Theory of homeostasis

Risk homeostasis theory: an overview

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OPINION • DISSENT

Risk homeostasis theory: an overview

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Gerald J S Wilde

Department of Psychology, Queen's University, Kingston, Ontario K7L 3N6, Canada

Correspondence to: Professor Wilde.

http://dx.doi.org/10.1136/ip.4.2.89

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risk homeostasis theory

There is an odd coexistence between two conflicting safety policies that may well be pursued by the same accident prevention agency. The first seeks to improve safety by alleviating the consequences of risky behaviour. It may take the form of seat belt installation and wearing, airbags, crashworthy vehicle design, or forgiving roads (collapsible lamp posts and barriers). This policy offers forgiveness for a moment of inattention or carelessness. The second policy seeks to improve safety by making the consequences of imprudent behaviour more severe and includes things such as speed bumps, narrow street passages, and fines for violations. Here, people are threatened into adopting a safe behaviour; a moment of inattention or carelessness may have a dire outcome.

While these two policies seem logically contradictory, neither is likely to reduce the injury rate, because people adapt their behaviour to changes in environmental conditions. Both theory and data indicate that safety and lifestyle dependent health is unlikely to improve unless the amount of risk people are willing to take is reduced.

Choice of denominator

In any discussion about injury prevention the criterion of success should be clearly specified, or else confusion abounds.^1,² What is it that we want to achieve: fewer accidents per unit distance driven? Per hour of exposure to traffic? Or per head of population per year?

Sometimes the choice of denominator is obvious. We wish to reduce the number of suicides per head of population, not per pistol or km of available rope. Success in promoting electrical safety is not measured in terms of fewer cases of electrocution per kwh consumed.

In the domain of traffic, do we want to provide more mobility per case of death or injury, or do we want fewer cases of death and injury? That these two measures of success are not interchangeable is clearly demonstrated by data from the US. Between 1927 and 1987, the death rate per km driven fell by a factor of about 9, but the death rate per 100 000 inhabitants showed no clear secular trend, neither upward nor downward. Similarly, during a period of steady economic growth, between 1955 and 1972, Ontario saw a major reduction in the traffic death rate per unit distance driven, but an increase per capita.³ From a public health point of view, the injury rate per head of population is the most relevant, and that is why that denominator will be used here.

Effect of the business cycle on injuries

Traffic injury rates show major fluctuations from one time period to another, and it has been established that these fluctuations go hand in hand with the business cycle: in years of high unemployment and low industrial production the per capita death rate is low.⁴

It may be argued that the increased traffic death rate in periods of relative economic prosperity is due to an increased inclination of people to expose themselves to risk on the road. In these periods, more money is to be made by more and faster mobility while the costs of gasoline and car repairs relative to dispensable income are reduced. In depressed economies the death rate on the road is reduced because both amount and riskiness of driving fall for the opposite reasons.

Accepted level of injury risk

Besides macroeconomic influences, there are other factors that influence the level of accepted risk; these are of a cultural, social, or psychological kind. In general, the amount of risk that people are willing (in fact, prefer) to take can be said to depend on four utility factors and will be greater to the extent that factors 1 and 4 are higher, and factors 2 and 3 are lower:

The expected benefits of risky behaviour alternatives (examples: gaining time by speeding, fighting boredom, increasing mobility).
The expected costs of risky behaviour alternatives (examples: speeding tickets, car repairs, insurance surcharges).
The expected benefits of safe behaviour alternatives (examples: insurance discounts for accident-free periods, enhancement of reputation of responsibility).
The expected costs of safe behaviour alternatives (examples: using an uncomfortable seat belt, being called a coward by one's peers, time loss).

The level of risk at which the net benefit is expected to maximize is called the target level of risk in recognition of the realization that people do not try to minimize risk (which would be zero at zero mobility), but instead attempt to optimize it.³ Risk homeostasis theory posits that people at any moment of time compare the amount of risk they perceive with their target level of risk and will adjust their behaviour in an attempt to eliminate any discrepancies between the two. Each action carries a certain level of injury likelihood such that the sum total of all actions taken by people over one year explains the accident rate for that year. This rate, in turn, has an effect on the level of risk that people perceive and thus upon their subsequent decisions, and so forth.

