​Inclusive and reductive approaches to 'spectrum' disorders? Lumping or splitting?


There are many proponents for the breaking down of symptomatology and behaviour profiles of developmental disorders, such as Tourette Syndrome and autism (ASD/Asperger's), into discrete 'comorbid' disorders. This occurs less often in ASD than in TS and the more inclusive approach is reflected in the use of the word spectrum in ASD. However there is a move to reduce ASD to a core social/communication disorder but the latest incarnation of DSM (V) does finally include sensory processing deficits within the core difficulties of ASD. It should be noted that similar sensory issues are also common in TS. Despite this tendency, preferred by many psychiatrists/psychoanalysts and to a somewhat lesser extent, neurologists and neuroscientists, substantial evidence for the existence of multiple co-occuring comorbidity, in all cases, is yet to be established convincingly.

 

Clearly comorbidity can and does occur between disorders but can be assumed too readily if definitions are not concise or substantiated. As will be seen this is not just a matter of whether an 'expert' belongs to the lumpers or splitters movement/perspective, it is a matter of some importance both in the consequences for real life situations and from the standpoint of 'good' science which requires substantive evidence collected by credible data sampling. It is important to note that on average only 1 in 10 individuals with TS 'appear' to have just tics - although as diagnostic ability remains highly variable there is a good chance that the figure could actually be lower.

 

History-taking by physicians is often less than optimal in many cases and the 'right questions' often remain unasked and the ability to elicit clarifying responses from patients is sometimes relatively poor. History-taking, unfortunately, is dependent on the understanding and 'opinion' (or 'professional' perspective) of the enquirer. It is extraordinary how many physicians and psychologists are not sufficiently aware of the available literature on TS and current clinical research findings. The heated and continuing debate over the reliance of physicians on American DSM criteria and the methods by which they are determined shows little sign of reaching a consensus opinion that satisfies all. Many see these diagnostic criteria as overly simplistic (especially individuals with neuro-developmental conditions and parents of children affected), ill-conceived or unscientific and not representational of the majority of actual patient case histories. Patients themselves sometimes feel they are being stigmatised and stereotyped by labelling which doesn't fit their 'disorder' correctly and can lead to exclusion and prejudice. Others feel such criteria are 'driven' by potential drug therapies for separate 'disorders' and that the overall spectrum of their symptoms is not being addressed appropriately.



Symptoms and signs do not directly equate to disorders (a symptom is what a patient experiences, a sign is what a physician observes/elicits). Attention deficit is a symptom but cannot be (definitively) said to represent, or belong exclusively to, Attention Deficit Disorder (ADD) as there are other possible neurological or psychological (and environmental) mechanisms by which attention deficit may occur. Indeed many with TS would think it odd that anyone should imagine they didn't experience attention deficit as a consequence of their TS! Many 'disorders' are 'diagnosed' in a relatively subjective manner, using behavioural checklists and sometimes almost arbitrary fencing off or 'recognition' of perceived symptom groupings. It may not seem important that a person is diagnosed with an inclusive disorder in which the symptoms and behaviours are all seen as a manifestation of that disorder or whether a core disorder is diagnosed along with other separate comorbid disorders. However this does matter in many ways to the patient, their family and especially in terms of medical and other provision they may require. Although a core neuro-developmental disorder has been diagnosed, invariably, and for many disconcertingly, the comorbid disorders are defined as psychiatric. Taking a symptom and adding the word 'disorder' does not a disorder make! Nor does it account for symptoms that appear to be common to multiple disorders as with TS, ASD, OCD, ADD, ADHD, SPD etc. Underlying pathophysiological mechanisms are required and objective investigations to substantiate a diagnosis are desirable. In the case of TS there are yet no definitive genetic markers but many other modalities with potential exist, including neuro-imaging, neuro-hormonal chemistry and in some cases quantitative measurement of neurological signs. 



Non-medical professionals such as teachers, educational psychologists, speech and occupational therapists rely heavily on expert opinion and have built paradigms around specific 'disorders' and the assumed difficulties they represent and hence the ways in which they can be approached. Individuals, their parents and family want to be able to make sense of the diagnoses they have been given and increase their understanding also. Many find an 'alphabet soup' diagnosis of multiple disorders bewildering and confusing. Another concern, especially for Tourette Syndrome, is the disparity in clinical treatment response achieved when those comorbid disorders are treated (in isolation) compared to the responses expected in individuals without Tourette Syndrome with those disorders.



