Medical Hypotheses (2005) 65, 380–388
http://intl.elsevierhealth.com/journals/mehy
The complementarity model of brain–body relationship Harald Walach
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Samueli Institute for Information Biology, European Office, Institute of Environmental Medicine and Hospital Epidemiology, Freiburg University Hospital, Hugstetter str. 55, 79106 Freiburg, Germany Received 6 December 2004; accepted 6 January 2005
Summary We introduce the complementarity concept to understand mind–body relations and the question why the biopsychosocial model has in fact been praised, but not integrated into medicine. By complementarity, we mean that two incompatible descriptions have to be used to describe something in full. The complementarity model states that the physical and the mental side of the human organism are two complementary notions. This contradicts the prevailing materialist notion that mental and psychological processes are emergent properties of an organism. The complementarity model also has consequences for a further understanding of biological processes. Complementarity is a defining property of quantum systems proper. Such systems exhibit correlated properties that result in coordinated behavior without signal transfer or interaction. This is termed EPR-correlation or entanglement. Weak quantum theory, a generalized version of quantum mechanics proper, predicts entanglement also for macroscopic systems, provided a local and a global observable are complementary. Thus, complementarity could be the key to understanding holistically correlated behavior on different levels of systemic complexity. c 2005 Elsevier Ltd. All rights reserved.
Introduction The biopsychosocial model [1] is still a popular theoretical basis for medical care. Looking into medical research and practice one gets the impression that it is not well understood, except, perhaps, in specialized disciplines such as psychosomatics and psychoneuroimmunology, since medical care is still
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Tel.: +49 761 270 5497; fax: +49 761 270 7224. E-mail addresses: walach@ukl.uni-freiburg.de, walach@uniklinik-freiburg.de.
harald.
compartmentalized, and the bridge between care for the physical and mental side of patients’ suffering is not commonly implemented [2]. In this paper, we wish to offer a basis for better understanding this notion, which is modeled around the concept of complementarity [3], and show how important this notion could be for future progress, both in theoretical and practical aspects of medicine. The notion of ‘‘complementarity’’ will be used in a looser sense than it has been defined for quantum physics [4], but in a stricter sense than it is normally used in the colloquialism of complementary and alternative medical approaches (CAM) or
0306-9877/$ - see front matter c 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.mehy.2005.01.029
The complementarity model of brain–body relationship everyday language. Before doing this, let us recall the basic idea introduced by Engel [1].
The biopsychosocial model and its ramifications This model was the first influential attempt to introduce systems theoretical ideas as originally proposed by Bertalanffy [5,6] and applied to the living by others [7–9] into medicine. The general idea was that linear-causal thinking as entailed by Newtonian physics is not quite adequate to understand biological, let alone medical phenomena. Different causes can have the same outcome, many causes can contribute to a final common pathway, but none of the single causal elements would be enough to create the final state by itself. In the same sense, different therapeutic interventions can be used to combat a diseased state, although starting at different systemic levels of living organization. This is so, because systems theory understands living beings as organisms that are composed of simpler elements, which in themselves have autonomous organizations, which are part of holistic structures that form larger wholes. Thus, a human organism is composed of interconnected organs, which are composed of many specialized cell-systems, which in turn are made of well-organized systems of cell organelles. These are formed, regulated and structured by proteins, macromolecules, amino-acids and genes, which ultimately are composed of atomic structures. The important point here is to keep in mind that on each level of organization a newly formed structure acquires a certain kind of boundary, even though it might only be transitory, and this system thereby attains some form of autonomy which makes it a kind of semi-independent player in a set of partially autonomous systems and well organized interrelations. For instance, an atom acquires stability by virtue of the specific composition of nuclear particles and depending on the number of such particles, different atoms have different qualities or emergent properties. The same is true on the cellular level: different cells, by virtue of their organization, acquire autonomy and thereby new qualities emerge. Different integrations of cells into organs produce different qualities of the organs, and so on. The key concept here is that of ‘‘emergent property’’. Emergent properties are properties that themselves are not part of, predictable by, or derivable from the components or elements of a certain system. Emergent properties arise as a function of the structure and the interrelations of those elements forming a system [10]. Exactly when and how an emergent property arises is not
