Mental disorders are traditionally seen as rather like flowering bulbs. Above the ground we see their symptoms, but we know their source lies hidden beneath the surface. If we treat the symptoms without addressing the cause – cut off the flower without uprooting the bulb – they will just flower again later.
The idea that each mental disorder has an underlying cause is itself deeply rooted. We imagine that underneath the clinical symptoms of schizophrenia or depression there is an underlying disease entity. If treatment is to be effective and lasting rather than merely symptomatic it must target that concealed origin.
People have had many ideas about the form the unseen cause might take. Medieval physicians imagined a “stone of folly” that had to be surgically removed from a mad person’s head before sanity could prevail. Funnily enough, the best known painting of such an operation, Hieronymus Bosch’s The extraction of the stone of madness, shows the “stone” to be a flower bulb.
More recently, psychiatrists often suppose the hidden cause is neural, such as a brain disease or chemical imbalance. Psychologists sometimes prefer to invoke specific cognitive malfunctions or conflicts. What unifies them is the idea that a cluster of symptoms can be traced back to an underlying pathology.
This way of thinking makes perfect sense in some areas of medicine. A collection of bodily symptoms often points to an underlying disease process. Scarlet fever is revealed by a bright red rash, fever and a sore throat, all caused by an underlying bacterial infection. It would be folly to treat it symptomatically. Pacifying the rash with wet towels, taming the fever with aspirin and drinking tea with honey to soothe the throat would not attack the hidden, microbial cause.
Unfortunately mental disorder is not like infectious disease. Rarely is there a single, identifiable cause underlying a group of symptoms. Most psychiatric symptoms spring from a tangled multiplicity of causes. In addition, many symptoms are not specific to a single condition.
Billions of research dollars have been spent trying to locate the unique hidden cause of each mental disorder. The results have been spectacularly disappointing, not because mental health researchers are inept but because the causes of mental disorder are extremely complex.
To extend the botanical metaphor, mental disorders are less like flowering bulbs than like bamboo. An interconnected network of underground roots (hidden causes) generates many visible stems (symptoms). No stem can be traced back to a single root, and no root feeds a single stem.
The network approach to mental disorder
If there is no one-to-one link between symptoms and hidden causes, maybe we are better off putting aside the search for those causes. A new way of thinking about mental disorder argues just that, proposing that we focus full attention on symptoms instead.
Rather than seeing symptoms as manifestations of hidden disease entities – as the tip of an iceberg – this “network approach” tells us to examine how symptoms relate to one another. It argues the symptoms of a disorder cluster together not because they share a hidden cause but because they interact with and potentially reinforce one another.
The network approach to mental disorder, developed by Dutch psychologists Denny Borsboom, Angelique Cramer and colleagues, represents each symptom as a node in network. It draws links between these nodes to reveal the symptoms that are most strongly related, such as which ones influence other symptoms most powerfully and extensively.
For example, loss of appetite and weight loss are both symptoms of major depression. If researchers found they were closely related, and appetite loss drives weight loss, then an arrow would be drawn from the former to the latter. By this means a group of dynamically related symptoms can be represented by a network diagram.
Several features of the resulting networks are particularly interesting. Certain symptoms can be shown to be central, related to many others, whereas others are more peripheral. Certain symptoms primarily cause others, whereas some symptoms are primarily caused by others.
Because mental disorders are seen as mutually reinforcing symptoms, clinicians should target central symptoms that cause many others. Successfully treating these symptoms should have broadly beneficial effects. It should reduce other existing symptoms and prevent the spread to new symptoms.
Certain symptoms may also be bridges from one disorder network to another. For example, sleep disturbance among people with post-traumatic stress disorder (PTSD) may cause fatigue, and fatigue may serve as a bridge to the depression network by activating concentration problems and guilt.
Researchers have carried out network analyses of several disorders, using similar computational tools as those used in social network analysis, an approach to mapping relations among people. One study of several substance use problems showed that using the substance more than planned was usually the most central symptom. It was strongly related to having worse withdrawal symptoms and needing more of the substance to get the same effect (“tolerance”).
