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Assessment and diagnosis of dementia

Diagnostic criteria, assessment and screening tools, and guidance on disclosing diagnosis.

Diagnostic criteria for cognitive impairment and dementia

Dementia is the umbrella term for a number of neurological conditions, of which the major symptom is the decline in brain function due to physical changes in the brain. It is distinct from mental illness.

Dementia is categorised as a Neurocognitive Disorder (NCD) in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The NCD category is then further subdivided into Minor NCD and Major NCD. The term “cognitive” refers to thinking and related processes, and the term “neurocognitive” has been applied to these disorders to emphasise that brain disease and disrupted brain function lead to symptoms of NCD.

The NCD category encompasses the group of disorders in which the primary clinical deficit is in cognitive function, which is acquired rather than developmental. Impairment may occur in attention, planning, inhibition, learning, memory, language, visual perception, spatial skills, social skills or other cognitive functions.

Minor neurocognitive disorder

In DSM-5, a minor neurocognitive disorder is also medically referred to as Prodromal Disease or Mild Cognitive Disorder (MCI) and is defined by the following criteria:

  • There is evidence of modest cognitive decline from a previous level of performance in one or more of the domains listed below, based on the concerns of the individual, a knowledgeable informant or the clinician; and a decline in neurocognitive performance, typically involving test performance in the range of one and two standard deviations below appropriate norms (i.e. between the third and sixteenth percentiles) on formal testing or equivalent clinical evaluation.
  • The cognitive deficits are insufficient to interfere with independence (for example instrumental activities of daily living such as complex tasks such as paying bills or managing medications, are preserved), but greater effort, compensatory strategies, or accommodation may be required to maintain independence.
  • The cognitive deficits do not occur exclusively in the context of a delirium.
  • The cognitive deficits are not primarily attributable to another mental disorder (for example major depressive disorder and schizophrenia).

Major neurocognitive disorder

In DSM-5, a major neurocognitive disorder is defined by the following:

  • There is evidence of substantial cognitive decline from a previous level of performance in one or more of the domains listed below, based on the concerns of the individual, a knowledgeable informant, or the clinician; and a decline in neurocognitive performance, typically involving test performance in the range of two or more standard deviations below appropriate norms (i.e. below the third percentile) on formal testing or equivalent clinical evaluation.
  • The cognitive deficits are sufficient to interfere with independence (i.e. requiring minimal assistance with instrumental activities of daily living).
  • The cognitive deficits do not occur exclusively in the context of a delirium.
  • The cognitive deficits are not primarily attributable to another mental disorder (for example major depressive disorder and schizophrenia).

Cognitive domains

The DSM-5 details six cognitive domains which may be affected in both Minor and Major NCD:

Complex attention

Involves sustained attention, divided attention, selective attention and information processing speed

Warning signs - Patient has increased difficulty in environments with multiple stimuli (TV, radio, conversation). Has difficulty holding new information in mind (recalling phone numbers or addresses just given or reporting what was just said)

Executive function

Involves planning, decision making, working memory, responding to feedback, error correction, overriding habits and mental flexibility

Warning signs:

  • Patient is unable to perform both familiar and complex tasks and projects (at work and at home).
  • Needs to rely on others to plan instrumental activities of daily living or make decisions.
  • Has problems with abstract thinking, displays loss of initiative as well as poor/decreased judgement.

Learning and memory

Involves immediate memory, recent memory (free recall, cued recall and recognition memory) and long term memory

Warning signs:

  • Patient repeats self in conversation, often with the same conversation.
  • Cannot keep track of short list of items when shopping or of plans for the day.
  • Requires frequent reminders to orient task at hand, confusion about time and place, and repetitive behaviour.


Involves expressive language (naming, fluency, grammar and syntax) and receptive language

Warning signs:

  • Patient has significant difficulties with expressive or receptive language.
  • Often uses general terms such as 'that thing' and 'you know what I mean'.
  • With severe impairment may not recall names of closer friends and family.

