Monday, 31 August 2015

Rethinking Therapist Drift

One of the strangest ways I have ever been evaluated in my career was while delivering a psychological intervention in a prison. My job was to stand in front of a room of young offenders and facilitate group discussions of their "thinking skills". The prison service has a clear idea of what this should look like, indeed so clear that every session I did was filmed. Auditors could then check that I was sticking to the protocol. 

This remarkable surveillance was an attempt to minimize what is commonly called "therapist drift", the process whereby a therapist ostensibly delivering an evidence-based therapy winds up doing something else instead. Psychotherapies are not easy things to administer, and in the face of diverse people and problems it's easy to see how one might end up straying from the guidelines outlined in therapy delivery manuals. But if you claim to be doing, say CBT when you aren't in fact doing anything of the sort, you might not get the same results.

For the most part, therapist drift is regarded as a bad thing. This makes sense (at least, it's internally consistent). Drift is a problem for people who are trying to research a therapy (because they don't end up testing what they intend to) and it's potentially a problem for people who are trying to deliver a therapy (because rather than delivering something that has been demonstrated to be effective, they do something which is not).

But there is a strand of thought in clinical psychology and psychotherapy that maintains suspicion about the notions of "adherence" and "drift", and of evidence-based therapy altogether. Critics of this stripe view evidence-based-approaches as overly rigid and formulaic, too focused on technique at the expense of relationship. There is some good quality criticism of manualized therapy (here's a good example), but also much exaggeration about manualized therapies making the process "robotic" (as though a set of instructive principles were incompatible with being human). 

Recently I looked into the topic (in a very non-systematic way) to see what research had found about the importance of adherence and drift. Most studies that have been done (and it is surprising how few there are that focus specifically on drift) seem to support the contention that "drifting" can lead to less impressive outcomes. However, one study had an intriguing result.

Examining CBT for panic disorder, researchers (Jonathan Huppert and colleagues) took measures of patient motivation (rated by the therapists) and adherence to the therapy manual (rated by listening to audiotapes of sessions). Perhaps counter-intuitively, the researchers found that among highly motivated patients, the therapist adherence did not have much impact on outcome (look at the graph and you can see the blue line only slopes upward a small amount; this difference was not found to be significant). However, among less motivated patients, adherence was associated with worse outcomes than drift.*

One possible explanation for this (one that Huppert and colleagues themselves suggest) is that patients with low motivation present an extra degree of complexity which cannot be adequately addressed by staying within the set protocol. An experienced therapist will depart from the standard protocol to address in some way the low motivation, before continuing with the planned process. Under this interpretation, the therapists who show the greater adherence with the "low-motivation" patients are paradoxically failing to do something with the low adherence therapists are succeeding at it. Although they are moving beyond the purview of the manual, it seems misguided to call this "drift". This squares with the extended discussion by Drew Westen and colleagues on the more tendentious implications of therapy manuals:

...manualization commits researchers to an assumption that is only appropriate for a limited range of treatments, namely that therapy is something done to a patient—a process in which the therapist applies interventions— rather than a transactional process in which patient and therapist collaborate. (p.639)

And yet still some idea of therapist "drift" seems important. Unless we believe there is no value to specific training for psychologists and psychotherapists, we want to have some reasonably defined sense of what we're up to; some sense of what it looks like to do the job properly. It is any deviation from this that can reasonably be considered drift. In other words: in the space between conforming, robot-like, to a predetermined protocol and doing whatever the hell you want, there lies a knowable range of skills which we ideally would want to adhere to. That set of skills is what constitutes being a good psychologist. This definition extends the realm of evidence based practice some way beyond the parameters of individual evidence based treatments. 

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*Though the authors note: "it is important to keep in mind that even when therapists were rated as less adherent, adherence was still rated as “good” or better, suggesting that therapists did not cease doing CBT for panic, but likely incorporated other strategies into their armamentarium" p.202

Friday, 24 July 2015

Why does "schizophrenia" persist?

I sometimes wonder if anyone in mental health really believes in the idea of an illness called schizophrenia. Sure there are true believers in psychiatry like Jeffrey Lieberman and E.F. Torrey who will happily claim that there is a distinct brain disease the word connotes. Their advocacy (such as in Lieberman's recent "Shrinks" and Torrey's ever popular family manual "Surviving Schizophrenia") is a big part of how the diagnosis has come to have broad currency.

