Is the loss of Axis II a loss?

The move away from a multi-axial nosological model for bothmajor classifications in psychiatry appears, on first impression,to have merit. There is little fundamental evidence to suggest thatpersonality disorders are separate from other mental disorders andthere is no doubt that they overlap.1 Like other mental disorders,personality disorders have a heritable component that accountsfor longitudinal stability and changes in mental state related toenvironmental stress.2 Geneenvironment interactions shapepersonality disorder over time in a similar manner to other mentalstate disorders.3 Furthermore, there is some evidence that allpsychopathology shares underlying similar factors, regardless ofdiagnostic label.4 Why then should personality and the possibilityof personality disorder be considered separately?

There is no doubt that the placement of personality disorderon a separate axis stimulated consideration of personality inclinical assessment and in research. The past three decades haveseen a dramatic rise in the literature focusing on personalitydisorder, particularly borderline and antisocial personalitydisorder.5 There has also been a bourgeoning of clinical trials ofinterventions in patients with personality disorder, again mostlyfocused on borderline personality disorder.6 Related to this is theincreasing recognition that personality disorder is not a diagnosisof exclusion from clinical services. These research and clinical out-comes are arguably related to the development of a nosologicalsystem with a separate specifier for personality disorder.

The differences between personalityand mental state disorder

It can also be argued that if personality disorder is categorised as amental state disorder, this may obscure differences that are

clinically important. Most obviously, personality facets, traits orcharacteristics, however described, are present more or lesspersistently throughout the life course and personality disorderis best conceptualised as extremes of these facets leading tofunctional and societal impairment. This differs from most mentalstate disorders, in which persistence may be common but whichhave clearer onset and end. The underlying structure of personalitydisorder can usually be identified in childhood and adolescence(despite reluctance to make diagnosis early) and the essentialfeatures may be present as early as 3 years old with some prognosticcapacity.7 Personality disorder is best conceived using a diathesismodel, as a condition that is always present but may often beclinically quiescent for long periods without ever losing itsessential elements.2 Furthermore, the nature of stability andchange in personality through the life course is increasingly beingunderstood. This allows for recognition of extremes of personalitydisturbance at differing stages in life. Personality disorderobviously interacts with mental state disorder and may predisposeto it or impair clinical course8 but is not part of the sameconstruct. This understanding is supported by increasing evidencethat the course of mental disorders may differ in the presence orabsence of a personality disorder. Since we have failed to findneurobiological differences that explain these differing courses ofillness it may be better to focus on the personality componentrather than the mental illness one.

Clinical implications of the lossof the multi-axial system

In busy clinical settings cross-sectional assessment of symptomsfollowed by instigation of treatment is the primary focus.Personality disorder, diagnosed as a cross-sectional polytheticconstruct (as it is described in DSM-5),9 is unlikely to beprioritised over mental state disorder. However, when consideredalongside mental state disorders, personality pathology may playan important role in diagnosis and management, and theadditional time needed to undertake a personality assessmentmay pay off in the long run. Patients may have worse outcomesif it is ignored. The diagnosis of personality disorders remains astigmatised one even among mental health professionals10 and itis likely to become more hidden if it is diagnosed on the same axisas other mental disorders.

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Diagnostic neglect: the potential impactof losing a separate axis for personalitydisorderGiles Newton-Howes, Roger Mulder and Peter Tyrer

SummaryBoth major classifications in psychiatry have now movedaway from the multi-axial nosological model. This is clinicallyunderstandable as the specific categorical diagnoses,other than borderline personality disorder and personalitydisorder NOS (not otherwise specified) were so seldomused and empirical evidence would not support thepolythetic categorical system. As a consequence, thosewith personality disorders, frequently referred to as Axis II

disorders, now have to compete with all other mentaldisorders for clinical attention.

Declaration of interestNone.

Copyright and usageB The Royal College of Psychiatrists 2015.

The British Journal of Psychiatry (2015)206, 355356. doi: 10.1192/bjp.bp.114.155259

Editorial

Giles Newton-Howes is a senior lecturer in the department of psychologicalmedicine, University of Otago, Wellington, New Zealand, and an honorarysenior lecturer in the department of psychological medicine, Imperial CollegeLondon, UK. His research interests include the impact of personality in mentalstate disorders and the outcomes of personality disorders. Roger Mulder is aprofessor at the Department of Psychological Medicine University of Otago,Christchurch, New Zealand, and Peter Tyrer is Professor of CommunityPsychiatry at Imperial College London, and an honorary consultant psychiatristat the Central North West London Mental Health Foundation Trust, London, UK.

