Department of Psychiatry of Disability, St George's Hospital Medical School, London
Correspondence: Andrew Flynn, Mental Health of Learning Disabilities, Oxleas NHS Trust, c/o 183 Lodge Hill, Goldie Leigh, Abbey Wood, London SE2 0AY, UK
Declaration of interest Support from Partnerships in Care.
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ABSTRACT |
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Aims To investigate the prevalence of personality disorder in adults with learning disability who are in specialist challenging behaviour in-patient services and to examine the validity of the diagnosis of personality disorder in this group in terms of its association with abusive experience in early life.
Method The Standardised Assessment of Personality (SAP) was used to diagnose personality disorder in 36 individuals with mild/moderate learning disability. Case notes were reviewed for details of clinical diagnosis and early psychosocial history.
Results Thirty-nine per cent of the sample met the criteria for severe personality disorder. This diagnosis showed a significant association with early traumatic experience.
Conclusions Severe personality disorder is a common diagnosis in this group. There is preliminary evidence that the diagnosis is associated with abuse in childhood.
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INTRODUCTION |
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METHOD |
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The responsible psychiatrist for each service identified all individuals with mild or moderate learning disability who had no clinical contraindication for research participation. Individuals were recruited if they gave informed consent and could identify an informant who had known them well over the previous 5 years.
Instruments and data collection
The Standardised Assessment of Personality (SAP;
Pilgrim et al, 1990)
is a semi-structured diagnostic interview. Ballinger & Reid
(1987) have shown it to have
satisfactory interrater reliability when used with people with learning
disabilities in an institutional setting. It is administered by a trained
interviewer to an informant who has at least 5 years of acquaintance with the
participant. The interview generates ICD-10
(World Health Organization,
1992) diagnoses of personality disorder. The guidance recommends
that where more than one category can be assigned, the most
disabling should be rated alone. However, because of the preliminary
nature of this study and the desire to avoid unnecessary subjectivity, in
cases where multiple diagnoses were made, each was accorded equal rank.
Case notes were reviewed by the principal investigator (A.F.) for clinical diagnoses and histories of childhood abuse or neglect. Although this judgement was largely subjective, instances had to be associated with a child protection response by social services. These reviews were carried out blind to the results of SAP ratings.
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RESULTS |
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The SAP diagnoses of personality disorder could be assigned in 34/36 (92%) of cases. Co-occurrence of personality disorder categories was common, with a mean of 3.4 per person (range 0-8). The frequencies of personality disorder diagnoses, as derived from the SAP, are shown in Table 1.
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Personality disorder and early traumatic experience
It was hypothesised that if personality disorder is a valid diagnosis in
learning disability, then it should show some evidence of an association with
a known aetiological factor. Severe psychosocial adversity in childhood
(especially physical and sexual abuse) is an acknowledged risk factor for
antisocial, borderline and histrionic personality disorder in people without
learning disability. These diagnoses frequently co-occur and, following their
study of an in-patient psychotherapy service for people referred with clinical
diagnoses of predominantly borderline personality disorder, Dolan et
al (1995) suggested that
severity (referring to breadth of psychopathology) may be more
relevant than individual categories. Owing to the high frequency of multiple
SAP diagnoses in the study population, this concept of severity was used for
further analysis.
When the case notes of the 36 participants were examined, documentation of childhood abuse was found in 11 cases. These represented instances where it was considered that most mental health professionals would regard the events recorded as unequivocally abusive. For example, one participant had been sexually abused repeatedly by his father and members of the extended family. The perpetrators subsequently were prosecuted. Another had been taken into care as a consequence of physical abuse and evidence of gross physical and emotional neglect.