But once you get interested in schizophrenia, it doesn't take long for the whole edifice to look a bit crumbly. For almost as long as schizophrenia has been around there has been contention about it as an entity. This contention is not just an expression of "phenomenologic relativism" (Lieberman's angry charge), it is a respectable doubt about whether the construct of schizophrenia is a valid object for scientific study. It has been articulated most elegantly by Richard Bentall and Mary Boyle, who both conclude that schizophrenia is not a valid construct. When you try to find examples of people refuting their position, it's hard to come up with much of substance. Thus, a chapter on the construct of schizophrenia in Daniel Weinberger's big textbook on schizophrenia says this:
The diagnostic criteria currently used (ICD - 10 and DSM - IV - TR) can be considered provisional and arbitrary constructs with some face validity that meet the objective of facilitating international communication and research. (p.9)
Meanwhile, in their Very Short Introduction to Schizophrenia, Chris Frith and Eve Johnstone acknowledge Mary Boyle's long and detailed book, but they dismiss it by saying simply "we are not convinced" (this comment appears in a Further Reading section at the back of their book).

Given all the articulate doubt, and its less than convincing refutation, why has the schizophrenia label survived? When this question has been asked by critically minded scholars, the answer has tended to be "money and professional esteem". David Pilgrim endorses a version of this argument in an essay in "Reconstructing Schizophrenia", and in "Madness in Civilization", Andrew Scull points out that "chronic conditions are chronically profitable" (p.393).

There can be no doubt that the financial and professional interests of psychiatry and pharmaceutical companies play a role in the survival of schizophrenia, but this explanation cannot be the whole story. Both motivations played a role in the brief flurry of interest in Paediatric Bipolar Disorder (an ugly controversy documented well in multiple posts by One Boring Old Man), but the APA, cogent of its many problems, ultimately moved to stop that diagnosis getting into DSM-5. That is not proof that the APA's mechanisms for self regulation are good enough, but it does suggest the need for another ingredient in order for a disorder to become as successful as schizophrenia.

What is missing in the economic account of schizophrenia's survival is the fact that, validity concerns notwithstanding, there is a way in which the diagnosis is very convincing; on the face of it many people who meet criteria for schizophrenia seem to be seriously unwell and many of them will testify to that fact. This is something that schizophrenia's many critics frequently seem to miss. It is largely (though not entirely) missing from the BPS's Understanding Psychosis document, and it is missing from the writing of Bentall, Boyle, and others, who tend to view their work as a foundation for moving away from an "illness model" of what they refer to as "psychological distress".

In fact, even the ultimate collapse of schizophrenia would not be tantamount to evidence that there are no illnesses in the space the diagnosis used to occupy. In a staunchly critical book "Schizophrenia is a Misdiagnosis", the psychiatrist C.Raymond Lake argues that schizophrenia cannot be distinguished from severe psychotic mood disorders, and also provides a long list of disorders which can get diagnosed as schizophrenia (see below).



Perhaps then the persistence of schizophrenia can partly be attributed to a case of a divided opposition. All of schizophrenia's critics can be seen as wanting to carve away chunks from the existing construct by placing people into alternative categories. For some these chunks are "psycho-social distress" (i.e. not ill at all), for others they should go into more precise medical categories (i.e. ill with something doctors actually understand). To some extent these players in the debate speak at cross purposes; they might even be construed as competing over territory:
Schizophrenia as shrinking territory.

By far the most vocal and high profile critics are psychologists who want to reframe schizophrenia as a form of psychosocial distress (they want to expand the purple section in the diagram). This effort is unlikely to be entirely successful because, even with skepticism about the DSM construct, many people's intuitions are that there is something illnessy about the experiences which commonly attract the diagnosis. This group tends to be reluctant to acknowledge the presence of any psychiatric illness (witness the BPS report-writing guidelines which sought to exclude even the words "illness" or "disorder").

