When we think of dementia, we tend to imagine it as a condition that goes hand in hand with old age. What’s not talked about is the fact the diseases that cause it have a long genesis.
Alzheimer’s Australia is holding its National Conference in Brisbane this week, providing an opportune moment to look at the state of play of dementia in Australia.
Over the last century, life expectancy in Australia has increased by around 25 years. Our ageing population is a tribute to a combination of better healthcare and nutrition, improved living conditions and education, and greater awareness of the importance of a healthy lifestyle.
The catch-22 for those living beyond their three score and ten, is that age-related degenerative disorders, such as osteoarthritis, macular degeneration and dementia, start to take their toll.
The prevalence of dementia increases exponentially with age, doubling every five years after the age of 60. Dementia affects less than 2% of 60 to 64-year-olds but more than a fifth of those aged 85 years and over.
The increase in the number of people living beyond 85 years is the main driver of the Access Economics projection that within the baby-boomer generation, there will be greater than four-fold increase in the number of dementia cases.
The number of people with dementia is expected to go from around a quarter of a million in 2010 to approximately 1.1 million cases in 2050.
What is dementia?
Dementia is an acquired decline in memory and thinking (cognition) due to brain disease, resulting in significant impairment of personal, social or occupational function.
It is not a specific disease but rather a syndrome or set of symptoms caused by many different diseases.
The most common of these is Alzheimer’s disease, which is responsible for between half and three-quarters of all dementia cases.
Less commonly, dementia can be secondary to other neurological disorders such as multiple sclerosis and Parkinson’s disease, as well as numerous systemic diseases or the effect of long-term drug and alcohol abuse.
Age-related disorders are not normal ageing: they just occur more frequently in late life although historically, “senility” was thought to be a normal part of the ageing process.
This is no longer the case, but it is important to note that there are normal age-related changes in mental function.
These changes can make it difficult to accurately detect the early stages of dementia, particularly in people over the age of 85.
There is also a syndrome called Mild Cognitive Impairment (MCI), which represents a transitional state between normal ageing and dementia. It involves mild changes in memory and other mental functions.
Around half of those with MCI will eventually develop dementia but it is difficult to predict who is at risk from a one-off assessment. Usually repeat testing after six to 12 months is required to accurately determine this.
Prospects for diagnosis
Most research into the early diagnosis of dementia has been on Alzheimer’s disease. It is known that the pathological features of this disease are present in the brain for up to 30 years before dementia develops.
For this reason, it’s really important we understand dementia is really the end stage of disease, when the brain has become sufficiently damaged for its function to be significantly affected.
Currently, there are no diagnostic tests to accurately identify individuals early in the disease process before the damage has begun and the process leading to dementia commenced.
Biomarkers, involving blood, urine, and cerebrospinal fluid, as well as brain scan tests offering this prospect, are being developed by researchers in Australia and around the world.
But, to date, none are sufficiently accurate to be used in routine clinical practice.
When the tests do become available, they will likely be first put into routine use for diagnosing MCI because a combination of clinical findings and abnormal biomarkers might eventually be sufficiently accurate to make a diagnosis before dementia is present.
New research diagnostic criteria for pre-dementia states in Alzheimer’s disease were recently released and they should facilitate research, which will be critically important if we want to prevent dementia with new treatments.
With increasing public awareness of Alzheimer’s disease, many people are presenting to memory clinics with concerns about their memory.
But many of these individuals have MCI rather than dementia. And many are disappointed because a firm diagnosis can’t be made and there’s no treatment available to definitively prevent further decline.
Currently-available drug treatments for Alzheimer’s disease and other dementias have a very limited effect and do not really alter the course of disease.
The most effective interventions at present provide information, training and support to persons with dementia and their carers through organisations such as Alzheimer’s Australia and its state branches, as well as Commonwealth-funded dementia support programs.
While there are no definitive ways of preventing dementia, there is reasonable evidence that lifestyle – physical exercise, mental stimulation, social engagement, not smoking – and certain diets associated with healthy ageing might at least delay the onset of dementia.
So the message is that if you want to enjoy your later years and as far as possible remain dementia free, adopt a healthy lifestyle as early in your life as possible.
Understanding Alzheimer’s and Other Dementias by Brian Draper (Longueville Media) is now available.