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at all understood well at the moment, but entanglement (see below) plays a key role in it [11]. For instance, once a system has acquired a certain amount of complexity, it can replicate itself. This is called autopoiesis [9]. While rocks, consisting of comparatively simple crystal-lattice structures, cannot replicate or create the environment for their replication themselves, bacteria can. Thus, complexity gives rise to properties not found in its component parts, called ‘‘emergent properties’’. Other examples of emergent properties in living systems are the faculty of long range electrical and chemical communication in nerve cells, the detection of non-self molecules in immuno-competent cells, the complex cognitive operations of certain cognitive systems in the brain, or the well balanced launch of an up and downregulation of an immune response in order to combat an intruding microorganism without in general harming the organism itself. The emergence of new properties within complex systems has been described as non-linearity in biological systems, which dissipate energy and thereby build up complexity, order and new structures [12–14]. This inherent non-linearity in biological systems is the reason for the often observed clinical fact that a certain amount of a potentially noxious stimulus can be harmless, or even strengthening, while only a small increase in quantity might tip the balance and turn a protective effect into a harmful one. Examples of such effects include hormesis effects [15], where small amounts of toxic substances can be protective of higher doses [16], or the empirical observations showing that a certain amount of alcohol intake might be protective, for instance of dementia [17], or coronary artery disease [18,19], while higher doses are harmful. If our organism were a linear system, toxic substances would always be toxic and never protective, and an increase in dosage would result in an increase in toxicity, and never in a change of a protective or wanted effect into a toxic or unwanted effect. We do not normally see this non-linearity, because we only look at small windows of dose-response relationships, where the behavior of the system is quasi-linear. This non-linearity is also the reason for the law of initial value [20] stating that in activated organisms the same stimulus might have the opposite effect compared with inactivated organisms, a fact which explains that a certain dose of a substance like alcohol can have stimulating effects in initially calm subjects but the same amount in agitated subjects might lead to a calm state. This situation – non-linearity, partial independence of systems with complex interactions and emergent properties of more complex systems –
382 is also the reason for the fact that the same state of affairs – a disease or a cure – can be understood and brought about by quite different, sometimes opposite processes. For instance, an infection is normally viewed as an invasion of a host by foreign pathogens. The normal treatment would be antibiotic or antiviral, combating the cause, and this treatment is generally effective. However, the sole reliance on this line of reasoning in medicine and its extrapolation to food production and the massive preventive treatment of cattle has produced the problem of resistance in bacteria, which necessitates the development of new antibiotics. Because of the adaptive evolutionary mechanisms of bacteria this race cannot be won by relying solely on this strategy. A systems-theoretical or biopsychosocial view would shift the emphasis towards the host and its susceptibility, or towards the system at large, which comprises overuse of disinfectants in hygiene, misuse of antibiotics in cattle rearing, and disuse of inappropriate antibiotics treatment in practice, as well as an understanding of improved host resistance. It is known, for instance, that psychological factors such as stress [21–23], compromise the immune system, because the immune system is, among others, also susceptible to conditioning [24]. Therefore, psychological interventions, like hypnosis, can be used to enhance resistance to infection [25]. For these reasons, it is at least conceivable that a holistic intervention, like homeopathy, which is currently not at all understood, could have an effect in infectious diseases. It has been observed that homeopathy is effective in childhood diarrhea [26–28], and especially in such cases where a microbiological origin of the disease has been documented [27,28].