This diagnostic uncertainty and a paucity of underlying mechanisms to explain many of those 'disorders' also has profound consequences for research. Research involves establishing a model for a disorder and then designing data collection and analysis around already established diagnostic categories and criteria. Researchers work on the assumption that what they are looking for and quantifying is real. This breaks down when the diagnostic definitions and symptom-separation may be erroneous, artificial or poorly defined. If TS is perceived as an 'inclusive' spectrum disorder, symptoms, although variable and diverse, will mostly (excepting genuine comorbid symptomatology) be seen as intrinsic to that disorder and suggest appropriate directions for research and help in determining underlying mechanisms for a disorder of greater complexity. However if symptoms such as obsessive and compulsive thinking and behaviours are allocated to a separate disorder (OCD), attention deficit and hyperactivity are allocated to ADD/ADHD, low mood to an affective disorder (depression) or theory of mind difficulties to autism, then clearly the approach will differ markedly. There is much research on TS, OCD, ADD, SPD and ASD, however the boundaries are not as distinct as one might imagine and symptom patterns may be blurred as a number of characteristic symptoms are shared between disorders.



Whether an inclusive (spectrum) or comorbidity (reductive) approach is taken for defining and understanding the symptoms and behaviours of Tourette Syndrome, it is essential that an awareness is achieved of the full range and expression of possible symptoms and behaviours. Many parents of children with a diagnosis are often left without knowing what to expect or why certain behaviours are occurring or whether other children and parents have experienced those issues. In a nutshell, there needs to be an awareness and understanding of the full spectrum of Tourette Syndrome. Parents are frequently informed that one behaviour belongs to Tourette Syndrome but another does not, often without sufficient explanation or worse due to insufficient knowledge on the part of the expert consulted. Evidence-based reasoning should always be preferred to an over-use of professional 'authority' - good professionals will sometimes say "I don't know" and hopefully "I will find out for you" or refer you to someone with more experience or expertise.



In an educational setting or from the equality or legal standpoint, it is essential that professionals such as teachers, family practitioners, educational psychologists, occupational therapists and also social welfare officers, know the actual range of difficulties or educational needs that might be expected in an individual with Tourette syndrome, ASD etc. Frequently such key professionals have understandings that range from "TS is just tics" or "autism is just a social communication impairment" (reductive/splitting approach) to an awareness of the full spectral range of the disorder that can present in an individual (e.g including for TS or ASD: sensory hypersensitivity, attention deficit, theory of mind difficulties, reading/writing difficulties, obsessive thinking, literality, sleep disturbance, emotional reactivity and so on). The latter inclusive understanding enables better or more appropriate and tailored, and hence beneficial provision to be put in place.



Not knowing the 'true' presentation of Tourette Syndrome is a common difficulty for many physicians, therapists, scientists and the public in general. There is some friction between those who have or live with the disorder and the professional 'experts' who differ widely in their understanding, insight and interpretation. One thing that is certain is that people with TS feel that experts rarely fully understand what the disorder entails and fail to have sufficient insight regarding the 'existential' and self-pervading nature of TS. It is often felt that simplistic and reductionistic explanations are given that do not concur with actual experience. Science and (medical practice) should always strive to be evidence-based but concern is being expressed that too few professionals are familiar with the current available literature and thinking and that uncertainties and errors of definition (especially in diagnostic definition) are undermining the value of research.



Tourette Syndrome is not a 'new' disorder and was described in detail more than a century ago. There is a substantial volume of scientific, clinical and biographical literature but what is lacking is a synthesis. This is, in part, due to a long hiatus in objective study of TS during the rise (and subsequent decline) of the Freudian 'psychoanalytically' aligned school of psychiatry which diverged from more 'neurologically' orientated research and clinical approaches that previously prevailed. This paucity of objective research on Tourette Syndrome, during the first half of the 20th Century, was addressed by the pioneering work of researchers and physicians such as Dr Arthur Shapiro and others during the 1960s and has led to increased interest, better diagnosis and for 'less intractable' cases effective treatment options.

 

Understanding of the neuro-anatomical underpinning of TS has advanced and some promising results are being obtained from neuro-endocrine, genetic and recently computer-aided imaging studies. For cases in which tics have been hitherto intractable to available treatments, Deep Brain stimulation (DBS) now provides patients with a neuro-surgical approach, reserved for symptoms severe enough to have a substantial impact on quality of life.

 

Evaluation of behavioural approaches (HRT, CBT, CBIT, counselling and social and educational support) that help patients compensate for their symptoms and adapt to the challenges they experience, shows encouraging results are being achieved for various TS symptom domains as an alternative to pharmaceutical therapy alone. Improved long-term treatment responses and patient-perceived quality of life improvements have been demonstrated for tics, obsessive-compulsive symptoms, anxiety and low mood in many with TS while avoiding the potential side-effects of medication that can be significant in some.

TS - Inclusive/reductive Approaches