Tuesday 1 May 2018

Psychiatry’s inchoate wish for a paradigm shift and the bio-psych-social model of mental illness

Overview

In recent years, there have been repeated calls for a ‘paradigm shift’ in psychiatry. In this chapter, I take this idea seriously and explore its consequences. Having illustrated calls for a paradigm shift, I sketch the Kuhnian account of science from which the idea is taken and highlight the connection to incommensurability. I then outline a distinction drawn from Winch between putative sciences where the self-understanding of subjects plays no role and those where it is fundamental and I argue that psychiatry falls into the latter kind. This suggests that the wish for a paradigm shift in psychiatry is either incoherent or a wish for a radical but unforeseeable overhaul of a significant aspect of our self-understanding as subjects and agents. The bio-psych-social model of mental illness is thus a helpful reminder of the cost of a paradigm shift in psychiatry.

Introduction: the inchoate desire for a psychiatric paradigm shift

During preliminary discussions of the development of DSM-5 (then referred to as ‘DSM-V’), there was a widespread assumption expressed that psychiatry needed a ‘paradigm shift’. For example, in the introduction to A Research Agenda for DSM-V the [Kupfer et al 2002], the editors, including the DSM-5 Task Force Chair Dr. David Kupfer claimed that:

limitations in the current diagnostic paradigm suggest that research exclusively focused on refining the DSM-defined syndromes may never be successful in uncovering their underlying etiologies. For that to happen, an as yet unknown paradigm shift may need to occur. Therefore, another important goal of this volume is to transcend the limitations of the current DSM paradigm. [Kupfer et al 2002: ix bold added]

In a paper published 8 years later (but before DSM-5) called ‘Paradigm Shifts and the Development of the Diagnostic and Statistical Manual of Mental Disorders: Past Experiences and Future Aspirations’, one of those editors, Michael First, expressed pessimism about such a possible radical change.

Work is currently under way on the preparation of DSM-5, which is due in May 2013. From the outset of the DSM-5 revision process in 1999, its developers were hopeful that the changes would be so significant so as to constitute a paradigm shift in psychiatric diagnosis. [First 2010: 691 bold added]

Despite hopes that DSM-5 may be able to move beyond its current descriptive categorical paradigm as a result of the fruits of the past 16 years of scientific research, based on A Research Agenda for DSM-V, the DSM-5 research planning conference presentations, and the initial drafts of the DSM-5 proposals, it seems evident that DSM-5 will continue to follow the DSM-IV paradigm, namely, a descriptive categorical system augmented by dimensions. Any future paradigm shift will have to await significant advances in our understanding of the etiology and pathophysiology of mental disorders. [ibid: 698 bold added]

Allan Frances, the Task Force Chair of the previous DSM-IV later described the initial optimism about the possibility of such a change as ‘absurdly premature’.

The DSM-V goal to effect a “paradigm shift” in psychiatric diagnosis is absurdly premature. Simply stated, descriptive psychiatric diagnosis does not now need and cannot support a paradigm shift. There can be no dramatic improvements in psychiatric diagnosis until we make a fundamental leap in our understanding of what causes mental disorders. The incredible recent advances in neuroscience, molecular biology, and brain imaging that have taught us so much about normal brain functioning are still not relevant to the clinical practicalities of everyday psychiatric diagnosis. The clearest evidence supporting this disappointing fact is that not even 1 biological test is ready for inclusion in the criteria sets for DSM-V. [Frances 2009a: 2 bold added]

Elsewhere, in ‘Whither DSM-V?’ he wrote:

Not surprisingly, the disappointing conclusion of all this effort was that there are no biological markers even remotely ready for inclusion in DSM–V. The good news is that the remarkable revolutions in neuroscience, molecular biology, and genetics of the past three decades have given us great insights into the functioning of the normal brain. The bad news is that our understanding of psychopathology is fairly primitive and may remain so for some time… Thus, it is obvious that our field lacks the fundamental understanding of pathogenesis that will be required before we can take the next meaningful step forward towards a paradigm-shifting aetiological model of diagnosis. [Frances 2009b: 391 bold added]

Such passages imply that the nature of the radical shift envisaged was a turn towards a biological disease model for psychiatry and that this was undermined by the lack of biological markers for psychiatric diagnostic categories. But even those who rejected a disease model still appealed for a ‘paradigm shift’. In a position paper written in the same year as DSM-5 was published, the British Psychological Society wrote:

The DCP [Division of Clinical Psychology] is of the view that it is timely and appropriate to affirm publicly that the current classification system as outlined in DSM and ICD, in respect of the functional psychiatric diagnoses, has significant conceptual and empirical limitations. Consequently, there is a need for a paradigm shift in relation to the experiences that these diagnoses refer to, towards a conceptual system which is no longer based on a ‘disease’ model. [British Psychological Society 2013: 1 bold added]

Since the publication of DSM-5, hope for a biological disease model for psychiatry has been placed, instead, on the NIMH’s Research Domain Criteria (RDoC). It is not a rival taxonomy but rather a research framework to underpin new approaches to investigating mental disorders.

