The apparent and real growth of dementia

I mentioned dementia and Alzheimer’s disease in a recent essay, and there followed a debate in the Comments about whether you die from or with Alzheimer’s, and whether, when you’re very old, you just die. It was a good discussion, and I felt I ought to do some more work on the question. That led me to go back to the causes of death, about which I have been interested for a long time. The long-term trend in mortality offers us insights into the journey of our society. I’ll get back to dementia in due course, but first comes a rather long excursion into how we know what we know (or what we think we know). For all this I rely mostly on the ABS and the Australian Institute of Health and Welfare (AIHW), both of which publish most useful material.

The Australian colonies began to collect statistics on the causes of death in the 1850s, but it was not until 1907 that the then Commonwealth Bureau of Census and Statistics began to organise the resulting data in a systematic national way. Because of the growth of knowledge, there were nine revisions to the way we do this in the 20th century (a tenth occurred in 2015), in the form of changes to the International Statistical Classification of Diseases and Related Health Problems, usually shortened to ICD. The ICD can trace its origins to Florence Nightingale, and began its official existence in 1900 at an international conference. In 1907 the ICD offered 189 causes of death; there were around 2850 in the ICD of 2000. They are all based on what the doctor writes on the death certificate, and he or she is expected to state not only the cause of the death, but also to provide an indication of any associated conditions believed to have contributed to the death. The growth in knowledge makes it very hard to talk about long-term trends with respect to particular diseases, but the experts have done their best.

As I have said elsewhere, many times, the general story is an astonishing one of almost continuous improvement. We now  live much longer, and in almost every case the causes of death are less powerful than any of them was a century ago. Young children used to die of diarrhoea; now they almost never do. At the beginning of the 20th century a quarter of all deaths were of children from 0 to 4. Today they account for between one and two per cent of all deaths. That we all are likely to live much longer can be seen in the following ABS graph.

In the 1880s the average life expectancy of a boy baby was about 45 years; for a girl baby about fifty years. Today, or rather a few years ago, those numbers have been replaced by 80 and 85 respectively. I saw somewhere a statement that one in three girl babies born today could expect to reach 100 years. It’s not only the great improvement in infant mortality that is the cause. Our increasing wealth and the growth in the process of educating everybody as far as possible have led to improvements in understanding, in food, water quality, sanitation, in a marked decline in tobacco use, and so on. Yes, I am aware of obesity. All apparent improvements come with cost of some kind, often costs that were simply not anticipated. Deaths from injuries of all kinds (including road crashes, drownings, electrification and poisonings) run at about half the rate of a century ago. Tuberculosis is a thing of the past, but it was a killer, and for that reason the favourite death on stage for women in opera. Deaths from infections of all kinds, one in eight deaths in 1900, have almost disappeared. Despite the current media focus on suicide, the rates have been pretty constant for a century and more.

What is plain is that our population is getting relatively older. Part of the cause is that we just live longer. The other major part is that Australians are having fewer babies, which means a smaller proportion of Australians between 20 and 50 than was the case in the 1960s and 1970s. We hear a lot about that distribution from Treasurers worried about who is going to do all the work to bring in the tax revenues needed to look after the elderly. As we get older we are more likely to suffer from diseases that affect older people more than younger ones, such as the circulatory diseases — heart attack, angina, stroke, high blood pressure and so on. But as deaths from such ailments have declined, cancers are now no less important among older Australians. One saving grace is that in older people some cancers may grow only slowly, meaning that you might die with a cancer, but not from it. Nonetheless, the death-rate from cancer among older Australians has increased over the century, because of the decline of the other causes. The older we get, the more likely we are to contract a cancer.

In 1907 ‘senility’ was the fourth largest cause of death, but as the years passed it became unfashionable as well as unscientific to specify such a cause, and by the late 1960s it had passed from the ICD. One can only assume that in those days ‘senility’ included at least what we would now call any of the hundred forms of dementia. In any case, dementia is now a cause, but because of the difficulty of untangling the old ‘senility’ category, the relevant data now start from 1968, not from 1907. Dementia is included in ICD as a ‘nervous system’ disease, a category that also includes Parkinson’s disease, motor neurone disease, epilepsy, encephalitis and meningitis. None of these is a big killer, but the AIHW made special mention of the category because rates of death are increasing. This is especially the case with Alzheimer’s, the death-rate for which doubled from 1980 to 2000, while ‘age-standardised Alzheimer rates rose from 0.8 deaths per 100,000 for males to 6.6 for males and from 0.4 to 9.2 for females’. That is a really big jump, even if the numbers are small. The great majority of the deaths are in the older age-groups.

The core problem, as Alzheimer’s Australia has pointed out, is that because our population is growing older and older more Australians are, in default of a miraculous breakthrough, going to encounter dementia in the years ahead, either as sufferers or as carers. The estimate for 2016 is that about 350,000 Australians have dementia; in five years time the number will be 400,000, and likely to be much more than double that in 2050. Three in ten over the age of 85 and one in ten over the age of 65 now have dementia. It is the single biggest cause of disability for those over 65.

What can we do about it? Not very much, other than learning how to manage with it. Dementia is the global term used to describe the symptoms of illnesses that cause a progressive decline in a person’s functioning, especially to describe a loss of memory, intellect, rationality, social skills and physical functioning. It is a cruel disease which, unlike many others, creeps up on you slowly and deprives you of the mental wherewithal to deal with it. Every person with dementia needs a carer, and later, more carers. Yet the sufferer, at least in the beginning, is the same person that you have known for a long time. He or she is having trouble telling you what is happening, what today is, what is on the daily calendar, what happened yesterday. I have some experience with the other major diseases: in my experience dementia has no real parallel.

Yes, we are putting a lot money into ‘combatting’ dementia, about $60 million a year for the next few years. It doesn’t go far, and in my judgment we are only at the beginning of serious engagement with the research that will lead to a decline in the death-rate, the morbidity and the need for carers (caring can grow to be almost a full-time occupation). To end on a brighter note, the story of the changes in mortality I have summarised in this essay should give us hope, at least in the long term.

Endnote: All the data that relate to mortality are assembled by the AIHW in what is called the General Record of Incidence of Mortality, whose acronym is, of course, GRIM. Someone had a sense of humour!

For any reader who would like to explore these matters further, I would recommend a fine summary of the 20th century story of mortality by AIHW, and the website of Alzheimer’s Australia.

I should declare an interest. My father and my mother-in-law both suffered from dementia in their final years, and I am presently the Patron and Ambassador of Alzheimer’s Australia ACT.