Several studies have explored anxiety disorders. A study of social anxiety showed that avoidance of potentially threatening social situations was a central symptom and thus a prime target for treatment. Research on PTSD following a catastrophic earthquake in China showed that sleep difficulty and hypervigilance for future threats had especially potent influences on other symptoms.
Turning to depression, a study of short term fluctuations in symptoms revealed the centrality of loss of pleasure in the symptom network. It activated an assortment of other symptoms including sadness, loss of energy and interest in activities and irritability. In contrast, sadness, crying and a loss of interest in sex were incidental.
Another study showed that depressed people whose symptoms were more densely connected were more likely to have persistent depression two years later. This finding accords with the network view that symptoms of mental disorders can be self-reinforcing. People whose symptom networks form a tighter web may therefore have greater difficulty overcoming their problems.
The network approach has several important implications. For researchers, it suggests that the search for single causes of mental disorders is quixotic. Of course, symptoms have an assortment of social and neurobiological sources, but these sources are highly unlikely to be unique to one condition.
For practising psychiatrists and psychologists the network view implies that symptoms should be taken seriously in their own right and not seen merely as pale manifestations of underlying disease. Treatments should directly target particular symptoms, not a fictitious hidden cause.
Boorsboom and Cramer make this point amusingly in regard to major depression.
If [depression] does not exist as an entity that exists independently of its symptoms (like a tumour does), attempting to treat it analogous to the way medical conditions are treated (cutting away the tumour) is like trying to saddle a unicorn.
The network approach also has a strong message for all of us who care about mental health and illness. We should abandon the last vestiges of our belief that mental disorders are best seen as medical diseases. The symptoms of depression, PTSD, or social anxiety don’t point to an underlying disorder. They are the disorder.
Evidence gathered over 60 years about adding fluoride to drinking water has failed to convince some people this major public health initiative is not only safe but helps to prevent tooth decay.
Myths about fluoridated water persist. These include fluoride isn’t natural, adding it to our water supplies doesn’t prevent tooth decay and it causes conditions ranging from cancer to Down syndrome.
Now the National Health and Medical Research Council (NHMRC) is in the process of updating its evidence on the impact of fluoridated water on human health since it last issued a statement on the topic in 2007.
Its draft findings and recommendations are clear cut:
NHMRC strongly recommends community water fluoridation as a safe, effective and ethical way to help reduce tooth decay across the population.
Here are four common myths the evidence says are wrong.
1. Fluoride isn’t natural
Fluoride is a naturally occurring substance found in rocks that leaches into groundwater; it’s also found in surface water. The natural level of fluoride in the water varies depending on the type of water (groundwater or surface) and the type of rocks and minerals it’s in contact with.
There are many places in Australia where fluoride occurs naturally in the water supply at optimum levels to maintain good dental health. For example, both Portland and Port Fairy in Victoria have naturally occurring fluoride in their water at 0.7-1.0 parts per million.
The type of fluoride commonly found in many rocks and the source of the naturally occurring fluoride ion in water supplies is calcium fluoride.
The three main fluoride compounds generally used to fluoridate water are: sodium fluoride, hydrofluorosilicic acid (hexafluorosilicic acid) and sodium silicofluoride. All these fully mix (dissociate) in water, resulting in the availability of fluoride ions to prevent tooth decay.
So regardless of the original compound source, the end result is the same – fluoride ions in the water.
2. Fluoridated water doesn’t work
Evidence for water fluoridation dates back to US studies in the 1940s, where dental researchers noticed lower levels of tooth decay in areas with naturally occurring fluoride in the water supply.
This prompted a study involving the artificial fluoridation of water supplies to a large community, and comparing the tooth decay rates to a neighbouring community with no fluoride.
The trial had to be discontinued after six years because the benefits to the children in the fluoridated community were so obvious it was deemed unethical to not provide the benefits to all the children, and so the control community water supply was also fluoridated.