RDoC itself does not propose an alternative nosology, but rather seeks to unfetter research from clinical definitions and provide an initial framework and set of constructs for reconceptualizing psychiatric research directions in line with basic neuroscience concepts… The RDoC framework seeks to reorient conceptions of psychopathology by encouraging infusion of neuroscientific thinking and data into such conceptions. [Hettema 2016: 349]

NIMH gave emphasis to RDoC as a paradigm with the hypothesis that research based on already defined behavioral constructs with known neural circuits will accelerate the development of fundamental knowledge applicable to psychopathology while reducing problems associated with heterogeneous clinical syndromes. [Carpenter 2016: 562 bold added]

In ‘Research domain criteria: a final paradigm for psychiatry?’, the philosopher of psychiatry Walter Glannon sums up an assessment with the claim that:

Despite its limitations, RDoC offers the most conceptually coherent and scientifically sound paradigm for explaining psychiatric disorders. [Glannon 2015: 3]

As I will explain (briefly) below, the fact that RDoC is not a rival taxonomy to DSM-5 but a framework and set of constructs for research provides some rationale for the use of the label ‘paradigm’. But aside from that specific feature of RDoC, the mere fact of the broader assumption that psychiatry is generally thought to need a paradigm-shift is worthy of note. It suggests the question: for what does one hope if one hopes for such a thing? ‘Paradigm’ is the great term of art of the historian of science Thomas Kuhn, author of The Structure of Scientific Revolutions [Kuhn [1962] 1996]. In the next section, I will draw out some of the consequences of this on a broadly Kuhnian picture of science. Central to this picture is the connection between paradigms and the meaning of theoretical terms and hence the connection between changing paradigms and the consequent incommensurability of the meanings of terms across time. It is this that helps to support Kuhn’s theoretical scepticism about whether sciences can be said to progress. And this in turn calls into question whether it can be rational to wish for a paradigm shift.

In the third section, I address a related but more substantial point. Whilst the wish for a paradigm shift typically reflects optimism about the developments of neuroscience, psychiatry aims to use its technical innovations to relieve human distress. An improved psychiatry should thus be better able to address those issues. But if so its understanding of mental illness and distress - which guides diagnosis, treatment, management and shared plans for recovery - had better remain closely wedded to the self-understanding of those it is supposed to help. And if so, any plans for a paradigm shift threatens either to disconnect medical psychiatry from the understanding of human agents which should guide it or to revise in unforeseeable ways much of every day human self-understanding. But in order to prepare the way to that conclusion, I will briefly outline the role of paradigms and paradigm shifts in Kuhn’s account of science.

Paradigms, paradigm shifts and incommensurability

The widespread and sometimes indiscriminate use of the word ‘paradigm’ in the description of scientific change is the result of the popularity of Thomas Kuhn’s Structure of Scientific Revolutions in which it is a key term [Kuhn 1996]. Margaret Masterman (a pupil of Wittgenstein and founder of the Cambridge Language Research Laboratory) identified 21 different ways in which Kuhn used the word but suggested that there were three main ideas [Masterman 1970: 61]. These are paradigm as metaphysical world-view, a sociologically describable body of activity and a particular concrete instance such as a textbook. To shed light on these it will be helpful to offer a thumbnail sketch of his account of scientific practice.

Kuhn argues that scientific activity falls into two sorts. In the main, scientists are engaged in ‘normal science’. This comprises the articulation and application of stable dominant theories and meta-theoretical assumptions to new areas. Kuhn refers to both background worldview and the agreed forms of activities with the word ‘paradigm’ (the first and second of Masterman’s uses). The paradigm offers a way of seeing the world and one such tool is a paradigmatic worked example, or classic solution (Masterman’s third sense). The business of normal science is puzzle solving: using familiar methods to arrive at solutions to problems against a background assumption that the paradigm provides the resources for such solutions.

As I advertised above, these characteristics suggest a rationale for calling RDoc a ‘paradigm’ as it is broader than just a taxonomy to rival DSM-5 but rather encourages a particular approach to explaining mental illness emphasising biological and neurological causes. It offers a way of seeing mental illness as a biological disease.