Perceptual-motor function

Involves picking up the telephone, handwriting, using a fork/spoon

Warning signs:

  • Patient has significant difficulties with previously familiar activities (using tools or, driving a motor vehicle) and navigating in familiar environments.

Social cognition

Involves recognition of emotions and behavioural regulation, social appropriateness in terms of dress, grooming and topics of conversation

Warning signs:

  • Patient may have changes in behaviour (shows insensitivity to social standards, or make decisions without regard to safety).
  • Patient usually has little insight into these changes. Becomes socially withdrawn or isolated.

ICD-11 coding for dementia

The International Classification of Diseases (ICD) is the standard diagnostic tool for epidemiology, health management and clinical purposes. You can find ICD-11 codes on the World Health Organisation’s ICD website.

Assessment for cognitive impairment and dementia

There is no single definitive test for diagnosing dementia. Assessment will account for behavioural, functional and psychosocial changes, together with radiological and laboratory tests. The assessment process may take three to six months.

Assess cognition if you have any indication or suspicion of impairment in your patient. This is the first step in determining whether or not your patient needs further evaluation.

Take notes about the history of the patient from an “informant”: someone who knows the patient well and has observed their cognition and function over time. They might be a partner, family member or close friend.

You could ask the informant about the following in relation to your patient:

  • risk factors: vascular disease, alcohol, head injury, mood disorders, behavioural and psychological symptoms, recent illness, medications
  • Activities of Daily Living (ADL), instrumental ADLs, cognitive complaints, mood, driving, safety
  • behavioural changes and functional decline (time course = onset, progression)

One useful tool for interviewing informants is the AD8 Dementia Screening Instrument.

The following cognitive assessment tests are the most commonly used; however, it is important to choose the tests most suitable for your patient and for the health setting within which you work.

Screening for cognitive impairment and dementia

There are several opportunities in the practice to screen your patients for possible cognitive impairment and dementia. These include:

The 45+ Health Check

  • An opportunity to pick up younger onset dementia in your patients under 65 years of age
  • Build in questions about cognitive function, concerns about memory, mood and behaviour
  • Look at possible risk factors for dementia (modifiable and non-modifiable in your patient)
  • Can be charged to MBS item #717

The 75+ Health Check

  • An opportunity to pick up possible cognitive impairment and dementia in your patient
  • Modify the existing 75+ Health Check and include questions about cognitive function, memory, frailty, dexterity, driving and advanced care planning
  • Can be charged to MBS item #705

The Chronic Disease Management/ Plan

  • An opportunity to screen for possible cognitive impairment - in your patients under 65 years of age as well as over 75 years of age- undertake annually or bi-annually
  • Can be charged to MBS item:
    • #721 (development of plan)
    • #732 (review of plan)
    • #723 (a Team Care Arrangement)
    • #731 (a plan developed for patients in residential aged care)
    • #10997 (practice nurse monitoring and support as part of plan).

Mental Health Treatment Plan (MHTP)

  • An opportunity to be mindful of a possible diagnosis of dementia/cognitive impairment when preparing and reviewing a MHTP for your patient
  • N.B. Dementia is not classified as a mental health disorder under the Better Access to Mental Health Scheme (hence, MBS items cannot be charged)

For more information, visit the Medicare Benefits Schedule website.

Screening notes

  • If uncertain or inconclusive, repeat tests over time
  • Use sensitive language when introducing the tests/assessment process to your patients and their families/carers
  • Be prepared for questions from your patient or their families and carers. For example:
    • What tests will be conducted?
    • Who will be performing the tests and how long will it take?
    • Should I prepare for the tests in any way?
    • Will any of the tests involve pain or discomfort?
    • Will there be any cost involved?
    • What follow-up will be necessary and who will follow up?
    • How will I be informed of the test results and the diagnosis?