Amending the systems perspective by complementarity The biopsychosocial model explains how higher levels of systems organization have to be taken into account and that such a model gives a rational basis to a psychosomatic approach. It has been made plausible that, in principle, taking into account of higher systemic levels – family, social networks, society at large – leads to a better understanding of a disease and potentially to a more comprehensive and effective treatment. Yet when looking into both the practice and research of medicine, this approach has not really been integrated into either. We propose here that the reason for this is the sole reliance of medicine on the material composition of systems and the neglect of consciousness as a complementary side of human
Walach beings. This tacitly promotes a materialist concept of medicine and biology, and the implicit pre-supposition [29] that consciousness can be understood as an emergent property much in the same sense as reproduction, self-control, autonomy have been introduced as emergent properties in the above paragraphs. We contend that this identification of consciousness with an emergent property of material systems is a category mistake and a fatal flaw in theoretical concepts which entails much of the critique by the public of the medical system and the popular desire for alternative approaches in CAM [30]. We propose in what follows an alternative theoretical basis which tries to remedy the implicit supposition that consciousness is an emergent property of the material composition of the human organism, yet keeps the general systems perspective which has been found valuable. Our approach will hinge on the concept of complementarity as introduced by Bohr to denote two incompatible descriptions of one and the same object, which exclude each other and are at the same time necessary for a full description of it [31,32]. We will elaborate on this notion below. We propose to view consciousness not as an emergent property, but as a complementary aspect to material systems organization, in the sense of a neutral monist position. This, at first sight, only seems to be a slight shift of emphasis compared to the emergentist notion. But it has massive implications, as we will hope to show.
Complementarity and the consciousness problem Many attempts have been made to understand the consciousness and its relationship to the body. The view favored by most scientists seems to be the one just outlined that consciousness can be understood as an emergent property of a complex system [33,34], or is even superfluous as a theoretical entity [35,36], or to put it bluntly, some materialist solution of the mind–body problem. Although it has been, in our view, convincingly shown that any materialist account encounters stark problems [37], dualist positions are intuitively difficult, because they violate the principle of parsimony and create problems of their own, like the one how two categorically different substances should communicate, and the like. Therefore, some thinkers have preferred what is normally termed a neutral-monist position, where both body and consciousness or matter and mind are seen as two aspects of a single general princi-
The complementarity model of brain–body relationship ple, which at some level of complexity appears in two seemingly mutually exclusive ways. Originally introduced by Spinoza [38], a variant was developed by Leibniz [39], and favored by Jung [40]. In modern times, the most influential writer subscribing to such a view was probably Feigl [41]. It has been pointed out that the notion of ‘‘complementarity’’ analogous to the one developed by quantum physics might be a good theoretical concept to describe this view [42]. When borrowing the notion of ‘‘complementarity’’ from physics, it is important to understand its original meaning [32,43], as well as the history of the term [44]. Historically, Niels Bohr had taken the term from the psychology of his days, where it had first been used by William James to describe the simultaneous presence of different personalities in clinical cases, or by Alfred Rubin to describe the simultaneous presence of two different pictorial images in one picture in his famous puzzling pictures, such as the well known ‘‘chalice-faces’’ picture. Bohr transferred this connotation into physics without naming his sources. In the usage introduced by him and later on codified in quantum mechanics, complementarity denotes aspects of a quantum system which cannot be measured simultaneously with arbitrary precision. More precisely, complementary descriptions of a system are maximally incompatible (and not only contradictory or opposites), and yet necessary to describe one and the same system. Practically, one has to make a decision which of a pair of complementary observables (i.e. measurable qualities of a system) to measure first, for instance momentum. This will make it impossible to measure its complementary counterpart, position at the same time, and vice versa. Complementarity is, therefore, tightly linked with the uncertainty relation characteristic of quantum measurements of complementary observables like position and momentum [4]. The algebraic version of quantum mechanics has taken into account complementarity by an algebra of non-commuting operators [45]. Thereby, it is meant that complementary observables are mapped by non-commuting operations, for which the sequence of measurements is decisive. Thus, outcomes are different for different sequences of measurements of non-commuting or complementary observables. For instance, if the position of a particle is measured first, and its momentum second, the result will be different than if momentum is measured first, and position second. The measurements of such complementary observables and the mathematical descriptors or
