are followed up regularly and referred to secondary care if their symptoms deteriorate.

All other patients should be referred to a memory assessment service for specialist assessment and management.

Investigations in secondary care

Specialist investigations involve neuroimaging to screen for reversible structural causes (e.g. subdural haematoma). These may include:

  • MRI head
  • CT head

Other specialist tests are performed to help diagnose a dementia subtype and know more about the dementia subtype and adjust management:

  • Fluorodeoxyglucose-positron emission tomography-CT (FDG-PET):
    • Shows reduced glucose uptake in regions of the brain that are affected by dementia
  • Perfusion SPECT (single-photon emission CT):
    • Shows decreased perfusion of the temporal lobes
  • Cerebrospinal fluid examination:
    • This involves examining for tau and amyloid which suggest Alzheimer’s disease as the aetiology of dementia

Management

All patients should have support with activities of daily living, optimising other comorbidities and ensuring pain is managed appropriately through person-centred care. Non-pharmacological options include:

  • Activities to promote well-being tailored to the patient’s preference
  • Group cognitive stimulation therapy
  • Group reminiscence therapy
  • Cognitive rehabilitation or occupational therapy

Pharmacological options include:

  • If mild: acetylcholinesterase (AChE) inhibitors – options are:
    • Donepezil
    • Rivastigmine
    • Galantamine
  • If moderate-severe or acetylcholinesterase inhibitor is ineffective/contraindicated: memantine
    • This is an NDMA antagonist and may be added on or used as monotherapy.

Monitoring

  • Patients should be followed up every 6 months to look for functional or cognitive declines. Home safety risks should also be assessed at these visits.

Patient Advice

  • Discussions regarding future care i.e. lasting power of attorney, advance decisions, place of death, and wills should take place with the patient and their family and carers at an early stage.
  • Patients should stop smoking, reduce alcohol consumption, and eat a healthy balanced diet to reduce the risk of dementia or further decline, and to reduce the risk of frailty
  • When communicating with patients with Alzheimer’s disease, family and carers etc. should use short and simple sentences and provide response choices to avoid confusion
  • Coping techniques should also be discussed with family and carers etc. of the patient.
  • Legal information surrounding driving should be given.

Complications

  • Institutionalisation
  • Aspiration pneumonia
    • Patients may have dysphagia to solids and liquids
    • Recurrent pneumonia may indicate terminal stages of Alzheimer’s disease and is often the cause of death
  • Dehydration
    • This is another common cause of death in Alzheimer’s disease
  • Depression
  • Falls
  • Weight loss
  • Frailty
  • Elder abuse

Prognosis

  • There is no cure or known way to prevent the progression
  • Many patients end up in institutional care

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