Other diagnostic tests

Mental state and physical examination

  • Differential diagnosis: look for specific conditions that mimic dementia (depressive disorder, delirium and drug/dosing interactions), or that can exacerbate dementia (e.g. cardiac failure, use of anticholinergic drugs).
  • Check nutrition, hygiene, visual or hearing impairment.

Blood, urine tests and imaging

  • Urinary tract and other infections
  • Renal and liver (hepatic) function
  • Rule out rare but reversible causes for example abnormal thyroid function, calcium or Vitamin B12 deficiency, electrolyte balance (salt and water), tumour

The following investigations are usual practice: FBE, EUC, LFTs, Ca, TFT, B12, Folate, MSU, ECG, and if indicated, VDRL, CXR, HIV.

Imaging recommended: CT brain, MRI, and if indicated, PET, SPECT, FRMI.

Assessment for Behaviour and Psychological Symptoms of Dementia (BPSD)

Almost all patients with dementia experience BPSD; these are also referred to as neuropsychiatric, non-cognitive symptoms. The symptoms vary between patients and over time and can include:

  • Mood disturbances (anxiety, apathy, depression, euphoria)
  • Hyperactivity-type symptoms (aberrant motor behaviour, aggression, agitation, disinhibition, irritability, restlessness)
  • Psychotic symptoms (delusions, hallucinations, paranoia)
  • Other behavioural symptoms (changes in appetite, hoarding, night-time behaviour disturbances, wandering)

These symptoms become more common as the dementia progresses and present a major cause of stress to carers.

When BPSD occur, assess factors that may cause, aggravate or reduce the behaviour. Assessment should first exclude physical causes, such as delirium (common in patients with dementia), urinary tract infections or a drug interaction. Other factors, such as the environment and behaviours of others, should also be considered.

The assessment should ideally consider:

  • Frequency of behaviour over time
  • Context and consequences of the behaviour
  • Mental health
  • Physical health
  • Medication side effects
  • Previous habits and beliefs
  • Psychosocial factors
  • Factors in physical environment
  • Possible undetected pain or discomfort

For more information about BPSD assessment and clinical support services for your patients, visit the Dementia Behaviour Management Advisory Services (DBMAS) website.

Communicating the diagnosis

Providing a diagnosis to a person with dementia is fundamental to the principal of personal autonomy and it should be expected. Your role in disclosing the diagnosis is of paramount importance.

Receiving a diagnosis of dementia has an enormous impact on the person with dementia, their carers and families. Following a diagnosis, patients often report feelings of loss, anger, uncertainty and frustration. Others report feelings of relief to have an explanation for their symptoms.

Although a very small number of people may choose not to know the diagnosis (and this should be discussed during the assessment process), the majority of people want to be informed, so it is important that health professionals are honest and truthful when communicating the diagnosis to the person with dementia.

Recommendations for disclosing a diagnosis

  • Discussion of the diagnosis and its consequences may occur over time or over multiple practice visits, but disclosure should occur as early as practicable.
  • Be clear and respectful when communicating a diagnosis to the person with dementia and families and carers.
  • The conversation should occur within the context of the wishes of the person with dementia (in a patient-centred approach), their relationship with the medical practitioner providing the diagnosis and the primary purpose for their consultation.
  • The diagnosis of dementia should come after discussions about memory and thinking difficulties. Medical practitioners should discuss the possibility of dementia as a diagnosis during the process of assessment (which may take three to six months).
  • Provide information about dementia in a clear manner. Highlight that progression of dementia is often slow, symptomatic treatments are available and that research is striving to find cures and better treatments.
  • Be aware of your patient’s history of depression and/or self-harm. This news may prove to be particularly challenging especially following the first few months of the diagnosis. Counselling should be offered in these cases as an additional form of support.
  • Be aware of the particular issues in communicating a diagnosis to patients from culturally and linguistically diverse (CALD) backgrounds. The term dementia may be interpreted as offensive and disrespectful in some cultures.
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Last updated
15 December 2023