Schizophrenia's medical critics believe that progress will come as more and more people currently in the "bucket" of schizophrenia are given a correct medical or psychiatric diagnosis (as the yellow section expands). This quieter territory expansion is constantly ongoing, with new "subgroups" of schizophrenia emerging periodically, associated with specific physiological characteristics (a very recent example is here). When these subgroups are sufficiently well understood they raise an interesting problem; are they still a form of schizophrenia, or (given that the DSM definition of schizophrenia has an exclusion clause saying that symptoms must not be due to the direct physiological effects of a [...] general medical condition.) have they become something else?

It is this ongoing uncertainty which surely accounts for the continued plausibility of schizophrenia in the psychiatric and public imaginations. Yes there are many people who fall in the purple and yellow overlaps of my venn diagram, but there are others (how many?) who currently do not. The hypothetical construct schizophrenia is a testament to the suspicion that, when everything tumbles out, there will be a well understood bio-psycho-social process giving rise to the symptoms in DSM-5. Should that process be sufficiently well understood, it might be what we end up giving the name "schizophrenia" 100 years from now.

Alternatively, the purple and yellow sections may keep expanding, finally squeezing schizophrenia out of the picture altogether. Only an omniscient being can currently say how much of the middle circle will be left in the end. For the time being no amount of political activity seems sufficient to quell people's suspicion that when psychiatry talks about schizophrenia, it is talking about something worth naming. 

Tuesday, 14 July 2015

Medicating History

The history of the discovery of neuroleptic drugs for psychosis is often (more often than not?) used for professional-political ends. I recently read Jeffrey Lieberman's book on the history of psychiatry, in which he provides a description of the first psychiatric use of chlorpromazine. If you take it at face value you get the impression that the new drug was immediately impressive because of its dramatic impact on the symptoms of psychosis per se. Here's Lieberman's description (with some underlining of parts I found particularly striking):
On January 19, 1952, chlorpromazine was administered to Jacques L., a highly agitated twenty four- year-old psychotic prone to violence. Following the drug’s intravenous administration, Jacques rapidly settled down and became calm. After three steady weeks on chlorpromazine, Jacques carried out all his normal activities. He even played an entire game of bridge. He responded so well, in fact, that his flabbergasted physicians discharged him from the hospital. It was nothing short of miraculous: A drug had seemingly wiped away the psychotic symptoms of an unmanageable patient and enabled him to leave the hospital and return to the community. (p.164)
Compare that to a 2007 piece by Thomas Ban, which is sufficiently similar that it could have provided the model for Lieberman's description, but for a few subtle differences (again with extra underlining):
Jacques Lh., a 24-year-old severely agitated psychotic (manic) male was the first psychiatric patient to receive CPZ; he was administered 50 mg of the drug, intravenously, at 10 am, on January 19, 1952. The calming effect of CPZ was immediate but since it lasted only a few hours several  treatments were required before the patient’s agitation was controlled. Repeated administration of the drug caused venous irritation and perivenous infiltration. Hence, on several occasions barbiturates and electroshock were substituted for CPZ. Nonetheless, after 20 days of treatment, with a total of 855 mg of CPZ, the patient was ready “to resume normal life.” (p.496)
It's amazing how word choice and subtleties of description can paint radically different pictures of the same set of events. I know nothing else about Jacques L/Lh. What were the nature of his psychotic symptoms? To what extent was he actually manic? Was it psychosis, mania or his agitation that was most affected by the chlorpromazine? Finally, what happened to Jacques, and what did he think of the new medication he had tried?

Thursday, 2 July 2015

The Pleasures of Delusion

Would it be somehow crass or offensive to talk more about pleasure when we talk about clinical delusions? We tend to think of delusions (defined now in the DSM-5 as "fixed beliefs that are not amenable to change") as being principally aversive experiences, and so they seem to be. The idea that you are being persecuted, that you might die imminently, that your family have been replaced by imposters; these are all terrifying sounding notions. Apart from being frightening in content, delusions have the added misery of rarely being shared. If everyone else believes you are being persecuted too, at least you don't have to deal with the profound disorientation of never being taken seriously.

But despite the undoubted terror of holding certain beliefs, and the loneliness of being the only person you know who does, it would be hard to imagine anyone ever having them if there wasn't something about them that we sometimes needed.