This homeostatic mechanism is depicted in fig 1 and constitutes a case of circular causality: a change in the degree of caution displayed in behaviour brings about a change in the injury rate, while a change the injury rate also leads to a change in behaviour. The phenomenon is similar to a thermostat: this instrument controls the actions of the heating/cooling unit which controls the temperature and this in turn controls the actions of the thermostat. There will be fluctuations in the room temperature, but averaged over time, the temperature will remain stable, unless the thermostat is set to a new target (set point) level.

Figure 1

Homeostatic mechanism.

Similarly, the target level of risk is seen as the controlling variable in the causation dynamic of the injury rate. It follows that the basic strategy of injury prevention should be to reduce the level of risk that people are willing to accept.

Because of the closed loop nature of the control process, all other variables, such as variations in skill or environmental conditions can only produce minor and/or short term fluctuations, and these are often reduced or virtually eliminated through anticipatory adaptation (“feed forward control”). ⁵

Evidence of risk homeostasis

In the fall of 1967 Sweden changed over from left hand to right hand traffic. This was followed by a marked reduction in the traffic fatality rate. About a year and a half later, the accident rate returned to the trend before the changeover. In terms of fig 1, what happened was a sudden surge in box b as a result of the changeover coming into effect. Perceived risk (box b) was suddenly significantly higher than the target level of risk (box a). Road users adjusted their behaviour by choosing much more prudent behaviour alternatives (box d). As a result, the fatal injury rate dropped (box e). After some time (f), however, people discovered—through the mass media as well as their own experiences—that the roads were not as dangerous as they had thought they were. The level of perceived risk dropped and less often exceeded the target level of risk. Consequently, road users opted for less cautious behaviour alternatives and the fatal injury rate rose again. ³

Numerous other findings can be explained by risk homeostasis theory. In road sections where the accident rate per km driven is low, drivers move faster. Mandatory wearing of seat belts reduces the likelihood of death or injury in case an accident happens, but does not reduce the death rate per capita.³ Similarly, “... airbag equipped cars tend to be driven more aggressively and that aggressiveness appears to offset the effect of the airbag for the driver and increases the risk of death to others”.⁶ Cars outfitted with antilock brakes are driven faster, more carelessly, and closer to the car in front, braked more abruptly, and have no lower accident rate per hour of exposure than cars without these devices.^3,^7,⁸ Similarly, with better road lighting motorists drive faster and pay less attention.⁹

Driver training or a mandatory course of driving on slippery roads does not reduce accident risk.^3,¹⁰ Such training does indeed improve skill, but it apparently increases confidence even more, with the end effect that driver education graduates show a higher accident rate per capita.

The introduction of childproof medicine vials has failed to limit the number of cases of accidental poisoning. These, in fact, became more frequent, apparently as the result of parents becoming less careful in the handling and storing of the “safer” bottles.¹⁰ A recent Swedish study showed that the more traffic safety education children in kindergarten and primary school had received, the higher their traffic injury rate. This was attributed to the greater independence and mobility, including the use of a bicycle, that better trained children were allowed.¹²

Incentives for safety

On the other hand, incentive systems for accident-free operation have been shown to be a very powerful method for the reduction of injury rates. Incentives, that is, future rewards contingent upon fulfilling a future condition, increase the perceived benefits of safe behaviour alternatives (utility factor 3 above). There have been many studies of the effectiveness of incentive schemes, both in industrial settings and traffic and their most productive features have been identified. Injury rate reductions ranging from 10 to 90% have been observed. The only undesirable side effect noted so far is the underreporting of accidents, but this phenomenon is limited to relatively minor injuries and property damage. Among their positive side effects is a more congenial social climate.³

The remarkable effectiveness of incentive programmes is arguably due to the fact that they enhance people's perceived value of the future. The prospect of future gratification causes people to look forward to the future with positive expectation. They will thus have a greater desire to be alive and well when that future comes (utility factor 3 above), and be more inclined to take action to protect their health and safety. And indeed, there is evidence accumulating that individuals who are marked by a high valuation of the future relative to the present display fewer unsafe behaviours and unhealthy lifestyles.¹³ In a recent Canadian study of late adolescents and early adults, a significant relation was found between safe driving practices, regular seat belt use, and moderate alcohol consumption on the one hand and a high valuation of the future on the other. ¹⁴

Conclusion

The theory of risk homeostasis (also known as “risk compensation”) was primarily developed and validated in the area of road safety. Some of the supporting data, however, come from quite different behaviour domains including smoking and settling in flood prone territories. This is not surprising because the mechanisms that are involved in risk homeostasis are probably universal. Moreover, the accident prevention strategy that follows from risk homeostasis theory has been found effective in many areas. Incentives for safety and health may be viewed as one example of a wider class of (not technological but) “expectationist” interventions which offer people more positive anticipations regarding their future than is currently the case and thus motivate them to be more cautious with life and limb.