Odds ratios of prior exposure to early trauma were calculated against two possible adult outcomes: receiving a clinician diagnosis of personality disorder (antisocial, emotionally unstable or histrionic) and a SAP-derived diagnosis of severe personality disorder. For the latter, an arbitrary cut-off was chosen for severity: participants with five or more personality disorder diagnoses were rated as having severe personality disorder. This threshold was decided upon prior to data analysis and 14 participants were rated as having severe personality disorder (38% of the sample). The results are shown in Table 2.
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Overlap of clinician and SAP diagnoses of personality disorder
Overall, 14 individuals were rated as having severe personality disorder
with the SAP. Only five of these had been diagnosed by their psychiatrist as
having a personality disorder of any type. In no case where a clinical
diagnosis of personality disorder was recorded was more than one category
assigned.
Of the other nine individuals, four were diagnosed with a psychotic illness, two with an affective disorder and two with a pervasive developmental disorder (autistic continuum disorder). One of the severe group had received a clinical diagnosis of organic personality disorder. In terms of the validating criterion of early traumatic experience, two of the individuals diagnosed with psychosis, one of those with pervasive developmental disorder, and the person with organic personality disorder had been exposed to abuse when young.
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DISCUSSION |
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Prevalence of personality disorder and the utility of the SAP
The finding that 19/36 participants (53%) could be diagnosed with dissocial
personality disorder and 18/36 (50%) with emotionally unstable personality
disorder is remarkably in keeping with Ballinger & Reid's
(1987) conclusion that 50% of
their hospital population had the broadly equivalent explosive
personality disorder (according to the older ICD-9 categories in use at
the time; World Health Organization,
1978). This is a slightly larger group than the 38% with severe
personality disorder because a minority of these individuals did not exceed
the severity threshold. From the point of view of methodology, this finding is
encouraging. However, it needs to be considered in the context of several
issues concerning the diagnosis of personality disorder in this population
using the SAP.
There have been only a handful of published systematic studies of personality disorder in learning disability. In the first of these, Ballinger & Reid (1987) recommended the use of the SAP because it had acceptable interrater reliability in their setting and avoided the problem of subjects with severe communication impairments having to complete self-report questionnaires or take part in unmodified structured interviews. Subsequent work by these and other investigators have used the same assessment method and the SAP seems to have acquired the status of industry standard. This means that it is reasonably easy to compare the outcomes of different studies but there is the obvious drawback that there have been no serious efforts to compare the SAP's performance in learning disability with schedules taking other perspectives on personality construction or to modify the use of these methods for this group.
Finally, it may be that the SAP itself deserves some modification to preserve its construct validity. For example, it was hard for informants to make confident inferences about complex cognitive constructs such as continual feelings of emptiness (item 2 in the criteria for borderline personality disorder) in people who may not have the ability to formulate and communicate such an idea for themselves. Interpreting the threshold for crossing from personality accentuation to disorder also can be problematic: some informants found it understandably difficult to separate the occupational or social impairments secondary to learning disability from those related to personality dysfunction.
Diagnosis of personality disorder and experience of childhood
abuse
Despite acceptance of the SAP as an important diagnostic instrument in
learning disability research, there have been no studies of its validity (and,
by extension, the validity of the diagnosis of personality disorder itself) in
this group. With this in mind, the study took the opportunity to look at the
possible relevance of exposure to psychological trauma to the development of
personality disorder in adults with learning disability.
Psychosocial adversity, especially exposure to abuse, in early life is an important risk factor for severe personality disorder in adult life in the general population (Herman et al, 1989). Similarly adversity is common in people with learning disabilities but there have been few attempts systematically to relate experiences of abuse to challenging behaviour, and none to formal psychiatric diagnoses. The calculated odds ratios suggest that, whether diagnosed by clinician or research questionnaire, some presentations of personality disorder in people with mild to moderate learning disabilities share the same risk of prior exposure to early psychosocial adversity.
