In 2024, the Australian Institute of Health and Welfare estimated that there were 425,000 Australians living with dementia.
Dementia is an umbrella term used to describe a group of conditions that affect brain function and interfere with a person’s ability to carry out everyday activities. Of these, Alzheimer’s disease is the most common, accounting for around two-thirds of all cases.
You’ve likely heard of Alzheimer’s, maybe even known someone who has been affected by it. For many people it is a disease synonymous with memory loss, confusion and a gradual decline in independence. Yet despite widespread awareness of the condition, much remains unknown about how and why Alzheimer’s disease develops, and whether there is anything we can do to prevent it.
Researchers such as Professor Ralph Martins have spent decades working to better understand the biological changes that occur within the brain, often years before symptoms manifest. Their discoveries are helping to reshape how scientists think about diagnosis, treatment and ultimately, the steps we can take to reduce the impact of the disease.
What Is Alzheimer's disease?
Alzheimer's disease is a progressive neurodegenerative disorder that is characterised by the accumulation of a protein called beta-amyloid. In healthy individuals, beta-amyloid is naturally occurring and typically cleared away by the body. In people with Alzheimer’s, the protein can build up and clump together, forming sticky amyloid plaques.
These plaques contribute to inflammation, damage to nerve cells and the aggregation of another protein called tau. Over time, these processes disrupt communication between brain cells and contribute to the gradual loss of brain tissue.
As different regions of the brain become affected, the functions they control begin to decline. While memory impairment is often one of the earliest signs, Alzheimer’s can also impact language, judgement, decision-making, mood and behaviour as it advances.
Why symptoms can take decades to appear
The significant finding that biological changes associated with Alzheimer’s can be detected 10-20 years before cognitive decline becomes noticeable is catalysing research in this area.
Neuroplasticity - the brain’s ability to adapt - enables healthy neural networks to compensate for early damage by strengthening existing connections and recruiting alternate pathways. The resultant symptomatic delay means by the time signs of the disease become evident; it has often already developed considerably, and thus a major shift in Alzheimer’s research has occurred, with efforts focused on the development of tools enabling early detection.
How is Alzheimer's disease diagnosed?
Identifying and diagnosing Alzheimer’s disease remains one of the greatest challenges in dementia care and research today. Clinical assessment and cognitive testing, together with brain imaging, remain important diagnostic tools but continue to have their challenges. Because symptoms can overlap with other forms of dementia and neurological conditions, achieving a definitive diagnosis can be arduous, with many testing methods proving expensive or inconclusive.
This has led to growing interest in biomarkers – measurable biological indicators that can aid in early detection and screening. These biomarkers may be identified through brain imaging, spinal fluid analysis and, more recently, blood testing, an area of research that Professor Martins and his colleagues continue to explore.
Emerging blood tests capable of detecting biomarkers in circulation that correlate closely with beta-amyloid build-up in the brain are becoming increasingly available. The implications of developing minimally invasive and cost-effective diagnostic tools are enormous.
By enabling earlier and more accessible screening, these tests have the potential to transform Alzheimer’s detection at a population level. Professor Martins believes blood-based biomarkers may one day be used in a similar way to PSA testing for prostate cancer, helping identify individuals at increased risk and creating new opportunities for monitoring, intervention and research participation. Whilst testing is already available in parts of the United States, Professor Martins and his team are working towards a future where these advances are accessible and affordable for all Australians.
Alongside efforts to detect Alzheimer's disease earlier, researchers are also working to better understand who may be at greater risk of developing the condition in the first place.
The Apolipoprotein E (APOE) gene has been identified as an important risk factor for Alzheimer's disease, with individuals carrying the APOE ε4 variant known to be at increased risk. Whilst this does not guarantee they will develop the disease, knowledge of genetic risk factors may help identify those who could benefit from closer monitoring, earlier screening and targeted lifestyle interventions aimed at supporting long-term brain health.
Looking ahead
Our understanding of Alzheimer's disease has advanced dramatically over the past several decades. What was once viewed primarily as an inevitable consequence of ageing is now recognised as a complex biological disease that begins many years before symptoms emerge.
Through advances in genetics, biomarker research and early detection technologies, researchers are gaining an increasingly detailed picture of how Alzheimer's develops and how it may one day be identified earlier and managed more effectively.
While many questions remain unanswered, the work of researchers such as Professor Ralph Martins continues to provide reason for optimism. Each new insight brings us closer to reducing the impact of Alzheimer's disease on individuals, families and communities nationwide.
Professor Ralph Martins is an internationally recognised Alzheimer's disease researcher whose work focuses on dementia prevention, early diagnosis, healthy ageing and brain health. This article was developed in conversation with Professor Martins as part of the Research Insights series.