And in fact we have become accustomed to thinking of delusions as a defence, that is as being at least preferable to something worse. For Freud they were elaborate ways of getting away from homosexual longings. You start with a forbidden love, and how you go about denying it determines what sort of delusion you end up with. Freud accounted for delusions of persecution (”I do not love him I hate him” gets projected to “he hates me”), "Erotomania" (”I do not love him I love her”), delusions of jealousy ("it is not I who love the man, she loves the man") and megalomania ("I do not love at all-I don’t love anyone”). So systematic was Freud that his equation hung around for close to a century (and still holds sway in some quarters).

More recently delusions have been construed as one way of managing negative emotions. An individual who tends to attribute experiences to the external rather than internal realm, the argument goes, may be interpret feelings of badness in terms of a persecutory world rather than as being about themselves. There is a whole family of theories which take issue with this "attributional" account of delusions. These tend to invoke multiple factors, including most frequently perceptual anomalies and some sort of over-hasty style of reasoning. However even less emotion centric theories seem to gesture toward a motivational component. Thus the famous "jumping to conclusions" bias (the tendency, to make a decision on the grounds of less evidence), which seems fairly robustly associated with delusional ideation, has been itself accounted for in multiple ways. Is it a response to a "need for closure", or of an "intolerance of uncertainty"?

In a related vein, the philosopher Lisa Botolotti recently suggested that delusional beliefs could represent a sort of epistemic damage limitation. Better that you entertain a single false belief than suffer a broader psychic overwhelm and become unable to believe anything. This is the delusion as adaptive, as the fuse which can be allowed to blow in order to stop the whole edifice burning down. What these accounts all share is the suggestion that delusions are the least worst of several bad options. Put it that way and we focus on the unpleasantness of what is being defended against, but what about the appeal of holding a delusional belief?  It begs the question of what role our everyday beliefs hold for us. Hang around delusions research for long enough and you start to ask why anyone believes anything.

This is what brings me to the question of pleasure. Think of how pleasurable it is when you know the answer and no-one else does, when you finally figure it out, when everything suddenly makes sense. Addressing herself to the difficult question of what constitutes a satisfactory explanation, psychologist Alison Gopnik described "explanation as orgasm". Think, she suggests, of the way children (those "little scientists") seek endlessly for explanations, would they really be doing that if it wasn't a lot of fun? Richard Feynman spoke about "The pleasure of finding things out". As a research physicist, Feynman really was in the process of "finding things out", but don't the rest of us get pleasure from thinking we understand things better than we do? Anyone who has spent time in a bar with some politically disgruntled bore will recognise the peculiar glee that accompanies the "conspiratorial whisper". It is the pleasure of seeing through it all; of knowing what other people don't know. Might delusions sometimes afford something of that pleasure?

Sunday, 31 May 2015

Shrinks to Fit

Jeffrey Lieberman is gaining attention and opprobrium as he publicizes his new history of psychiatry "Shrinks". The book turns out to be a lively run through of the standard history-of-psychiatry over the last two centuries, though at first it's hard to know what to make of it. "Shrinks" initially reads as either the gentle reflections of a well intentioned psychiatric patrician, or a cynical attempt to skirt fascinating conceptual difficulties in the service of professional power. Which you pick depends on how much Machiavellian intent one imputes to its author.

Jeffrey Lieberman (very possibly the only psychiatrist 
alive who still wears a white coat).

In writing Shrinks, Lieberman does not just want to spin interesting yarns. There is an argument being made, and it explicitly invokes a narrative of progress. Psychiatry, according to Shrinks, has muddled through the Freudian intellectual backwaters of the 1950s and 60s; endured the clunking horrors of insulin coma and psychosurgery, and now it stands on the brink of a new scientific era. I might be missing something but this story strikes me as anything but "untold". It's a well worn and, I would argue, simplistic narrative which won't gain any traction among anyone even vaguely acquainted with the legitimacy crisis faced by psychiatry's classification system. You do not need to be one of Lieberman's "anti-movement" (I am not) to find passages like this a little too slick:
“For the first time in its long and notorious history, psychiatry can offer scientific, humane, and effective treatments to those suffering from mental illness. I became president of the American Psychiatric Association at a historic turning point in my profession. As I write this, psychiatry is finally taking its rightful place in the medical community after a long sojourn in the scientific wilderness.” (p.10)
That is not to say the book is not fascinating. For one thing Lieberman's prominence as a psychiatric researcher has given him front row seats for many of the major changes in psychiatry since the 1970s. He gives compelling accounts of the renegade neo-Kraepelinians gathering in St. Louis (far from the psychoanalytic powerhouse of New York) to assemble the "chinese menu" DSM-III which changed Lieberman's profession forever (entirely for the better by his account).