References

↵
Wilde GJS. On the choice of denominator for the calculation of accident rates. In: Yagar S, ed. Transport risk assessment. Waterloo, Ontario: University of Waterloo Press, 1994:139–54.
↵
Wilde GJS. Risk homeostasis theory and traffic accidents: propositions, deductions and discussion of dissension in recent reactions. Ergonomics 1988;31:441–68.
↵
Wilde GJS. Target risk: dealing with the danger of death, disease and damage in everyday decisions. Toronto: PDE Publications, 1994.
↵
Wilde GJS, Simonet SL. Economic fluctuations and the traffic accident rate in Switzerland: a longitudinal perspective. Berne: Swiss Council for Accident Prevention, 1996.
↵
Wilde GJS. The theory of risk homeostasis: implications for safety and health. Risk Analysis 1982;2:209–25.
↵
Peterson S, Hoffer G, Millner E. Are drivers of air-bag-equipped cars more aggressive? A test of the offsetting behavior hypothesis. Journal of Law and Economics 1995;38:251–64.
↵
Fosser S, Sageber F, Sætermo AF. Behavioural adaptation to antilock brakes—drivers keep a shorter distance. Nordic Road and Transport Research 1996;8:21–2.
↵
Grant BA, Smiley A. Driver response to antilock brakes: a demonstration of behavioural adaptation. Proceedings of the Canadian Multidisicplinary Road Safety Conference VIII. University of Saskatoon, Saskatchewan, Canada, 14–16 June 1993.
↵
Björnskau T, Fosser S. Road lighting increases safety—but motorists drive slightly faster and pay less attention. Nordic Road and Transport Research 1996;8:20.
↵
Christensen P, Glad A. Mandatory course of driving on slippery roads does not reduce the accident risk. Nordic Road and Transport Research 1996;8:22–3.
Viscusi WK. The lullling effect: the impact of child-resistant packaging on aspirin and analgesic ingestions. American Economic Review 1984;74:324–7.
↵
Johansson BS. Trafiktränade barn löper större olycksrisk. Väg-och Transportforskningsinstitutet Aktuellt 1997;4(June):9.
↵
Björgvinsson T, Wilde GJS. Risky health and safety habits related to perceived value of the future. Safety Science 1996;22:27–33.
↵
Björgvinsson T. Health and safety habits as a function of the perceived value of the future. [Doctoral dissertation.] Kingston, Ontario: Department of Psychology, Queen's University, 1998.

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An Evolutionary View of Homeostasis: Bioenergetics, Life History Theory, and Responses to Pregnancy | Integrating Evolutionary Biology into Medical Education: for maternal and child healthcare students, clinicians, and scientists

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Perlman, Robert, 'An Evolutionary View of Homeostasis: Bioenergetics, Life History Theory, and Responses to Pregnancy', in Jay Schulkin, and Michael Power (eds), Integrating Evolutionary Biology into Medical Education: for maternal and child healthcare students, clinicians, and scientists (

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, 2019; online edn, Oxford Academic, 20 Feb. 2020), https://doi.org/10.1093/oso/9780198814153.003.0007, accessed 7 Apr. 2023.

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Abstract

Physiologists and evolutionary biologists have traditionally investigated different but complementary aspects of biological phenomena. Homeostasis, the maintenance of approximately constant conditions in bodily fluids, has been the purview of physiology. Evolutionary insights can, however, deepen our knowledge of homeostatic regulatory mechanisms. Bioenergetics has been of central concern to both physiology and evolution. Physiologists have been interested in the energetic content of foods, in the metabolic transformations of the energy derived from foods, and in the energetic costs of physiological processes, while evolutionary life history theory addresses the ways that organisms have evolved to acquire and allocate metabolic energy throughout their life course. Engineering control theory highlights the limitations as well as the benefits of different regulatory mechanisms and so helps to explain why we have evolved multiple integrated and cooperative homeostatic mechanisms. The physiological responses to pregnancy illustrate the ways in which an evolutionary perspective enriches our understanding of homeostasis.