Further reading: How fluoride in water helps prevent tooth decay
Since then, consistently we see lower levels of tooth decay associated with water fluoridation, and the most recent evidence, from Australia and overseas, supports this.
The NHMRC review found children and teenagers who had lived in areas with water fluoridation had 26-44% fewer teeth or surfaces affected by decay, and adults had 27% less tooth decay.
A number of factors are likely to influence the variation across populations and countries, including diet, access to dental care, and the amount of tap water people drink.
3. Fluoridated water causes cancer and other health problems
The NHMRC found, there was reliable evidence to suggest water fluoridation at current levels in Australia of 0.6-1.1 parts per million is not associated with: cancer, Down syndrome, cognitive problems, lowered intelligence, hip fracture, chronic kidney disease, kidney stones, hardening of the arteries, high blood pressure, low birth weight, premature death from any cause, musculoskeletal pain, osteoporosis, skeletal fluorosis (extra bone fluoride), thyroid problems or other self-reported complaints.
Further reading: Why do some controversies persist despite the evidence?
This confirms previous statements from the NHMRC on the safety of water fluoridation, and statements from international bodies such as the World Health Organisation, the World Dental Federation, the Australian Dental Association and the US Centers for Disease Control and Prevention.
Most studies that claim to show adverse health effects report on areas where there are high levels of fluoride occurring naturally in the water supply. This is often more than 2-10 parts per million or more, up to 10 times levels found in Australian water.
There is, however, evidence that fluoridated water is linked to both the amount and severity of dental fluorosis. This is caused by being exposed to excess fluoride (from any source) while the teeth are forming, affecting how the tooth enamel mineralises.
Most dental fluorosis in Australia is very mild or mild, and does not affect the either the function or appearance of the teeth. When you can see it, there are fine white flecks or lines on the teeth. Moderate dental fluorosis is very uncommon, and tends to include brown patches on the tooth surface. Severe dental fluorosis is rare in Australia.
4. Fluoridated water is not safe for infant formula
Some people are concerned about using fluoridated water to make up infant formula.
However, all infant formula sold in Australia has very low levels of fluoride, below the threshold amount of 17 micrograms of fluoride/100 kilojules (before reconstitution), which would require a warning label.
Therefore, making up infant formula with fluoridated tap water at levels found in Australian (0.6-1.1 parts per million) is safe, and does not pose a risk for dental fluorosis. Indeed, Australian research shows there is no association between infant formula use and dental fluorosis.
A consistent message
Adding fluoride to tap water to prevent tooth decay is one of our greatest public health achievements, with evidence gathered over more than 60 years showing it works and is safe. This latest review, tailored to Australia, adds to that evidence.
Population growth has profound impacts on Australian life, and sorting myths from facts can be difficult. This article is part of our series, Is Australia Full?, which aims to help inform a wide-ranging and often emotive debate.
Developed economies, including Australia, have increasingly been using international migration to compensate for demographic trend and skill shortages. Australia has one of the highest proportion of overseas-born people in the world: an estimated 26% of the total resident population was born overseas. This is expected to increase over the next decade.
So the health of immigrants and their use of health services are having increasing impacts on demands on the health system, its responsiveness, and the national health profile.
One of the most significant demographic trends in Australia today is the ageing of the population. This is an increase in the share of older people – defined as people aged 65 and older – relative to the youth (0 to 14 years) and working-age population (15 to 64 years). One in six Australians is now over 65, compared to one in seven in 2011 and only one in 25 in 1911.
The reasons for this trend are complex. These include the impact of the “baby boomer” generation and declines in fertility and mortality, combined with an increase in life expectancy.
Older people are living longer, which is an achievement of our health system. But an increase in life expectancy and decline in the death rate have created a paradoxical situation in which these older people have increased the country’s rates of illness and disability. This has led to a rise in health-care costs and an increase in use of health services, as well as hospitalisation.
While an ageing population adds to the burden on the health system, an intake of migrants who are generally young and healthier than the average Australian, due to their selectivity, might help balance this out. So, in fact, increasing migration would be of benefit to Australia’s health.
