Dementia (Overview)


The risk increases with age but is not exclusively due to the aging process:

  • 5% of >65 year olds
  • 20% of >80 year olds
  • 33% or >85 year olds

It presents a significant economic hardship- costing up to £7 billion a year- more than Cancer, heart and stroke disease combined.


Syndrome due to disease of the brain, usually chronic or progressive in nature in which there is a disturbance of multiple higher cortical (cognitive) functions including memory, thinking, orientation, comprehension, calculation, learning capacity, language and judgement; which impacts on social and/or occupational functioning (i.e. daily living).


There are many causes of dementia.  The most common is degeration of the brain parenchyma itself (Alzheimer’s; Pick’s disease; Parkinson’s Disease; Huntington’s Disease; Wilson’s disease; MS; Lewy body disease).  However, there are other causes:

  • Intracranial causes: vascular disease, tumours, trauma
  • Infective causes: CJD, neurosyphillis, TB,
  • Metabolic: Uraemia, hepatic encephalopathy, hypoglycaemia, electrolyte imbalances
  • Endocrine: hypothyroidism, hyperparathyroidism, Cushing’s and Addison’s disease
  • Vitamin deficiency: B12/folate, B1 (thiamine)
  • Toxins: prolonged alcohol misuse, heavy metals

Common Features of dementia

  • Poor memory (particularly short-term memory- e.g. repetitive questioning)
  • Language impairments, word-finding difficulty
  • Visuospatial impairment (getting lost in otherwise familiar places)
  • Loss of executive control (of complex tasks e.g. organisation of bills, planning activities)
  • Poor insight
  • May have an impaired ability to carry out activities of daily living e.g. self-care, dressing, washing etc
  • There can often be mood/behavioural changes as well as other physical manifestations e.g. weight loss, sleep disturbance

Clinical syndromes of dementia

Cortical dementia

  • Fronto-temporal (Pick’s)- characterised by prominent personality change which may manifest as a frontal lobe syndrome.  Commonly early onset dementia.  Language impairment tend to involve reduction in content (semantic anomia)
  • Postero-parietal (Alzheimer’s)- characterised by early memory loss and focal cognitive deficits (personality changes are later manifestations).  Language impairments tend to involve problems word-finding (lexical anomia)

Subcortical dementia

(e.g. Parkinson’s; huntington’s; wilson’s; small vessel vascular dementia/Binswanger’s dementia; normal pressure hydrocephalus)- characterised by gross psychomotor slowing, depression, movement disorders, mild amnesia and personality changes

Mixed (e.g. Lewy body dementia)

Multifocal (e.g. CJD)


  • Take a full history with the patient and, ideally, a relative or close friend
    • Cognitive decline in dementia is progressive and non-fluctuating, usually slowly
      • A rapid decline may suggest a reversible cause (more likely a delirium) e.g. a tumour, metabolic cause (B12/folate deficiency), medication related, alcohol
        • NB A rapid decline may also feature in vascular dementia
  • A mental state examination is useful to look for signs of mood/behavioural disorders
    • Note in depression, the patient may have insight into the memory problems, they may be distressed by it.  They may also be able to remember things with cues.  There may also be a past history of depression.
    • Note that depression and dementia can co-exist.  It is important to treat the depression and continue to assess the dementia.
  • Cognitive testing
    • Initially, an MMSE can serve as a good measurement for a baseline (it is not diagnostic of dementia/delirium)
      • Serial testing is required to suggest dementia
    • Addenbrooke’s assessment of cognition is commonly used as a more formal test in specialist assessments


  • A full workup should be done to exclude reversible causes
    • Bloods
      • FBC, U&Es (inc Ca), Vit B12 and folate, TFTs, glucose, serology for syphilis/HIV (if appropriate)
    • CXR, ECG, urinalysis
    • Imaging (not required in all cases- but particularly needed where there is a rapid decline, in younger individuals, if there is focal neurological signs/symptoms, or if the patient is at risk of pathology e.g. fall with warfarin)
      • CT head
      • MRI head


  • A diagnosis of dementia (of any cause) can be made according to criteria set out jointly by NINCDS and ADRDA groups
  • The criteria for all-cause dementia are
    • Cognitive or behavioural symptoms that:
      • Interfere with the ability to function at work/with usual activities (note if this is not the case, the diagnosis is more likely to be a mild cognitive impairment which may, or may not, progress) AND
      • Represent a decline from previous levels of functioning AND
      • Are not explained by a delirium or major psychiatric disorder
      • Furthermore cognitive testing should reveal 2 or more of
        • Impaired ability to acquire/remember new information
        • Impaired reasoning and handling of complex tasks
        • Impaired visuospatial ability
        • Impaired language function
        • Changes in personality or behaviour
  • Note specific criteria have been suggested for diagnosing the specific subtypes of dementia (see individual posts)


  • The management of dementia is largely supportive and educational e.g.
    • Simplifying medication regimes; simple memory aids e.g. calendars, alarms etc; encouraging social interaction; ensuring safe environments (ideally at home); supporting caregivers etc
  • Pharmacological management is usually reserved for moderate Alzheimer’s/mixed dementia and only slows down the progression of the disease (see Alzheimer’s)

Other issues

  • Driving and dementia- at some point there will be a time when the patient will no longer be safe to drive.  Discussions about driving should be had earlier on in the disease in order to safely assess and recommend as to whether a patient should be driving.
  • Patient/carer safety
    • There may be an increased risk of falls, wandering, aggression, abuse, neglect etc
    • All should be considered and the risks reduced where possible (again, keeping a patient in their own home is often better if possible)
    • A full discussion with the patient and their family/carers is important

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