During periods of normal science, no serious attempt is made to refute or even defend the theoretical background and shared practices, which are instead simply presupposed. But these stable periods of normal science are punctuated by brief periods of revolutionary theory change. Sparked both by the accumulation of anomalous results – such as ‘puzzles’ that resist solution – and by the development of rival theories or even rival meta-theoretical assumptions, the dominant orthodoxy is cast aside and a new theory or set of theories put in its place. Only during these revolutionary periods is the truth of what will become the new scientific background called into question.

Thus, while during periods of normal science, some measure of progress can be based on an increasing ability to solve recognised puzzles against the background of a stable paradigm, that measure does not apply over periods of revolutionary change.

In the first place, the proponents of competing paradigms will often disagree about the list of problems that any candidate for paradigm must resolve. Their standards or their definitions of science are not the same. [Kuhn 1996: 148]

This reason for a lack of a common measure – the claim that standards of assessment are internal, and hence relative, to a paradigm is called ‘the incommensurability of standards’. But it is not the only reason to think that different paradigms are incommensurable.

More is involved, however, than the incommensurability of standards. Since new paradigms are born from old ones, they ordinarily incorporate much of the vocabulary and apparatus, both conceptual and manipulative, that the traditional paradigm had previously employed. But they seldom employ these borrowed elements in quite the traditional way. Within the new paradigm, old terms, concepts, and experiments fall into new relationships one with the other. The inevitable result is what we must call, though the term is not quite right, a misunderstanding between the two competing schools. [ibid: 149]

This source of incommensurability follows from his, at the time, influential view of the meaning of theoretical terms. Like other philosophers and historians of science, Kuhn reacted against an influential view of the meaning of theoretical terms taken from the Logical Empiricists of the 1930s [Feigl 1970]. On that older view, theories could be judged against the standard of theoretically neutral observations and that separation was supposedly maintained by the independence of observation from theoretical language. Although theoretical terms were grounded in the observational predictions they collectively inferentially warranted, observational terms were thought to be definable antecedently.

A group of arguments towards the end of the twentieth century undermined that distinction between theory and observation (establishing instead the ‘theory dependence of observation’) [eg. Churchland 1979, Hanson 1958, Kuhn 1996]. Kuhn concludes that the holism that had been thought to apply to theoretical terms – albeit a holism constrained from the outside by their implications for observation claims – must apply to theoretical and observational terms collectively. But without a stable set of neutral observation claims against which to judge them, the new holism seems to imply that a change of overall theory would change the context and hence the meaning of all now hybrid theory-observation terms. This seems to suggest that there is no standard by which to compare overall theories across a paradigm change since different paradigms defined different scientific languages leaving no resources for an objective translation manual. Translation depends instead on difficult judgements about the best way to render one description into another. And thus, paradigm change is incommensurable undermining the very idea that science progresses.

Kuhn himself notoriously suggests that, after such a shift, scientists inhabit a different world.

These examples point to the third and most fundamental aspect of the incommensurability of competing paradigms. In a sense that I am unable to explicate further, the proponents of competing paradigms practice their trades in different worlds. [Kuhn 1996: 150]

This is not the only way to view the meaning of theoretical terms and thus not the only view of the impact on the possibility of comparing theories of potential meaning change. One possible alternative, motivated by referential approaches to meaning influenced by Putnam, puts weight on the role of actual samples in fixing the extension of scientific terms [Putnam 1975]. But part of the force of the idea of a paradigm shift is that the change of worldview is radical and Kuhn’s view of meaning incommensurability is part of the reason for that. Any less radical account of the consequences of theory change would undermine the point of deploying the suggestive phrase ‘paradigm shift’.

This, however, suggests that, at the very least, there is something strange about psychiatry’s frequently expressed wish to usher in a new paradigm. Without a standard by which to judge progress across such a change, what rational motive is there to wish in advance for such a change? By what pre-shift standard can a replacement be said to be rationally preferable? Afterwards, there might equally be no grounds for rational regret and perhaps even a parochial preference for the newly familiar, but that does not provide a rational argument to favour the change.

That, however, is not my main purpose in recalling the close connection between paradigms, meaning and incommensurability. The main issue concerns the application of these ideas to psychiatry in particular. In the next section I will suggest that a paradigm shift would come at a high price for psychiatry and that the apparent willingness to pay that price suggests a radical scepticism about solving psychiatry’s current conceptual problems.