Lieberman also has some provocative personal perspectives on the broad debates concerning psychiatry, suggesting (on the basis of a conversation with E.F. Torrey) that R.D. Laing lost his argumentative lustre when his daughter started to suffer from a psychosis that was diagnosed as schizophrenia. Meanwhile, Thomas Szasz, "who I met several times [...] made it pretty clear he understood that schizophrenia qualified as a true brain disease, but he was never going to say so publicly" (p.113). He also peppers the book with clinical encounters, so we learn that Lieberman once gave ECT to the wife of a New York restaurant owner who was so happy with the results that he offered Lieberman free meals whenever he wanted.

We are also given to suspect that Lieberman harbours deep frustration with psychoanalytic dogmatism, and he concurs with Freud, who once muttered darkly to Jung that they were "bringing the plague to America". Lieberman writes like someone who endured a feeling of disconnection from his profession when he was starting out:
"If a trainee wanted to rise within the ranks of academic psychiatry or develop a successful practice, she had to demonstrate fealty to psychoanalytic theory. If not, she risked being banished to working in the public-hospital sector, which usually meant a state mental institution. If you were looking for an indoctrination method to foster a particular ideology within a profession, you probably couldn’t do much better than forcing all job applicants to undergo confessional psychotherapy with a therapist inquisitor already committed to the ideology.” (p.77)
However, he is no Freud-basher, calling the latter a “tragic visionary far ahead of his time" and suggesting that psychoanalysis remains the best way of understanding certain sorts of psychological problem (though this comes early in the book, and is soon buried by his aversion). Like Tom Burns in 2013's "Our Necessary Shadow" Lieberman has a story about helping a patient overcome an apparent conversion hysteria, lending weight to Freud and Breuer's early formulations of that fascinating disorder. He even mounts a rather good defence of Freud's approach to drawing empirical inferences from clinical data:
"Freud had no tangible evidence whatsoever of the existence of the unconscious or neurosis or any of his psychoanalytical ideas; he formulated his theory entirely from inferences derived from his patients’ behaviors. This may seem unscientific, though such methods are really no different from those used by astrophysicists positing the existence of dark matter, a hypothetical form of invisible matter scattered throughout the universe. As I write this, nobody has ever observed or even detected dark matter, but cosmologists realize that they can’t make sense of the movements and structure of the observable universe without invoking some mysterious, indiscernible stuff quietly influencing everything we can see." (p.43)
But Shrinks, like the proverbial psychoanalytic patient, might be most revealing where it least intends to be. This book is full of peculiar sentences whose brusqueness may reveal a studious irony or unfortunate lack of reflection:
“After watching shocked pigs become oblivious to the butcher’s knife, Cerletti decided that shooting 100 volts of electricity through a person’s skull was worth the obvious risks.” (p.167)
"While the publication of the DSM-III had been marked by tumult and controversy, the release of the DSM-IV was as routine and uneventful as the opening of a Starbucks." (p.271)
The breezy glibness on ECT, combined with the terribly unfortunate analogy between the DSM project and an oft-maligned international coffee chain, might have been calculated to provoke the dismay of the very people Lieberman seems keenest to convert. But then, perhaps it's just that Lieberman thinks he can best connect with a readership in modern corporate America. Just look at how he describes Freud's approach to leadership:

"If Freud was the CEO of the psychoanalytical movement, his management style was more like that of Steve Jobs than of Bill Gates." (p.54)
Baffling!

