Dementia Now the Leading Cause of Death in Australia: Understanding Why It Is Fatal

Dementia, a term encompassing various neurodegenerative disorders characterized by a decline in cognitive functions such as memory, language, and problem-solving, has become a major health concern in Australia. While most people recognize dementia for its impact on daily life and mental functions, recent data reveal a more alarming trend: it has now overtaken other causes to become the leading cause of death in the country.

According to the Australian Institute of Health and Welfare, in 2023, approximately 17,400 Australians died directly due to dementia, accounting for about 9.5% of all deaths. Moreover, dementia often contributes to deaths indirectly, with another 15,000 fatalities where it was a significant underlying factor, leading to a combined death toll that highlights its lethal potential. Under-reporting on death certificates may mean these figures are underestimated.

So, why is dementia so deadly? The disease involves the progressive death of nerve cells within the brain. The most common form, Alzheimer’s disease, makes up 60-70% of cases and causes widespread cell loss that impairs various brain regions responsible for critical functions.

As dementia advances, individuals experience worsening symptoms, including memory loss, difficulties in communication and thinking, and changes in behavior. Importantly, the disease eventually affects the brainstem, which controls essential functions like breathing and swallowing. These impairments can directly result in death, especially when complications arise.

Secondary complications are a significant cause of mortality. For instance, difficulty swallowing can lead to aspiration pneumonia—a bacterial lung infection—which is responsible for nearly 30% of dementia-related deaths. In fact, studies suggest that pneumonia might be under-reported as a cause of death in these patients, with autopsy findings showing that nearly half of such deaths are due to respiratory infections.

Dehydration, malnutrition, and immune system weakening are common in later stages due to eating and swallowing difficulties. This makes individuals more susceptible to infections like urinary tract infections, which can progress to sepsis—a severe, body-wide response to infection that can cause organ failure and death.

Other risk factors linked to advanced dementia include impaired balance and frailty, which increase the likelihood of falls. Falls can result in fractures, hospitalizations, and fatalities. The overall decline in physical health also makes it harder for individuals to combat infections and recover from illnesses.

Age remains the most significant risk factor. The prevalence of dementia jumps sharply with age; for example, among those aged 85–89, about 1 in 5 individuals has dementia. Older adults often have comorbidities such as heart disease, diabetes, and hypertension, which can be worsened by dementia, further increasing mortality risk.

Preventive strategies focus on modifiable risk factors identified by the Lancet Commission, including low education, hearing loss, high cholesterol, depression, traumatic brain injury, physical inactivity, smoking, and social isolation. Addressing these factors through lifestyle changes and health policies could potentially prevent nearly half of all dementia cases, contributing to healthier aging.

With Australia's aging population, the number of dementia cases is projected to rise dramatically, potentially exceeding 1 million by 2065. While aging is a natural risk factor, dementia is not an inevitable part of aging, and early intervention in risk factors can reduce its incidence.

Understanding the causes and progression of dementia is crucial to improving care outcomes and preventing premature deaths. Recognizing that dementia can lead to death through both direct brain deterioration and secondary complications underscores the importance of early diagnosis, comprehensive management, and targeted preventive measures.