Approach to diagnosing dementia

Dementia is diagnosed when cognitive decline affects a patient’s ability to function independently and reversible causes (eg delirium or depression1) have been excluded. Components of diagnosis include:

  • a history of progressive cognitive decline2 (eg impaired new learning, apraxia, agnosia, amnesia, language disturbance, impaired executive function) affecting the patient’s ability to function independently (eg drive a car, use money, cook a meal)3, obtained from the patient or a reliable source (eg a significant other)
  • a full medical history (including drug and alcohol intake)—some drugs cause reversible cognitive impairment or delirium (see Drugs and drug groups that commonly cause or contribute to delirium); minimising the use of these drugs can reduce or reverse cognitive impairment
  • a physical examination
  • investigations
  • assessing cognition with a validated tool.

If dementia is suspected, undertake further assessment and offer referral to memory assessment specialists or services, for example aged-care assessment teams can assist with further evaluation, future care planning and implementing support services.

Discuss the diagnosis and prognosis with the patient and their significant other(s) with sensitivity and empathy; for advice on discussing bad news, see here. At the time of diagnosis, provide the patient with information about dementia, support and services; encourage them to visit the Dementia Australia website or contact the National Dementia Helpline (1800 100 500).

1 Infrequently, severely depressed patients can present with a dementia-like syndrome, known as depressive pseudodementia. These patients usually have a history of depression. Determine whether depression could be causing cognitive impairment with a detailed psychiatric assessment; see Assessing a person with depressive symptoms. If depressive pseudodementia is diagnosed, treat as for major depression. People with true dementia can also experience depression—see Depression in dementia.Return
2 Most common subtypes of dementia have a slow progression; however, vascular and frontotemporal dementias have a variety of presentations—see Typical features of common dementia subtypes.Return
3 The Dementia Outcomes Measurement Suite [URL] has a comprehensive list of tools to assess functional impairment.Return