Scientific and lay understanding of mental illness

In order to develop my main concern, I will return to (and re-quote) the passage from Frances I quoted at the start. The most obvious reason for thinking that psychiatry is awaiting a paradigm shift are developments at the hard science end of psychiatry. Even Frances mentions ‘incredible recent advances in neuroscience, molecular biology, and brain imaging’ when discussing others’ confidence in the possibility of a new paradigm. Frances himself argues that ‘descriptive psychiatric diagnosis does not now need and cannot support a paradigm shift’ but he goes on to say that there ‘can be no dramatic improvements in psychiatric diagnosis until we make a fundamental leap in our understanding of what causes mental disorders’ and that the absence of biological tests in diagnostic criteria suggests that this has not been reached. But that comment does not distance himself from what might seem a plausible aspiration for a bio-medical psychiatry. What is needed, on this assumption, is greater biological understanding of ‘what causes mental disorders’ and a sufficiently ‘fundamental leap’ in that might give us the hoped-for paradigm shift.

I think there are two fundamental complexities that this view – a view from which Frances does not sufficiently distance himself – ignores. The first is that, within psychiatry, the focus of neuroscientific, biological and brain imaging technology is, nevertheless, mental pathology. Progress has been recently made in these areas and more progress is needed but, additionally, progress is also needed in determining not just what causes mental disorders but what they comprise. What is it, in other words, for something to be a mental disorder? There is no reason to think that an answer to this question can be provided by neuroscience, molecular biology, and brain imaging since, insofar as these can help shed light on psychopathology, one needs first to have decided the extension of that concept then to study its neurological and biological underpinnings. Given the conceptual complexity of the very idea of mental disorder, and that what is so classed is so contested, any leap forward in knowledge of brain mechanisms needs to go hand in hand with answers to that question.

The second complexity follows from the first. Suppose that innovations in neuroscience, molecular biology, and brain imaging were used to articulate a form of psychopathology on the basis of its neurological similarity to currently identified forms but which had no connection to any mental distress or suffering. That would not, I suggest, mark a triumph of neuroscientific psychiatry. Rather, it would amount to psychiatry losing its way by losing its connection to its particular distinct subject matter.

This point suggests a more general moral that derives from the Wittgensteinian philosopher Peter Winch’s arguments in The Idea of a Social Science and its Relation to Philosophy [Winch 1958]. Winch argues that there can be no such thing as a social science. The argument for this conclusion starts from the assumption that a central element of understanding meaningful behaviour is an understanding of the nature of rules. For this he draws on Wittgenstein’s lengthy discussion of rules, rule following and understanding in the Philosophical Investigations [Wittgenstein 1953]. Winch makes three claims:

1. Rules are central to so-called social science because actions are constituted as the actions that they are by the rules that govern them. Thus, to give one of his examples, putting a cross on a piece of paper is an act of voting given the right context of rules. Sound patterns, similarly, are constituted as meaningful assertions only given the rules of spoken language.

2. Explaining an action by citing a rule presupposes a grasp of the rule not just by the putative social scientist but also (to a first approximation) by the agent whose behaviour is being explained.

3. Rule following is grounded in implicit practical knowledge of what actions count as going on in the same way. Rule following cannot rest entirely on explicit linguistically codified knowledge because that explicit knowledge would require further implicit knowledge of how the written prescription is to be understood.

Rules also have a further implicit but important feature. They are normative: they prescribe correct and incorrect moves. In the example mentioned above, they prescribe the difference between a successful vote and a spoiled ballet paper. Only certain actions count as casting a vote. Thus, if understanding an event involves relating it to a rule, this form of understanding involves a notion of correctness. It involves understanding what makes it correct or appropriate as a piece of voting behaviour. This is not the same as saying that most votes are cast at a particular time of day or night or by a particular socio-economic proportion of the electorate. That may be discovered by empirical study. But the normative rules that characterize an event as an act of voting are not provided by any such statistical generalizations. With these claims in place, Winch goes on to argue that so-called social science is fundamentally dissimilar to natural science.

[W]hereas in the case of the natural scientist we have to deal with only one set of rules, namely those governing the scientist’s investigation itself, here what the sociologist is studying, as well as his study of it, is a human activity and is therefore carried on according to rules. And it is these rules, rather than those which govern the sociologist’s investigation, which specify what is to count as ‘doing the same kind of thing’ in relation to that kind of activity. [Winch 1990: 87]

In understanding social phenomena, the understanding possessed by the objects of study (human subjects, people) of their own behaviour plays a key role and this is not reflected in say the physics of billiard ball motion. The putative social scientist has to understand social behaviour by understanding it, at least in part, through the understanding that the agents he or she studies have. That is not to say that the analysis of social phenomena can go no further than agents’ self-understanding. But it is rooted in it.