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operators representing them are called ‘‘noncommuting’’, because their sequence does make a difference. While our normal, Abelian, algebra, is commutative – 2 \ 3 is the same as 3 \ 2 – the algebra used to formally describe complementary relationships in quantum mechanics is non-commutative – i.e. a \ b is not the same as b \ a. Thus, operational and formal non-commutativity as formulated in the algebraic formulation of quantum mechanics is the conceptual expression of complementarity. While in quantum mechanics proper complementarity is well defined as non-commutativity of operations, it is not at all well understood outside the formal language of physics. Nevertheless, such an interpretation of complementarity in terms of non-commuting operations can also be useful for therapeutic disciplines, albeit in a less stringent way. For instance, it makes a difference whether we first understand and diagnose a patient and then treat him, or first treat and then diagnose him. In that sense, treatment and diagnosis are complementary notions in that they are both necessary for understanding a concept, in this case medical care, but they cannot be applied at the same time and mutually exclude and at the same time imply each other. They can only be applied in a sequence and the sequence of application makes a difference. A metaphor for this would be that in an ideal world complementary notions determine a concept in a higher order dimensional framework, but for our cognitive limitations we have to use them sequentially and thus they appear as excluding and at the same time implying each other. Germane to the notion of complementarity is thus that complementary concepts are mutually exclusive and yet necessary to describe a concept completely. They are not exclusive in the same sense as opposites or contradictory statements exclude each other, but complementary concepts are maximally incompatible. Thus, the opposite of ‘‘diagnosis’’ is not ‘‘treatment’’ but ‘‘no diagnosis,’’ and the opposite of treating a patient is not treating him. But the complementary concept to diagnosis is treatment. They are maximally incompatible in the sense that they normally cannot be applied at the same time with the same precision. The fact that in medicine we know of cases were the diagnosis is the treatment [46], as in re-assuring patients that nothing is really wrong with them, or that treatment is also diagnosis, as in some cases of psychotherapy, testifies to the fact that the notion of complementarity outside physics loses some of its theoretical rigor. Still, we wish to use the term in this sense and not just in the colloquial one of something complementing a given situation, as
384 when somebody says ‘‘complementary medicine’’ meaning an approach which is used additionally to conventional care. Applying the concept of complementarity to consciousness and the mind–body problem has the following consequences: in a complementary view, mental phenomena and physical phenomena both co-determine human nature. Both are primary in the sense that neither can be reduced to the other notion. They seem to be mutually exclusive concepts and yet they imply each other. They are mutually exclusive in an explanatory sense, because mental and physical phenomena cannot be simply reduced to each other and denote different kinds of being. When looking at pain, for instance, we have the physical side of it, which is well understood. Noxious stimuli lead to an activation of alpha fibers, release of substance P that enhances the activity of neurons in certain brain areas which we associate or correlate with pain experience. But the material correlate, the firing of pain-associated neurons in the brain, is not identical to the pain experience itself, to the feeling of ‘‘what it is to be in pain’’. And the experience of ‘‘being in pain’’ is completely different in category from the firing of nerve fibers. There is as yet no bridge across this Cartesian cut, and in that sense both descriptions exclude each other, because they cannot be converted into each other [37]. Yet both are necessary to describe the situation in full. Leaving one side out of the picture is a misrepresentation. Both aspects cannot normally be known at the same time, with the same precision, but only sequentially. For instance, when studying pain, we can choose to look at the neurological substrates, and hook subjects to physiological equipment like MRI-scanning machines, analyze cerebrospinal fluid for substance P, monitor local serotonin and histamine. This will give us a more or less clear picture of the physiological side. But then we cannot, at the same time and with the same precision, know about the experience of pain, since we have to alter the situation to make our measurements and thereby alter the experience. On the other hand, if we want to know about the experiential side of pain and interview a patient, we will take care not to disturb the relationship by invasive measurements. As the mental and the physical aspects are noncommuting the sequence may be of importance. For instance, while it can be life-saving in cardiac arrest to first attend to the physical side and initiate resuscitation, and only attend to the psychological and family side of the myocardial infarction at later stages, the reverse can be true for a survivor of psychic trauma such as torture,
Walach childhood sexual abuse or attempted murder. By not understanding the psychological side of it properly and by medicalizing such a patient, a labeling process might be initiated which could prove difficult to reverse. On the other hand, if the complementary side is not taken into account complete healing or treatment might be difficult, too. Thus, in a cardiac arrest patient a successful rehabilitation program will address psychological, behavioral and family issues at some stage, while in a trauma survivor it might be necessary at times to introduce the help of psychopharmacological interventions to combat symptoms of sleeplessness, anxiety or depression. It has been argued that mind and body can be seen as a result of an initial break of symmetry in the quantum physical sense of the word [47]. Whenever in physics a symmetry is broken, two or more qualitatively new elements arise. For instance, in the standard model of cosmic expansion of the big bang, the original symmetry break resulted in the unfolding of the known forces out of one superforce and gave rise to the diversification of matter which we today know as our universe [48]. In Atmanspacher’s model [47], quantum mechanics is taken at its ontic level. This is a complete description of all possibilities in the world, without a temporal ordering, in an everpresent now. When this temporal symmetry is being broken, the distinction between mind and matter arises from a general, basic underlying symmetry or ontic reality which is normally described by the ontic level of quantum mechanics as exemplified in the Schro ¨dinger equation. However, both, mind and matter, remain correlated, with matter following a forward time and efficient causation, and mind following a backward time description and final causation. Thus, in this model mind and matter are complementary aspects of one underlying reality. The consequences of such a more formal approach are worth considering.
