|

Dementia: An Overview

Last updated:

Overview

Dementia describes a progressive, irreversible decline in cognition and behavioural symptoms including memory loss, problems with reasoning and communication, personality changes, and a reduction in the person’s ability to carry out daily activities.

Most cases of dementia are degenerative or vascular. Other causes include inflammation, infection, neoplasm, toxicity, and trauma.

Dementia is not a natural part of ageing.

Definitions

To be diagnosed with dementia, there must be impairment in at least two of the following which causes a significant functional decline in usual activities/work which cannot be explained by delirium or another psychiatric disorder:

  • Memory
  • Language
  • Behaviour
  • Visuospatial function
  • Executive function

Early-onset (young-onset) dementia is dementia that develops before 65 years of age.

Mild cognitive impairment (MCI) describes cognitive impairment that does not interfere with activities of daily living and is not severe enough to be diagnosed with dementia.

Epidemiology

  • Around 7.1% of people over 65 years old in the UK have dementia
  • Prevalence is increasing overall due to increased life expectancy

Causes

Other potentially treatable causes are:

Risk Factors

Non-modifiable

  • Older age
  • Mild cognitive impairment – around 1/3 develop dementia within 3 years
  • Learning disability e.g. Down’s syndrome
  • Family history
  • Cardiovascular disease
  • Cerebrovascular disease
  • Parkinson’s disease

Modifiable

  • Lower education
  • Hypertension
  • Hearing problems
  • Smoking
  • Obesity
  • Depression
  • Low levels of physical activity
  • Diabetes mellitus
  • Low social engagement and support
  • Alcohol

Presentation

Overview

In general, features vary depending on the individual and the underlying pathology. The onset of symptoms is usually insidious, making it difficult to diagnose.

Cognitive impairment

  • Memory loss
  • Problems with communication and reasoning
  • Difficulty making decisions
  • Dysphasia
  • Difficulty with coordinated movements e.g. dressing
  • Disorientation and lack of awareness of time and place
  • Executive function impairment – difficulty with planning, judgement, initiative, and problem-solving

Behavioural and psychological symptoms

Behavioural and psychological symptoms (BPSD) tend to fluctuate and last >6 months:

  • Psychosis:
    • Delusions – these may be persecutory
    • Hallucinations – visual and auditory
  • Agitation and emotional instability
  • Depression and anxiety
    • The onset of depression in later life is a sign of dementia
  • Apathy or withdrawal
  • Disinhibition – inappropriate social or sexual behaviour
  • Motor disturbance – restlessness, wandering, repetitive activity
  • Sleep disturbance
  • Repeating phrases or questions

Difficulties with activities of daily living

In the early stages, this may be problems with carrying out household tasks and in the later stages, this may become basic tasks such as bathing, toileting, eating, and walking.

Differential Diagnoses

Alzheimer’s disease

The onset and decline of Alzheimer’s disease are slow and insidious:

  • Memory loss is usually the first symptom
  • Short-term memory is usually affected first
  • Episodic memory loss is also lost (e.g. memory loss of recent events, difficulty learning new information)

Vascular dementia

The decline in vascular dementia tends to be stepwise. Symptoms get worse in steps:

  • There may be a history of cardiovascular disease
  • Problems with gait, attention, and personality changes may be present
  • Focal neurological signs (e.g. hemiparesis, aphasia, sensory deficits) may be present

Dementia with Lewy bodies

Features alongside memory loss are present:

  • Fluctuating cognition, recurrent visual hallucinations, and problems with sleep are present
  • Features of Parkinsonism may develop as time goes on

Frontotemporal dementia

Memory and perception are relatively preserved. Features include:

  • Personality changes
  • Behavioural disturbances – such as apathy or social/sexual disinhibition

Assessment

Physical examination

Neurological signs:

  • Sensory symptoms:
  • Motor symptoms:
    • Hemiparesis
    • Tremor
    • Rigidity
    • Bradykinesia
  • Coordination abnormalities
  • Gait abnormalities
  • Visual or auditory symptoms

Cardiovascular signs:

  • Hypertension
  • Arrhythmia
  • Peripheral vascular disease

Other:

  • Psychiatric evaluation
  • Signs of physical illness e.g. head trauma

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 in the regions of the brain that are affected by dementia
  • Cerebrospinal fluid examination:
    • This involves examining for tau and amyloid which suggest Alzheimer’s disease as the aetiology of dementia

Monitoring

  • Patients with dementia should have a health or social care professional responsible for coordinating their care and having a care plan. This should be reviewed annually.
  • Patients’ physical and mental health are monitored.
  • Patients are monitored for side effects of treatments and progression of dementia.
  • Patients should have their patients reviewed regularly to reduce polypharmacy.

Patient Advice

  • Patients and carers should be educated on what the subtype of dementia is and what to expect
  • Patients should be told to inform the DVLA of their dementia diagnosis
  • Patients should be informed of the benefits of planning and consideration of a Lasting Power of Attorney, an Advance Statement, a will, and choices regarding future care and where they would like to die.
  • Patients should be informed that they may change their Advance Statements and decisions made at each care review

Complications

  • Disability and reduced ability to carry out activities of daily living
  • Dependency
  • Mobility difficulties which increase the risk of falls and fractures
  • Social isolation
  • Behavioural and psychological symptoms e.g. agitation, psychosis, apathy, aggression, sleep problems
  • Institutionalisation

Prognosis

  • Dementia is life-limiting and there is no cure
  • Lifespan after diagnosis can vary significantly, people diagnosed in their 60s-70s have a median lifespan of ~10 years but this is lowered to 3 for those diagnosed in their 90s 
  • In general, there may be 3 stages to progressive deterioration, however, this varies between individuals:
    • Early stage (mild) – years 1-2
      • Gradual, subtle features including forgetfulness, difficulties with communication, keeping track of time, and making decisions
    • Middle stage (moderate) – years 2-5
      • Limitations become more clear, more help is needed with personal care, behavioural changes
    • Late stage (severe) – year 5 and later:
      • Near-total dependence and inactivity, serious memory disturbances, unable to recognise relatives and friends, unable to eat without assistance, unaware of time and place
  • Dementia can progress more quickly following delirium

Author