Australian immigrants are healthy
Australia uses something called the “points system” to determine the eligibility of most of those who apply to immigrate here. Points are given for productivity-related factors such as language, education, age (more points are given to younger applicants) and skills.
But it is reasonable to assume the points system would not apply to English migrants who arrived before the abandonment of the White Australian policy in 1973 and to New Zealand migrants. Together, these two groups make up a large proportion of the migrants from English-speaking countries. The points system also does not apply to those who migrate under the family, special eligibility, and humanitarian and refugee programs.
Having said that, skilled migrants selected under a points-based system make up most (around 68%) of all migrants in Australia. The rest (32%) taken in under the migration program come in through having a family member here.
Skilled migrants (and in many cases, their dependants) go through medical screening to meet minimum health requirements. The Department of Immigration and Border Protection specifies that, to meet the health requirement, an applicant must be free of a health condition that is:
- considered to be a threat to public health or a danger to the Australian community
- likely to result in significant health care and community service costs to the Australian community
- likely to require health care and community services that would limit the access of Australian citizens and permanent residents to those services as these are already in short supply.
Humanitarian migrants have a health waiver provision, but they make up a very small proportion of the total migration program.
Research has shown that immigrants tend to have better health status that the Australia-born populations. This health advantage narrows significantly over time, leading to their health becoming similar to that of Australians.
Migrants’ contribution to the workforce
Immigrants make up a substantial part of the health workforce in Australia. The international movement of health professionals is a major component of migration. Australia has been dependent on international medical graduates for a long time.
For example, according to an estimate by the Department of Health and Ageing, international medical graduates comprise about 39% of the medical workforce in Australia and 46% of general practitioners in rural and remote locations. Another estimate suggests 53% of medical practitioners in Australia are foreign-trained.
The dependence on international doctors will likely be maintained in future for a variety of reasons, such as to redress medical workforce maldistribution. Given Australia’s ageing patient and practitioner base and some key areas of the health workforce already in very short supply, this contribution of migrants is significant for Australia’s health profile.
Monitoring the health and well-being of immigrants is important for the overall health and public health systems in Australia. The issue of migrant health has become additionally important because the goal of Australia’s migration program has moved towards meeting the labour market needs of the economy. Good health is essential to fully realise the social and economic potential of immigrants.
We must also continue to collect and examine data on the health care needs and health service utilisation of Australian-born and foreign-born patients. Finally, we must educate ourselves about important contributions migrants make to ensure informed decisions are made to protect the public health system.
You can read other articles in the Is Australia Full? series here.
Recently, hospital and aged care provider Catholic Health Australia (CHA) released a report sounding an alarm bell at recent increases in the number of patients in public hospitals being urged to “go private”.
Public hospitals may encourage their patients to “go private” because it allows them to bill the patient’s health insurance and Medicare for costs incurred, rather than having to dip into their own limited budgets. Patients may be persuaded to use their private health insurance after being assured by the public hospital of no out-of-pocket costs, or being promised added extras such as a private room.
The report argued this trend may harm the private hospital sector by affecting profitability and investment decisions. It may also harm the interests of public patients if public hospitals discriminate in favour of treating private patients.
While aspects of these concerns may be valid, there may also be some benefits to public hospitals treating more private patients.
A look at the figures
The report is correct that the numbers of private patients in public hospitals are increasing, at an average of 10.5% per year since 2011-12. Public patients in public hospitals and private patients in private hospitals have also been increasing, but at slower rates of only 2.7% and 4.5% per year respectively since 2011-12.
But percentage rates of change can be misleading. In raw numbers, the increase in public patients in public hospitals (527,467) and private patients in private hospitals (576,135) has actually outstripped the raw increase in private patients in public hospitals (287,473). This is because public patient numbers are increasing from a much larger base (over five million) than private patients in public hospitals (less than one million).
Concerns with this trend
The CHA report notes several concerns with the trend of increasing private patients in public hospitals. They note anecdotal evidence of public patients being pressured to “go private” with incentives including drinks vouchers, better food options and free parking. While these reports may seem concerning, it’s hard to base any change of policy on anecdotal reports.