I do not wish to maintain that we must stop at the unreflective kind of understanding of which I gave as an instance the engineer’s understanding of the activities of his colleagues. But I do want to say that any more reflective understanding must necessarily presuppose, if it is to count as genuine understanding at all, the participant’s unreflective understanding. [Winch 1990: 89]

Winch himself uses these points to argue, contentiously, that there can thus be no such thing as social science and, even more contentiously, that the proper study of social phenomena is continuous with philosophical analysis. Neither of these conclusions is necessary, however, for the more modest point that there is an important distinction between cases where the understanding of phenomena by those who are – or what is –being studied is important and those where it plays no role.

Psychiatry, unlike a more disinterested study of the brain, has an essential connection to human distress and suffering and to norms governing social dysfunction, emotional dysregulation etc. Thus, it has an essential connection to the concepts with which we, as subjects and agents, make sense of ourselves. The implication from Winch’s analysis is that norms, deviation from which constitute mental illnesses, have to be understood, at least initially, via agents’ self-understanding of them. This suggests a distinction between psychiatry and some at least of the natural sciences. While there seems to be no constraint imposed by the subject matter of much of natural science on the limits of conceptual innovation (as long as the concepts arrived at can still be understood by at least some scientists), the concepts of psychiatry need to retain some connection to those concepts in terms of which we ordinarily make sense of ourselves. Only so, can human experiences play at least some guiding role for psychiatric diagnosis, theorising and care.

Implications for psychiatric paradigm shifts and bio-psycho-social model

If the Winch-inspired argument above is correct, the psychiatry, unlike, for example, quantum physics, has to keep one foot on the ground via a lay understanding of the norms governing mental illness, disorder, dysfunction and distress. That in turn has implications for paradigm shifts in psychiatry, given their connection to incommensurability. If, on the one hand, a future psychiatry maintains its links to the ordinary understanding of mental illness that currently sets the agenda for mental healthcare, then that ordinary understanding provides a bridge head for scientific understanding, undermining the very idea of there being a paradigm shift. If the Winchean argument is right, whilst psychiatry can go beyond ordinary agents’ understanding of the norms deviations from which amount to illness, it must still be rooted in it. If, on the other hand, a radical change in psychiatry severs those links, that might amount to a genuine paradigm shift for medical psychiatry - because that would imply a lack of the commensurability – then it would lose its identify as a response to mental illness and distress. It would no longer be psychiatry.

Consistent with this basic framework, there is one other possibility. The call for a paradigm shift may be intended not just to cover scientific psychiatric theorising about the causes of mental illnesses and distress – for example, a turn to more biological models and biomarkers – but also everyday conceptualisations of them. That is, it might be a kind of counsel of despair. On the assumption that everyday thinking about mental illness is essentially confused and raises insoluble conceptual questions of the sort expressed in the dilemma, ‘mad or bad?’, it might be thought that the rational response is a kind of conceptual radical overhaul. But given the consequences of a Kuhnian paradigm shift, such a move risks putting into an ungraspable future not merely elements of medical science but also a significant element of our self-understanding as agents, the basic norms governing actions, emotions, responsibility and free will.

If this working through of the combination of Kuhn and Winch is correct, then the wish for a paradigm shift in psychiatry seems doubly misplaced. First, the connection to incommensurability undermines the rationality of the wish even when limited to an area of medical science. Second, a change which did not sever the connection to the concepts we use to make sense of ourselves would not be a paradigm shift since the innovation would be merely partial leaving in place standards for rational assessment of the technical innovations. But a paradigm shift localised to psychiatry which rendered the pre- and the post-shift worldviews incommensurable would have to sever the connection to those grounding concepts and that could only be because psychiatry had lost its way. Finally, a paradigm shift of not only medical psychiatry but also of the everyday norms against which folk conceptions of illness, distress and suffering are measured is such a radical view that there is no way now to conceptualise what it is for which one would be wishing.

Against this long-standing inchoate wish for a paradigm shift in psychiatry, the bio-psycho-social model of psychiatry is a helpful reminder of its potential costs [Engel 1977]. Our understanding of mental illness is not merely rooted in biological natural science. It is much more broadly rooted in psychological and sociological basic norms and rules governing activity, thought and feeling. Genuine fundamental change in that whole conceptual package is not something to be lightly entertained.

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