In a penultimate chapter on the creation of DSM-5, Lieberman sounds touchingly hurt by all the outrage the manual provoked (he puts it down largely to the Internet, and appears to lament the loss of a time psychiatry could go about its business in private), but puzzingly unwilling to acknowledge what was driving it. Detractors are either antipsychiatrists (Gary Greenberg) or purveyors of "epistemic hubris" (Thomas Insel). Only the DSM-5, for Lieberman, achieves the theoretical pluralism which must be psychiatry's future. Such pluralism is a noble goal for a discipline as wide ranging as psychiatry, but Lieberman is too sanguine about the ways that notorious "bible" (Lieberman favours "bible", a term I normally associate with critics) stifles rather than promotes it.

"Shrinks" is an entertaining read, and at least in some regards more nuanced than I expected. But Lieberman's unwillingness to wade into the conceptual confusions his specialty is still dealing with, combined with his true-believer optimism about its imminent brave new world (genetic tests for forms of psychosis; cognitive behavioural therapy apps), make for an all too smooth ride. This is a work of unabashed advocacy, even propaganda, and should be read as such.

-------------------------------------------------------

Postscript:

After writing this, I found a wonderfully scathing review of the book by Rebecca Twersky-Kengmana, who draws out more of Lieberman's weird disdain for psychoanalysis. More than me she views Lieberman's position on it as a flat contradiction. Her post also includes some great Amazon reviews by people dismayed at the quality of Lieberman's historical scholarship:

Shrinks: The Untold Story of Jeffrey Lieberman's Oedipal Victory Over Papa Freud

Friday, 15 May 2015

Spare Me the Sanctimonious Bleating About Trigger Warnings

The New Republic is carrying an article by Jerry Coyne lamenting the rise of the trigger warning, and specifically the idea that college literature courses should consider applying them to the Western canon. Without much explanation, Coyne links trigger warnings to the "decline in free speech at American universities". It is not clear exactly what a trigger warning prevents one from saying.

He is particularly concerned about an article by Columbia University's Multicultural Awareness Advisory Board that had appeared in that college's paper. It described a student's distress after reading rape scenes in Metamorphosis (which had triggered memories of her own experience of sexual assault) and being dismissed by the teacher. Evidently unable to suppress his own sympathy, Coyne hedges about the specific case:


There is something gloriously stupid about this. Coyne seems to be trying to have it both ways: "I would have provided a trigger warning to this student, but I would never have been so crass as to say the words 'trigger warning'". This is a familiar reactionary tic, driven by the same pig headedness that detests political correctness for its requirement that people don't always spew the first offensive crap that jumps into their heads.

Having concluded that trigger warnings per se are not that bad a thing after all. Coyne could have stopped after four paragraphs, allowing us to agree that warning people about potential personal sensitivities is hardly an attack on the first amendment. Instead he spends the rest of the article talking about how much he hates them.

Coyne trenchantly enumerates all the great works of literature that no-one will be allowed to read anymore (probably) if trigger warning Fascism (and he does use the word Fascism) takes hold. The Bible sanctions rape; Huckleberry Finn is full of racism and Anne Frank's Diary contains antisemitism. Perhaps there's an argument in there somewhere, but Coyne lost sight of it long ago. His article becomes an ill tempered rant about other people's sensitivity, culminating in a weirdly defiant account of his trip to Auschwitz.


Should everyone go to Auschwitz? Perhaps. I should certainly go, but what about people whose parents died there? Or survivors who remember it just fine thankyou very much? Unlike Coyne (whose appetite for understanding the worst in people is laudatory), some people don't need a reminder that ordinary people are capable of brutal things.

"Life" as Coyne says "is triggering". Nobody denies as much, but what the trigger warning sensibility acknowledges is that it is not always triggering for everyone to the same degree. Some of us (Coyne is clearly one) can blithely ignore the warnings. Others can be grateful that they increasingly get a choice about whether to follow link that may lead them to get lumbered with flashbacks to their own sexual assault, accident or suicide attempt. 

These sorts of consideration can be managed entirely without any impact on freedom speech; the inclusion of a brief parenthetical "TW" next to links or items on a syllabus is all it takes. If that offends you (and being offended by trigger warnings themselves is infinitely more obtuse than being offended by violence, sexism or racism) then you can simply refer to the content in advance as Coyne helpfully suggests. It's easy. 