More worrying is the suggestion that publicly-admitted patients in public hospitals are being discriminated against, for example by being made to wait longer for treatment. The CHA report cites data from an Australian Institute of Health and Welfare report, which shows waiting times on public hospital waiting lists for public patients (at 42 days) was more than twice that of private patients in public hospitals (20 days).
But this difference is hard to interpret. There may be many differences in diagnosis and disease severity between public and private patients, which may explain the waiting time gap. So we can’t conclude this is evidence of any form of “discrimination” against patients without private health insurance in the public hospital system from these figures.
More robust evidence from public hospitals in NSW in 2004-05 does show private patients were prioritised over public patients. In this study, waiting times for elective surgery were found to be considerably shorter for private patients, despite having similar clinical needs as public patients.
Differences in waiting times between public and private patients were found to be largest for patients assigned to the lowest two urgency levels. In these cases, waiting times for public patients were more than twice as long as for private patients.
There is further evidence, also from NSW public hospitals, that public and private patients may be treated differently when they are assigned to an urgency category for waiting lists for elective surgery. The study suggested private patients were more likely to be assigned into more urgent admission categories, which corresponds with a shorter maximum wait for admission into hospital.
This study also found private patients were likely to receive more medical procedures while in hospital, but found no difference for length of hospital stay or, importantly, for mortality rates.
One claim of the CHA report is that there has been relatively “stagnant” growth of activity of private patients in private hospitals, potentially affecting their profitability and investment decisions.
First, the figures don’t seem to back this up. The increase in numbers of private patients in private hospitals is actually higher than the increase in numbers of private patients in public hospitals.
Second, even if private hospitals were losing business to public hospitals, it could be a welcome demonstration of competition in the health care market. The trend may be explained through public hospitals providing better amenities, higher quality, or lower costs than private hospitals.
There are some arguments to support continuing the practice of public hospitals admitting private patients. There can be efficiency gains to the health system given that the fees and charges for private patients in public hospitals are usually lower than those in private hospitals. So this form of competition could lower the costs in the health system as a whole.
Additional revenue raised by public hospitals could also support the continual provision of services and programs for public patients, which may have been curtailed due to budget cuts to the public hospital system.
The public hospital system is often seen as unfairly treated by the private sector in how it bears costs for training junior doctors (which takes place overwhelmingly in the public system), and treating the most severely ill patients. From this perspective, it seems only fair to allow public hospitals to take their “share” of the more profitable private patients.
Why we need better data
It’s important to figure out whether private patients are receiving preferential treatment at the expense of public patients. One study found abolishing preferential access for private patients and admitting patients according to when they were listed for an elective procedure would only lead to a small improvement in waiting times for public patients.
This is because long waiting times for public patients are primarily due to budget constraints in public hospitals, and not because private patients are skipping the queue.
The available robust evidence on the treatment of private patients in public hospitals is from more than a decade ago, and it’s unclear if the disparities between how public and private patients are treated have improved or worsened.
One reason for the lack of high quality research on this topic is the restriction on access to detailed hospital data in Australia, which we need for robust studies. If we had access to more detailed data, we could better understand what’s happening now, and ensure timely access to high quality hospital care for both public and private patients.
Last week I had a headache. Two hours in a traffic jam, hot day, no water, plans thrown into chaos. That day I was one of the five million Australians affected by headache or migraine. Over a year one person in two will experience a headache.
Headaches are really common, so here are five things the research evidence indicates are worth trying to help manage or avoid them.
A study was conducted in people who got at least two moderately intense or more than five mild headaches a month. The participants received a stress management and sleep quality intervention with or without increasing their water intake by an extra 1.5 litres a day.
The water intervention group got a significant improvement in migraine-specific quality of life scores over the three months, with 47% reporting their headaches were much improved, compared to 25% of the control group.
However, it did not reduce the number or duration of headaches. Drinking more water is worth a try. Take a water bottle everywhere you go and refill it regularly to remind you to drink more water.