Consequences Holistic approaches Some of the practical consequences have already been hinted at above. It can readily be seen that a complementarist stance as opposed to a materialist–emergentist one has immediate consequences for care and therapeutic approaches. It would entail that the complementary aspect of a chosen approach has always to be taken into
The complementarity model of brain–body relationship account. While this may sometimes only have a theoretical meaning and asymptotical practical consequences, as in suturing a lesion due to an incidental car accident, where the mental side of the human being is normally only marginally involved, it can have dramatic consequences as in the examples provided in the above paragraph. Not taking into account the mental-psychological side of myocardial infarction is tantamount to dismissing a lot of high quality evidence of the behavioral and affective causes of arterial stenosis, from lifestyle, diet and illness behavior like smoking to the affective sides like bereavement or depression [49]. Likewise, limiting one’s interventions only to the physical side by lowering fat lipids, treating angina symptoms, laying bypasses, and providing healthier diets is equal to respecting only the physical element of the complementary mind–body pair. If illness behavior like smoking, unrewarding work situations [50], or other untoward psychological and social elements are not addressed and thus the complementary mental elements are left out, a medical therapy is running the risk of not producing maximum benefit. Thus, an obvious consequence of a complementary approach to the mind–body problem in medicine is the taking into account of the complementary side of a given therapy, diagnosis or situation, knowing that although one side might be in the forefront, the other side has to be acknowledged, too, if the picture is to be complete and the therapy thorough. This should be compulsory for the treatment of chronic problems. For it is in those that a purely and exclusively physical-medical approach has the most drawbacks in terms of long-term side-effects of pharmacological treatments, recurrences, or risk of dependence on drugs or the medical system at large, all of which incur tremendous costs for the community. It is the one-sided subscription to an implicit materialist–ermergentist worldview, we hold, which makes the medical community prone to overlooking the manifold and sometimes strong evidence from psychosomatics, behavioral medicine or public health and which explains the lack of integration of these findings into therapeutic approaches.