Keywords: bioenergetics, control theory, evolutionary medicine, homeostasis, life history

Subject

Genetics and GenomicsDevelopmental BiologyEvolutionary Biology

Collection: Oxford Scholarship Online

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a different look at the causes of mental health disorders — RISE on vc.ru

What if depression is, first of all, not a disease, but a natural reaction of the brain to life events?

1361 views

Hello! This is Dmitry Raiz, the author of the R153 project, in which I talk about the effective use of the brain and ways to increase its performance with the help of nootropics and mental practices.

It is often the special substances and therapies that help to cope with anxiety, fatigue or depression. Usually we perceive these conditions as problems that need to be dealt with. But there is another point of view, according to which all this is just a reaction of the body and an attempt by the brain to adapt to a possible future.

The best physicians of ancient Greece believed that the functions of the body and brain depended on the balance of the four "humor fluids". Too much or too little of just one of these, according to the teachings of the time, caused pain, dysfunction, or behavioral and emotional instability.

This theory dominated until the 19th century, when medical professionals realized that "humorism" was mostly rubbish. But they still believed that health depended on some kind of bodily balance.

The next big theory - "the prevailing explanation of the principle of physiological regulation" from the end of the 19th century to the present day - was "homeostasis".

In short, according to the theory of homeostasis, the human body has a basic state that it seeks to maintain. Its goal is constancy, and diseases and disorders are the consequences of deviations from the "points of homeostasis" or unsuccessful attempts of the body to return to them. So homeostasis shows that a healthy body and a healthy mind are codependent.

Type 1 diabetes is often cited as an example of how homeostasis works. Lack of insulin causes dangerous spikes in blood glucose levels, and insulin injections help restore the balance.

But some experts question the idea that the body tends to maintain some predetermined position.

Homeostasis is about maintaining the same state, while most of the physiological systems are constantly changing and adapting to changes.

Jay Shalkin, Neuroscientist at the University of Washington

Shalkin's work is devoted to a new concept of human health and functioning of the body - "allostasis", or "stability in change." According to the theory of allostasis, the body and brain are designed to constantly expect changes and adapt to them based on experience, and not to maintain balance.

For example, levels of digestive enzymes and energy-transport hormones rise before meals. At the same time, the scale of the increase depends on what a person eats and when. If he habitually eats unhealthy and sweet foods, an increase in enzymes and hormones - including those that contribute to poor metabolism and the development of type 2 diabetes - will occur, even if a person switches to more healthy meals in the process.

Allostasis considers "diseases and disorders" of homeostasis as a logical response to external events and stimuli - even if it has some negative effects. “Allostasis takes into account the environment, the social context and our adaptation to them,” Shalkin says.

According to him, homeostasis has dominated medicine and its approaches to research and treatment for too long. By changing the scientific community's understanding of how the brain and body work, allostasis could make medical education more useful, especially when it comes to mental states like anxiety and depression. “We need a theory like allostasis that takes into account how we adapt to change in our lives or fail to do so,” Shalkin says.

Allostasis and mental health

Anxiety disorders, depression and other mental problems are often described as the result of a chemical imbalance in the brain. This "homeostasis" approach has flourished for decades and is the basis of modern pharmacology. Correcting imbalances—for example, increasing serotonin levels—improves mood and focus.

But allostasis supporters have a different opinion on this matter. Although mental problems are associated with elevated or decreased levels of neurotransmitters, there is no conclusive evidence that it is this instability that causes them. "Drugs blindly modify systems that we simply don't understand," says Peter Sterling, professor of neuroscience at the University of Pennsylvania and author of What is Health? Allostasis and the Evolution of Human Design.

According to him, although this modification often helps to relieve symptoms, it does nothing about the original causes of the problems. Altering neurochemical levels can harm other aspects of mood and consciousness, and in some cases even paranoia, anger, and other negative effects.

Sterling and his late colleague Joseph Ayer coined the term "allostasis" and developed and refined this model for 30 years. According to Sterling, the main difference between allostasis and homeostasis is the understanding that the brain and body are constantly trying to anticipate and adapt by changing human consciousness and behavior. “For the brain, the most efficient way to control the body is to know ahead of time what it needs,” says Starling.