Caffeine can have opposing effects. It can help relieve some headaches due to analgesic effects but also contribute to them, due to caffeine withdrawal. A review of caffeine withdrawal studies confirmed that getting a headache was the number one symptom of withdrawal, followed by fatigue, reduced energy and alertness, drowsiness, depressed mood, difficulty concentrating, fuzzy head and others.
When people were experimentally put though controlled caffeine withdrawal, 50% got a headache, with withdrawal symptoms occurring within 12-24 hours, peaking between 20-51 hours and lasting from two to nine days. Caffeine withdrawal can happen from a usual daily dose as low as 100 mg/day. One cup of brewed coffee contains 100-150mg caffeine, instant coffee has 50-100 mg depending on how strong you make it and a cup of tea can vary from 10-90mg. It appears that maintaining usual caffeine consumption may subconsciously relate to avoidance of withdrawal symptoms.
Caffeine can dampen down pain. in a systematic review that included five headache studies with 1,503 participants with migraine or tension-type headache, 33% of participants achieved pain relief of at least 50% of the maximum possible after receiving 100 mg or more caffeine plus analgesic pain medication (ibuprofen or paracetamol) compared to 25% for the analgesic group alone.
A study in over 50,000 Norwegians, who have high caffeine intakes (more than 400 milligrams a day), examined the relationship with headaches. Those with the highest caffeine intakes (more than 540mg/day) were 10% more likely to get headaches, including migraine.
But when headache frequency was examined, high caffeine consumers were more likely to experience non-migraine headaches infrequently (less than seven per month) compared to those considered low caffeine consumers (less than 240mg a day). This was attributed to potential “reverse causation” where high caffeine consumers use caffeine to damp down headache pain. They found those with the lowest caffeine intakes (125mg a day) were more likely to report more than 14 headaches per month, which may have been due to greater sensitivity and avoidance of caffeine.
Hypnic headaches are a rare type that occurs in association with sleep. They typically last 15-180 minutes and are more common in the elderly. Hypnic headaches are treated by giving caffeine in roughly the amount found in a cup of strong coffee.
Some people get a headache after fasting for about 16 hours, which equates to not eating between 6pm and 10am the next day. A study in Denmark found one person in 25 has been affected by a fasting headache. These headaches are most likely to occur when fasting for a blood test or medical procedure or if you are following a “fasting” weight loss diet or a very low energy meal replacement diet.
Fasting headaches are likely to be confounded by caffeine withdrawal. Check the test procedure instructions to see what fluids, such as tea, coffee and water are allowed and drink within those recommendations.
In a study 34 people with new-onset migraine who kept a headache diary for about a month, those who ate a night-time snack were 40% less likely to experience a headache compared to those who didn’t snack. For susceptible individuals this may prevent fasting headaches. Try a slice or wholegrain toast with a topping like cheese and tomato or avocado and tuna, with a cuppa.
Headache is the classic feature of alcohol induced hangovers. The amount of alcohol needed to trigger a hangover varies widely between individuals, from one drink to many. A number of factors mash up to produce a throbbing post alcohol headache. Increased urination and vomiting both increase risk of dehydration which leads to changes in blood and oxygen flowing to the brain.
Congeners, a group of chemicals produced in small amounts during fermentation, give alcoholic drinks their taste, smell and colour. Metabolites of alcohol breakdown in the liver can cross the blood-brain barrier contributing to hangover.
Alcohol can trigger tension-type headaches, cluster headaches and migraine. People with migraines have been shown to have lower alcohol intakes compared to others.
The wise advice is to drink responsibly, boost your water intake and don’t drink on an empty stomach. If you are sensitive to alcohol, avoidance is your best option.
5. Boost your intake of folate-rich foods
Some migraineurs are diet-sensitive. Triggers include cheese, chocolate, alcohol or other specific foods. A recent study found women with low dietary folate intakes had more frequent migraines. However a daily folic acid (1mg) supplement made no difference.