Generalized entanglement But there is also a more covert and intriguing consequence of an approach based on the complementarity of mind and body. We have shown that complementarity can possibly also be used beyond quantum mechanics proper as a meaningful theoretical concept and that under certain circum-
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stances this could lead to entangled states in macro-systems and outside the realm of quantum mechanics proper [45]. Entanglement is known from quantum mechanics as a correlational correspondence of parts of a quantum system which is not mediated by signals. This follows from the formalism of quantum mechanics, and has been shown to be a well-documented empirical fact [51,52]. In entanglement a quantum system behaves as if its parts ‘‘knew’’ of each others’ behavior. Thus, when one element of a quantum system is measured, its counterpart instantaneously exhibits a corresponding value, predicted by the equations of quantum mechanics, without a signal mediating this correspondence. That this is a fact for the quantum world and thereby that nature is non-local, because distance in space and time does not change or affect these EPR-like correlations, is a well-accepted fact among physicists. But it is unclear whether these entangled states could also have any relevance for the everyday macroscopic world medicine is part of. Our analysis and presentation of a weak version of quantum theory (weak quantum theory – WQT) which is applicable to different types of systems [45] suggests that this is the case. In fact the understanding of mind and matter as asymptotically disjoint representations of one underlying reality [47] suggests that the relationship between mind and matter could be the result of such entangled states in one system. Weak Quantum Theory predicts as a consequence of its formalism that whenever a local and global observable pertaining to a system are complementary, entanglement or EPR-like correlations within that system ensue. More precisely, when the global observable or description of the whole system and local observables or descriptions of certain elements within that system are complementary, entanglement between these elements ensues. This situation is graphically represented in Fig. 1. Let us assume that the description of the elements of the system, symbolized by the squares are complementary to the description of the whole system, symbolized by the oval boundary of the system, while other elements (small circles or triangles) do not have a description complementary to the global one. Following the formalism of WQT, we would expect entanglement between all the elements symbolized by the squares. In other words, we would expect a correlated behavior between those elements, without any signals or interactions mediating this correlated behavior. Thus, there could be coordinated, correlated behavior within a system, which is not mediated by causal signals, such as enzymes, transmitters,
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Figure 1 Graphic representation of generalized entanglement: elements of a system whose description is complementary (arrows) to the description of the whole system are entangled (connecting lines).
or receptors, but which is due to entanglement, which again is the result of the complementarity between components of the system. The formal conditions for generalized entanglement to occur within the body, or indeed also between physical and mental systems, could be, for instance, conceptualized as the complementarity between connectedness and separation, or being segregated and an individual entity, and at the same time being part of a communal structure. Let us denote this joint structure as ‘‘individuality’’ and ‘‘community’’ or ‘‘individuality in community’’. They are not reducible to each other: a separate individual cannot be reduced to the community he or she is part of and vice versa. An organ is a separate and separable entity from the rest of the organism and cannot be reduced to it, and at the same time cannot be isolated from it without destroying both. Individuality and community, we hold, are complementary descriptions. Thus, wherever we have communal structures, like the organism, uniting individually discernible entities, we would expect entanglement between those entities. We would expect correlated behavior between cell structures belonging to one cell, and between cells belonging to one organ, and between organs belonging to one organism, and between organisms belonging to one community, like a family. These correlated behaviors would not have to be mediated by any classical signal, according to our model. Such a view could have profound theoretical and practical consequences. It could help to understand long-range coupling within cellular systems or organs, which are as yet difficult to understand in terms of local–causal interactions. It could help to understand the high correlation between placebo and drug treatment in trials, which we [53,54] and others [55,56] have observed. Such a
Walach model could help to understand the complex interactions, the genome has with its environment and thus explain adaptive mutation [57]. Such a correlational ‘‘mechanism’’ could complement existing channels of information transfer, such as the genetic code, causal pathways of molecular or electromagnetic interaction, and does of course neither exclude them nor diminish their importance. Above all, however, such a model could help understand how a correspondence between the mental and the physical, between psychological and bodily states, could be understood and form an eventual scientific understanding for the correspondence between mind and body, which Leibniz once compared to two entrained clocks. It goes without saying that this last consequence of complementarity is at the moment still speculative, although formally and theoretically sound. It hinges completely on the question of whether and how the notion of complementarity can be meaningfully applied outside the realm of physics and unequivocally adapted to a theoretical or practical medical context. We hope to have pointed out that this is at least feasible. It remains to be seen, whether the consequences of the formalism of WQT can be analyzed within meaningful examples of medical science and can be used to make firm predictions, which can be experimentally tested. With quantum entanglement proper, it was finally a precise operationalization and rigorous experimental testing that brought the idea that was known all along since Schro ¨dinger’s time into the foreground of scientific research. In the same sense it remains to be seen, whether generalized entanglement is a feature of our reality or just an idea. Some empirical data [58–60] point to the possibility that this idea might have some merit, but the final word will be spoken through direct experimental testing.
Acknowledgments H.W. is sponsored by the Samueli Institute of Information Biology, Corona del Mar, CA. The ideas expressed in this paper have grown over the years and have been greatly helped and clarified in many discussions with Hartmann Ro ¨mer, Freiburg.
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