The concept of allostasis explains why a person whose life is filled with stress can become very anxious and experience phenomena such as high blood pressure, heart palpitations and indigestion even when he is not in danger. Instead of returning to the original state that homeostasis offers, the brain adapts based on experience.

In her paper, Starling explains how an "allostasis" understanding of the brain and body can help maintain mental health. Proper mindfulness meditation, cognitive behavioral therapy, and other non-drug programs designed to lead to constructive thoughts, desires, and conscious behavior use the brain's adaptation mechanisms for therapeutic purposes.

According to Sterling, by changing life experiences, people can remodel their own "circuits" to alleviate mental difficulties.

Concept shake

Not everyone likes the idea of allostasis. Some experts say that this is just a reorganization and "rebranding" of the concepts of homeostasis. Others consider these disputes only semantic entertainment, which has little to do with health and medicine. But many agree that new models of health perception are needed. Especially mental.

Peter Kinderman, Professor of Clinical Psychology at the University of Liverpool, believes that modern language for discussing mental problems demonizes logical and predictable responses to life situations. It may be better to treat some difficulties as an experience rather than a violation.

For example, during the pandemic, more people showed signs of depression and anxiety. The response to a threat to loved ones and society is not a "dysfunction in the biology of the brain." So describing these problems in more appropriate language would help people move on, rather than just struggle with problems.

This conceptual debate is not likely to end any time soon, and this is only part of the debate about how modern life is breaking all records in the number of mental illnesses and existential problems.

"Homeostasis doesn't explain why half of the world's population is diabetic or obese, or the high number of 'deaths of despair,'" says Starling. are simply incomprehensible to us." According to him, the development of an "allostasis" model of the functioning of the body can help us with the listed problems, the cases of which are becoming more and more.

Thank you for reading to the end! Tell us in the comments what you think about the theory of allostasis. Maybe you have your own opinion about what causes mental illness?

And if you want to learn more about how the brain works and how to improve its functioning with the help of nootropic substances and not only, subscribe to my Telegram channel and VKontakte group.

There are short posts about various complexes, substances and practices, as well as announcements of such large articles.

How mathematics can help us understand the human body

Scientists claim that graph theory helps biologists to study homeostasis, writes eurekalert. org.

Healthy human bodies are good at regulating: our temperature remains at 98.6 degrees Fahrenheit, no matter how high or low the temperature around us. Blood sugar levels remain fairly constant, even when we drink a glass of juice. We keep what we need the amount of calcium in the bones and in other parts of our body.

We couldn't survive without this regulation called homeostasis. And when systems fail, illness and sometimes death.

In presentations at the annual meeting of the American Association promote science researchers have argued that mathematics can help explain and predict these failures, potentially offering new ways to prevent and treat in situations where something goes wrong.

Homeostasis "is a biological phenomenon, and without it biological systems don't work, said Marty Golubitsky, one of the speakers and an eminent professor of natural and Mathematical Sciences at Ohio State University. - And, if you had detailed, accurate mathematical models, you could numerically explore these systems, find places where this control really happens, and where there is a failure, and understand how it to correct".

Scientists are well versed in the biological reasons why this regulation happens: certain systems in our bodies must remain constant in order to function and support our bodies. However, the underlying mathematics this is less reliable.

But understanding homeostasis, including predicting it changes and calculation of ways to keep the body in regulation, despite failures in the body systems that manage these regulators, may be a way to provide targeted medical helping people who need it, said Janet Best professor of mathematics at Ohio State.

"It's part of precision medicine," said Best, who also is co-director of the Institute of Mathematical Biological Ohio State Sciences. “People are different and you need a model that can work with different people. And we think that's what we're here for developed."

Researchers at MBI and other institutions studying the relationship mathematicians and biology, have built models that explain how the body maintains homeostasis in various systems. At the core of these models lies the graph - a mathematical concept that tries to explain how objects are related to each other. (If you studied algebra or geometry in high school, you probably learned some basics of graph theory.)

Golubitsky and Best said graph theory could help explain and predict changes in homeostasis in the body. According to them words, this explanation may be useful to biologists and others professionals looking for ways to intervene in case of violation homeostasis. This decay causes a number of problems - for example, it can expressed as an excess of glucose in the human blood or insufficient amount of calcium in his bones.

The AAAS presentations focused both on graphics, which models how the body regulates dopamine levels through homeostasis, and how graph theory helps define charting properties that can help predict homeostasis.

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