Boost your intake of foods rich in folate such as green leafy vegetables, legumes, seeds, chicken, eggs and citrus fruits. Use our Healthy Eating Quiz to check your nutrition, diet quality and variety. Keep a headache diary to identify triggers and then discuss it with your GP.
But our new study goes one step further. It predicts that higher taxes on sugar-sweetened drinks will benefit the wider economy through increased economic productivity, by having more, healthier people in paid and unpaid work.
Obesity delivers a double whammy
A total of 63% Australian adults and one in four children are overweight or obese, making this both a health and an economic problem.
Obesity increases the risk of diseases including cancer, diabetes, heart disease and stroke. Obesity has also been estimated to cost Australia about A$8.6 billion a year or more. Not only does obesity drive up health-care costs, by causing illness and premature death, it also reduces people’s ability to work and contribute to the economy.
Added sugar contributes energy to the diet, but no useful nutrients. Increasingly, health experts suggest we should be treating sugar, and in particular sugar in soft drinks, as we do tobacco or alcohol, by taxing it to reduce consumption and so reduce obesity rates.
Taxing sugar is not a new concept. In the 1700s, Scottish economist Adam Smith wrote in An Inquiry into the Nature and Causes of the Wealth of Nations:
Sugar, rum, and tobacco, are commodities which are nowhere necessaries of life, which are become objects of almost universal consumption, and which are therefore extremely proper subjects of taxation.
Smith’s proposal to tax sugar was not aimed at improving health, as it is today. Now organisations like the World Health Organisation, the Australian Medical Association and many non-governmental organisations are advocating a tax on drinks with added sugar, as part of wider efforts to tackle obesity.
What we did and what we found
Until our study, few worldwide had looked at the wider economic effects of taxing sugary drinks.
We modelled the Australian adult population as it was in 2010, in terms of consumption of sugar-sweetened drinks, body mass, obesity-related diseases, death rates, and the amount of paid or unpaid work people were likely to do.
We compared a scenario in which the prices of sugared drinks went up by 20%, compared to business-as-usual, and estimated what difference this would make for the number of obese people, the number of years lived, and for overall economic production.
Further reading: Dietary guidelines don’t work. Here’s how to fix them
We used data from the 2011-12 Australian Health Survey and found that obese people aged 15-64 had a lower chance of being in a paid job, compared to people whose weight was normal. We assumed this was related to illness.
Of people in work, obese workers needed more sick leave, but only about an hour a year.
We also looked at unpaid work (like cooking, cleaning and caring, and volunteer work). We included gains due to more people surviving for longer due to lower body weight. We assumed that if work was not done as unpaid work, somebody would have to be hired to do it (so there would be a replacement cost).
Our results show that a 20% sugar tax would mean about 400,000 fewer people would be obese. Three-quarters of these would be in the workforce, so that about 300,000 fewer employed people would be obese.
Over the lifetime of the adult population of Australia in 2010, this would add about A$750 million to the formal, paid economy, due to more, healthier people producing more goods and services.
The gains in unpaid work were even larger at A$1.17 billion. Fewer obese people means more healthy people, who have a greater likelihood to do unpaid work, in the household or as volunteers.
These indirect economic benefits from increased employment in the workforce and from greater participation in unpaid work were larger than the savings in health care costs, which we estimated at about A$425 million over the lifetime of the adult population.
In all, the tax could deliver over A$2 billion in economic benefits in indirect economic benefits plus health care savings. And that does not even include the value of the gains in people’s quality of life and how long they lived.
Further reading: Fat nation: the rise and fall of obesity on the political agenda
The exact size of the benefits depend on assumptions about what people would drink (and eat) if they drink fewer sugared drinks. In this study, we used Australian evidence that found an increase only for diet drinks, which contain virtually no energy.
Other evidence finds a sugar tax reduces the consumption of sugar and energy-rich foods, but may also lead to people eating fewer fruit and vegetables and more salt. This would reduce the health benefit, and that study suggests it would be even better to tax all sugar instead of only sugared drinks.