Thursday, 14 May 2015

Pushing Explanations

Clinicians of my temperament get worried about forcing our explanatory views on the people with whom we work. Whatever explanatory frameworks we may have encountered during our training (medical, cognitive, psychodynamic models), however helpful we may have found them, we have a basic reluctance about regarding them as the explanation, and are more comfortable drawing on the idiom an individual uses to explain their life. One way to accommodate this kind of reluctance is to adapt a form of explanatory pluralism, where multiple models are held in mind, sitting comfortably alongside one another.

This approach is useful because it not only allows us to think in terms of multiple philosophical models, but also leaves space for the language used naturally by individuals whose experiences we are trying to discuss.

Much of the time this approach is relatively trouble free. That is to say, most of the time there is no benefit in substantially disagreeing with a person about how they account for their experience (I am thinking of an individual I knew who heard voices and was perfectly clear there was nothing wrong; who was I to disagree?) .

However, despite my basic sympathy with explanatory pluralism (what I could call my conviction that, when it comes to talk of "mental illness" there is basically no fact of the matter) I realise that I can cook up some uncomfortable cases for myself, which make the approach less satisfactory. Sometimes simply going along with an individual's account of themselves won't be sufficient.

Here is one problem case:
A parent approaches you, the clinician. Their child is causing problems at school. These are not insubstantial problems. The child is disruptive and, on the face of it, unpleasant to teachers and making it difficult for the classroom learning to proceed. You do a school visit and discover things are just as bad as you were told. The teachers are at their wits end. The parent knows the nature of the problem and implores you to help by providing an official diagnosis: according to them the child has a disorder called ADHD and your help is needed. If you can test the child and affirm that yes, they do meet the criteria for ADHD, you can ensure necessary accommodations at school. The child is absolutely certain too, that they have ADHD. They feel like they are not in control of themselves, that they are not to blame for the trouble they are caught up in, that a "disorder" is the only possible explanation. 
You are uncomfortable. Yes the child meets the DSM criteria for ADHD, but you worry about this construal. You note that the child has recently had to deal with some life events which anyone would find emotionally disruptive (let's say a close relative recently died, or they moved school, or they are being bullied). You have a sense that if the family system was able to address this emotional disruption in some way (with help from a systemically inclined clinician for example), the "ADHD" might be substantially resolved. Further, you have worries about the use of the diagnosis ADHD. Sure you could oblige and diagnose, but you feel if you do that then the parent will be less inclined to view the child's problems in a way that might be helpful. In short, you feel it is incumbent upon you to try and discourage them from the explanatory framework (my child has a disorder) that they have adopted. This is not because you think they are straightforwardly wrong (you can see their point) but because you think their metaphor will encourage damaging courses of action like the prescription of avoidable stimulant drugs and the neglect of the child's emotional life. 
Here's another:
An individual you know lives in the community. They have suffered several episodes of disorganization and confusion before and these have tended to lead to dangerous and self destructive behaviour. At best the individual has had sustained periods of self-neglect. Now they are becoming disorganized again. You are worried about them. If they could be persuaded to allow themselves to be looked after (temporarily in a caring inpatient respite center you could refer them to) then they would be safe while they recovered. But although they are frightened they do not feel they need any extra care as there is nothing the matter. As far as they are concerned they are fine.
You disagree. You feel they are being overcome by some psychological change, that they are becoming unwell. You don't buy a "chemical imbalance" theory of their problems, but you can see they are not themselves, and the idea that they have succumbed to an illness would be a useful metaphor. You don't think they will always have this illness, nor be defined by this illness, but that characterisation seems a powerful way of accounting for the need they now have for extra care. 
What both of these stories have in common is a narrative brought to bear on them by the people whose lives they primarily concern. The acquiescent part of you wants to go along with these stories (they are the account that makes most sense to the person), but a concerned part of you does not. Let's not take away the easy way out; the optimistic proposal that you can always construct a joint understanding. In both these cases the person resists your interpretation, some degree of conflict is unavoidable. Even without saying the other person is "wrong", you are trying to give life to an explanatory framework which is at odds with their view of how their situation is functioning. In these cases, are you doing something beneficent or are you enacting a failure of mutual understanding? I would suggest the former. Helpful though it is to try and adopt language that "makes sense" to an individual, it won't always fit with our best image to how to help people.