The tangled webs our brains can weave

The National Health and Medical Research Council (NHMRC), and the Australian Research Council (ARC), have recently announced joint funding totalling more than $81 million to support dementia research. A small comfort perhaps to those already affected by the disease, but a critical step towards prevention and a cure. Dementia is not actually one, specific illness. Rather, the term ‘dementia’ encompasses a range of neurocognitive disorders that can cause changes in personality, cognitive function and behaviour. Depending on the severity of the neurocognitive disorder, symptoms range from what can appear to be an accelerated cognitive aging process – such as forgetfulness or lapses of attention – through to major impairments in functioning that prohibit independent living. Neurocognitive disorders have their own classification category in the Diagnostic and Statistical Manual of Mental Disorders (the DSM). For those of you that might find the idea of dementia as a mental illness confronting, don’t let this change the way you think about dementia, let it change the way you think about mental illness. It might help to consider the story of the first recorded case of Alzheimer’s disease. In 1906, Dr Alois Alzheimer reported the case of a female psychiatric patient, the eerily named ‘Auguste D’, who had been admitted to a psychiatric unit with symptoms including substantial memory loss, hallucinations, and an inability to speak. After her untimely death five years after admission, aged 51 years, an autopsy revealed what we now know to be tell tale signs of Alzheimer’s disease; sticky plaque lodged between nerve cells (beta- amyloid plaques), and neurons twisted like tangled threads (neurofibrillary tangles). Dr Alzheimer’s findings, though considered underwhelming at the time, are now recognised as a landmark moment for our understanding of neurocognitive disorder, and the relationship between the brain and behaviour. Over a century later and we are still untangling the mystery of neurocognitive disorder. Worldwide, 44 million people are estimated to be living with dementia. Recent estimates show 330,000 Australians are affected, including one in 10 Australians over 65. The rate of dementia is predicted to rise significantly over the next 30 years. Even more worrying, a recent study found that the prevalence of dementia could be up to three times higher for individuals aged 60 years or older and of Aboriginal or Torres Strait Islander descent, compared to the national population average. The most significant risk factor for dementia is growing old. This one is difficult to avoid. But, there are some risk factors for dementia that are modifiable. While Dr Alzheimer’s case of August D. demonstrates how changes in the brain can lead to changes in behaviour, there is also solid evidence that changes in behaviour can lead to changes in the brain. For example, smoking, heavy drinking, and a sedentary lifestyle have all been associated with an increased risk of cognitive decline and neurocognitive disorder. No surprises there. The modification of other behavioural or lifestyle risk factors is more complicated though. For example, there is evidence for a relationship between dementia incidence and access to secondary and tertiary education. For some people, access to secondary or tertiary education is not necessarily modifiable, and may depend on a range of other variables that can also influence health outcomes, like socio- economic status or geographic location. And of course, there is the role of genetics. There are certain genes that can be passed on which increase the risk of developing dementia. There is also evidence that an inherited genetic mutation can cause certain kinds of dementia, such as the aptly named Familial Alzheimer’s Disease. On the flipside, dementia can occur randomly, with no immediate family history to note. In all likelihood the onset of neurocognitive disorder is the result of complicated interactions between a genetic predisposition, lifestyle factors, environmental conditions, and an individual’s unique degree of exposure to each of these risk factors – which is of course confounded by age. After hearing all of that, aren’t you relieved that at least $81 million is being spent on the prevention and cure of this perplexing and devastating illness? Don’t you wish it were more? Dementia is likely to affect all of us, directly or indirectly, sooner or later. It is a public health issue, a social issue, an economic issue, an equity issue and a timely addition to Australia’s research agenda.