Nevertheless, the available evidence shows health benefits of increased taxation of sugared drinks.
What’s happening overseas?
Studies in other countries have predicted similar effects of a sugar tax on the proportion of obese people. For example, a 20% tax is expected to reduce the number of obese people by about 1.3% in the UK and 2-4% in South Africa.
And an increasing number of countries, including the UK, France, Denmark, Finland, Hungary and recently Estonia and Saudi Arabia, have already announced or have implemented a tax on drinks with added sugar.
If Australia introduces a 20% tax on sugar-sweetened drinks, as many health advocates and economists have called for, that would not only improve health, our results predict it would also promote economic growth.
The author of this article will be available for a live Q&A today 1-2pm. Please post your questions in the comments below.
As we get older we have a greater risk of developing impairments in areas of cognitive function – such as memory, reasoning and verbal ability. We also have a greater risk of dementia, which is what we call cognitive decline that interferes with daily life. The trajectory of this cognitive decline can vary considerably from one person to the next.
Despite these varying trajectories, one thing is for sure: even cognitively normal people experience pathological changes in their brain, including degeneration and atrophy, as they age. By the time a person reaches the age of 70 to 80, these changes closely resemble those seen in the brains of people with Alzheimer’s Disease.
Even so, many people are able to function normally in the presence of significant brain damage and pathology. So why do some experience symptoms of Alzheimer’s and dementia, while others remain sharp of mind?
It comes down to something called cognitive reserve. This is a concept used to explain a person’s capacity to maintain normal cognitive function in the presence of brain pathology. To put it simply, some people have better cognitive reserve than others.
Evidence shows the extent of someone’s cognitive decline doesn’t occur in line with the amount of biological damage in their brain as it ages. Rather, certain life experiences determine someone’s cognitive reserve and, therefore, their ability to avoid dementia or memory loss.
How do we know?
Being educated, having higher levels of social interaction or working in cognitively demanding occupations (managerial or professional roles, for instance) increases resilience to cognitive decline and dementia. Many studies have shown this. These studies followed people over a number of years and looked for signs of them developing cognitive decline or dementia in that period.
Cognitive reserve is traditionally measured and quantified based on self reports of life experience such as education level, occupational complexity and social engagement. While these measures provide an indication of reserve, they’re only of limited use if we want to identify those at risk of cognitive decline. Genetic influences obviously play a part in our brain development and will influence resilience.
The fundamental brain mechanisms that underpin cognitive reserve are still unclear.
The brain consists of complex, richly interconnected networks that are responsible for our cognitive ability. These networks have the capacity to change and adapt to task demands or brain damage. And this capacity is essential not only for normal brain function, but also for maintaining cognitive performance in later life.
This adaptation is governed by brain plasticity. This is the brain’s ability to continuously modulate its structure and function throughout life in response to different experiences. So, plasticity and flexibility in brain networks likely contribute in a major way to cognitive reserve and these processes are influenced by both genetic profiles and life experiences.
A major focus of our research is examining how brain connectivity and plasticity relate to reserve and cognitive function. We hope this will help identify a measure of reserve that reliably identifies individuals at risk of cognitive decline.
Strengthening your brain
While there is little we can do about our genetic profile, adapting our lifestyles to include certain types of behaviours offers a significant opportunity to improve our cognitive reserve.
Activities that engage your brain, such as learning a new language and completing crosswords, as well as having high levels of social interaction, increase reserve and can reduce your risk of developing dementia.
Regular physical activity also improves cognitive function and reduces the risk of dementia. Unfortunately, little evidence is available to suggest what type of physical activity, as well as intensity and amount, is required to best increase reserve and protect against cognitive impairment.
There is also mounting evidence that being sedentary for long periods of the day is bad for health. This might even undo any benefits gained from periods of physical activity. So, it is important to understand how the composition of physical activity across the day impacts brain health and reserve, and this is an aim of our work.
Our ongoing studies should contribute to the development of evidence-based guidelines that provide clear advice on physical activity patterns for optimising brain health and resilience.