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Diagnosis and assessment

Residents & families GPs & clinicians 9 min read

Dementia is a clinical diagnosis built from history, examination, cognitive testing and the exclusion of other explanations. Australians wait an average of around three years from first symptoms to diagnosis 2. That delay costs people access to treatment, planning time, and the chance to make decisions while they still can.

Numbers in the text link to the 7 sources listed at the foot of this page.

The diagnostic question is not “does this person have dementia?”

It is three questions, in order. First: is there genuine cognitive decline from the person’s own previous baseline, corroborated by someone who knows them? Second: is it delirium, depression, medication effect or a metabolic problem masquerading as dementia? Third: if it is a neurodegenerative process, which one?

Skipping the second question is the most common and most consequential error. A meaningful proportion of apparent cognitive decline in older Australians is at least partly explained by something modifiable — thyroid disease, B12 or folate deficiency, uncorrected hearing or vision loss, obstructive sleep apnoea, untreated depression, alcohol, or an anticholinergic medication burden that nobody has reviewed in years.

What a proper assessment includes

This is the workup that should happen before anyone accepts a diagnostic label.

  1. Collateral history. From a spouse, adult child or long-standing carer — what changed, when, how quickly, and in what domain. Insight is often impaired, so the person’s own account is necessary but not sufficient.

  2. Cognitive testing. MMSE, MoCA, RUDAS or the GPCOG depending on the setting and the person’s background. RUDAS was developed in Australia and is less affected by education and cultural or linguistic background, which matters in a diverse RACF population 65. A single score is a snapshot; change over time is far more informative.

  3. Functional assessment. Instrumental activities of daily living — finances, medication, transport, cooking — decline before basic self-care. This is where the “interferes with everyday life” criterion is actually met or not met.

  4. Physical examination. Including gait, parkinsonism, focal neurology, cardiovascular examination, hearing and vision. Gait disturbance early in the course points towards vascular disease, normal pressure hydrocephalus or a Lewy body process.

  5. Bloods. Full blood count, electrolytes, urea and creatinine, liver function, calcium, glucose or HbA1c, thyroid function, vitamin B12 and folate. Add syphilis and HIV serology where the history warrants it.

  6. Medication review. Explicitly calculating anticholinergic burden. Nearly one in five Australian patients with dementia still carries a mean daily anticholinergic cognitive burden score of 3 or more 62.

  7. Neuroimaging. CT brain as a minimum to exclude structural causes; MRI where the presentation is atypical, young-onset, rapidly progressive, or where vascular burden and pattern of atrophy will change management.

When to refer to a specialist or memory clinic

Most straightforward late-onset dementia can be diagnosed and managed in general practice. Referral to a geriatrician, neurologist or old age psychiatrist is warranted where the presentation is young-onset (under 65), rapidly progressive, atypical in pattern, complicated by significant psychiatric symptoms, or where the diagnosis will determine access to a specific treatment.

That last point has changed. PBS subsidy for cholinesterase inhibitors and memantine has always required specialist involvement in the diagnosis 56, and the newer anti-amyloid therapies require biomarker confirmation of Alzheimer’s pathology plus specialist-led monitoring 5759 — so if disease-modifying treatment is being contemplated, specialist referral is not optional.

Blood biomarkers: real, useful, and not yet a routine GP test

Plasma phosphorylated tau 217 (p-tau217) is the most accurate blood biomarker of Alzheimer’s pathology developed to date, with diagnostic performance in specialist cohorts approaching that of amyloid PET and cerebrospinal fluid testing 73. Australian work through the Australian Dementia Network is actively examining how these assays perform in primary care, where the pre-test probability and the population differ substantially from memory clinic cohorts 73.

The honest position in September 2026 is this: these tests are transforming specialist practice and clinical trial recruitment, they are not yet a standard, universally accessible, Medicare-funded primary care investigation in Australia, and a positive result in an asymptomatic person tells you about pathology, not about whether or when that person will develop symptoms. Ordering one outside a structured pathway risks generating a result nobody can act on and a great deal of avoidable distress.

Why a diagnosis is worth having

Families sometimes ask what the point of a formal diagnosis is when there is no cure. There are several concrete answers. It gives access to Dementia Australia support services, carer supports and My Aged Care assessment. It allows enduring power of attorney, enduring guardianship and an advance care directive to be completed while the person still has capacity — which becomes impossible later. It triggers a medication review and a driving assessment. It changes how staff interpret behaviour. And it lets the person, while they can still express it, say what matters to them about how they want to be cared for.

Sources cited on this page

  1. 2 Dementia Australia. Dementia facts and figures. (Estimated 446,500 Australians living with dementia in 2026.) View source
  2. 56 Pharmaceutical Benefits Scheme. Changes to treatment phases and authority levels in medicines for the treatment of Alzheimer’s disease (effective 1 May 2023). View source
  3. 57 RACGP newsGP. Lecanemab gains TGA approval for Alzheimer’s treatment (registered 25 September 2025 for mild cognitive impairment and mild dementia due to Alzheimer’s disease). View source
  4. 59 Forward with Dementia (Australia). Update on anti-amyloid therapies — not PBS-listed; out-of-pocket cost estimated at $40,000–50,000 per year for the drug, and $80,000–100,000 per year including monitoring; MRI surveillance 3–4 times in the first six months. View source
  5. 62 Bezabhe WM, et al. Trends in anticholinergic drug exposure and associated risk factors in older Australian patients with dementia. J Psychiatr Res. 2026. (19.2% of Australian patients with dementia had a mean daily ACB score ≥3 in 2020.)
  6. 65 Guideline Adaptation Committee. Clinical Practice Guidelines and Principles of Care for People with Dementia. NHMRC-approved, 2016. An update is in development. View source
  7. 73 Australian Dementia Network (ADNeT). Blood-based biomarkers for Alzheimer’s disease in primary care. View source

See every source cited across the dementia section →

General information only, reflecting the interpretation of Umbrella Aged Care’s GPs of the published evidence as at September 2026. It is not individual medical advice, does not create a doctor–patient relationship, and must not be used to start, stop or change any treatment. Evidence and Australian regulatory and PBS arrangements change — always confirm current advice with the treating GP, pharmacist or specialist.

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