A possible reason for the confusion between personalitypathology and mental state disorders may be related to theunempirical categorical personality disorder diagnoses in bothDSM-5 and ICD-10.11 By setting clear, if unvalidated, operationalcriteria for individual categories of personality disorder in DSM,the clinician has been tempted to choose one or the other ratherthan embracing both. The removal of these categories in theproposed ICD-11 classification12 in favour of a single axis ofseverity makes the classification more attuned to a separate axis.These categories lack scientific accuracy and clinically imply thatpersonality disorders are just types of mental disorders with setsof symptoms and specific behaviours that are identified usingstrict operational definitions. If these personality disorderdiagnoses were indeed valid descriptions of personality pathology,then removal of Axis II would seem a sensible way forward.

However, evidence does not support this. Most of thecategorical personality disorders are rarely diagnosed and poorlyresearched, with borderline personality disorder and antisocialpersonality disorder overshadowing all other personality disorderdiagnoses. This in turn reinforces an oversimplified view ofpersonality disorder creating a false impression that antisocialpersonality disorder is a diagnosis in forensic settings and border-line personality disorder a synonym for recurrent self-harm. Suchdiagnoses ignore the underlying traits that are the constantfeatures of personality, the influence of these traits in mental statedisorders and the usefulness of identifying personality pathologyin children, adolescents and older age patients.

Whats in a name?

In considering the nosology of mental and behavioural disordersthe terms Axis I and Axis II increasingly have become terms todescribe categories such as depression, schizophrenia, anxietydisorders, borderline personality disorder and antisocialpersonality disorder as though they were similar entities. The termserious mental illness encapsulates all diagnoses, includingpersonality disorders and does not adequately discriminate AxisI and Axis II disorders. How then can we capture the notion ofpersonality disorder as separate from other mental disorder in ascientific and clinically meaningful way?

We are not advocating a return to DSM-IV13 with Axis I mentalstate categorical disorders and Axis II personality categoricaldisorders described as though they were similar entities that couldbe comorbid with each other. Instead, we argue that the termsmental state disorder and personality disorder are useful clinicalconstructs that allow a different perspective to be taken for thesetwo psychopathologies. Such an approach allows for the recognitionof development in the science of personality pathology, best seenas a unitary dimensional construct with multiple phenotypes. Italso provides a useful nosology for clinicians and researchers.

Although the decision of the DSM and ICD classificationnot to use multi-axial systems has some merit, if the negativeimplications for personality disorder are not identified andaddressed there may be negative clinical consequences for patients.There is a significant danger that clinicians will rarely address theimpact of personality pathology in psychiatric patients. Since allpsychiatric disorders are now diagnosed on a single axis it isunlikely that an Axis II will be re-introduced and we do notnecessarily advocate for that. We support the concept thatpersonality pathology will be addressed as a secondary diagnosiswhere possible.

We would argue that clinicians should consider mental statedisorder and personality disorders in all patients. This may stillbe possible if the current Axis I like categories of personality

disorder are replaced by a dimensional descriptive model thatcould be used with all patients. The new ICD-11 classificationsystem proposes that all categories of personality disorders arereplaced by a single dimension of personality dysfunction atvarying levels of severity.12 (A similar proposal for DSM-5 wasrejected and relegated to Section III emerging measures andmodels.) Such a model recognises that change in personalitypathology occurs and allows personality status to be repeatedlyassessed as a secondary diagnosis.

The importance of the impact of personality disorder on thelong-term outcomes of mental illness is increasingly recognised.We are concerned that personality disorder may become a lessimportant component of the clinical diagnosis in psychiatryresulting in a loss of important clinical information. Personalitypathology incorporates a longitudinal developmental view ofpsychopathology and should be considered alongside mental statesymptoms, intellectual functioning, neuropsychological functionsand social deprivation in all patients presenting with mentaldisorders.

Giles Newton-Howes, MRCPsych, FRANZCP, Department of PsychologicalMedicine, University of Otago, Wellington, New Zealand; Roger Mulder, MBChB,PhD, FRANZCP, Department of Psychological Medicine, University of Otago,Christchurch, New Zealand; Peter Tyrer, MD, FRCPsych, FMedSci, Centre for MentalHealth, Imperial College London, UK

Correspondence: Giles Newton-Howes, University of Otago, Departmentof Psychological Medicine, Otago University, PO Box 7343, Wellington,New Zealand. Email: giles.newton-howes@otago.ac.nz

First received 24 Jul 2014, final revision 18 Nov 2014, accepted 2 Dec 2014

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