The magnitude of the risk is uncertain, with the small sample size leading to large confidence intervals. However, the association certainly seems more robust for severe personality disorder diagnosed by the SAP than it does for the clinical diagnosis of personality disorder. Unfortunately, the overlap of large confidence intervals prevents any definitive conclusion. The possibility of a trend in odds ratio of 13.3 v. 6.3 may give a tentative nod to Dolan et al's (1995) suggestion that breadth of psychopathology is a meaningful idea. At any rate, it does not undermine our strategy of recording multiple diagnoses and stratifying the sample into severe and mild/moderate.
It must be emphasised also that the definition of early trauma was not more closely defined at this stage. It was felt to be premature to narrow abuse down to specific categories, in view of the study's preliminary nature and its hypothesis-generating intention. It relied on the principal investigator's subjective judgement that some clear-cut event that had at least prompted action by social services had occurred. However, this judgement was made blind to the SAP diagnosis. There are important ethical constraints on pursuing abuse histories for research purposes in learning disability and it is hoped that these results will make it justifiable to pursue this line more systematically in our group in the future. An initial step would be to map developmental trajectories to adult disorder using qualitative methods.
Research versus clinical diagnosis
The discrepancy between clinical and research diagnoses is interesting. One
might conclude that it represents a case of misdiagnosis by clinicians,
especially if the result diagnosis looks more valid in terms of
exposure to a particular causative factor. However, other standards of
validity exist that are, arguably, more relevant to clinical practice,
especially response to treatment and prognosis. Also, it may be that
clinicians have deeper reservations about diagnosing personality disorder. For
example, some have doubts that it is appropriate to make the diagnosis at all
in those with severe and profound learning disability
(Gostason, 1985), although
others have discussed cases of narcissistic personality disorder in people
with IQs of less than 20 (Goldberg et
al, 1995). Furthermore, there may be concern, made explicit
by one psychiatrist whose patients were surveyed in this study, that
diagnosing personality disorder implied untreatability and its
connotations were prejudicial in identifying community placements for hospital
residents.
Implications of validity studies in learning disability
Although the association observed here requires confirmation through more
rigorous investigation, its demonstration in terms of linkage to a specific
diagnosis has important implications. People with learning disabilities are
generally excluded from mainstream mental health research. Although this may
be partly owing to concerns about capacity to consent, there remains an
assumption that behavioural and emotional problems are either organically
mediated or environmentally contingent. This is reflected in approaches to
challenging behaviour emphasising the symptomatic use of
medication, behavioural intervention or both
(Emerson, 1995). Recognition
that many examples of challenging behaviour are expressions of psychiatric
conditions such as psychosis or affective disorder has given a rationale for
the use of psychotropic drugs but, importantly, has permitted people with
learning disabilities to have access to mainstream treatments.
This is a core principle underlying the practice of specialist learning
disability psychiatry.
However, it is only recently that access to psychotherapy, especially for traumatised individuals, has become an issue (Hollins & Sinason, 2000). Psychotherapy is of particular relevance to personality disorder, in various forms, because it constitutes the only intervention with any degree of evidence-based efficacy (e.g. Menzies et al, 1993). This does not mean to say that psychotherapy is appropriate for all adults with learning disabilities who have diagnosable personality disorder, but then neither is it appropriate for all those cases where learning disability is not involved. It does mean that psychotherapies for some adults with lifelong histories of severely challenging behaviour should be a priority for health service research with a view to future service development.
Demonstrating the validity of personality disorder may serve a wider purpose. Personality disorder research and clinical practice has come to focus particularly on psychotherapy and related themes. Biological, behavioural and, to some extent, social models have received less attention. In a recent review of neuropsychiatric perspectives on personality disorder, Fogel & Ratey (1995) point out that of all psychiatric diagnoses, disorders of personality are most likely to be seen as functional. Akiskal (1981) has suggested that many cases of severe personality disorder can be seen as presentations of organically mediated affective disorders, but misdiagnosis has denied access to effective pharmacotherapy (or even any service at all). More recently, Linehan et al (1993) have shown that behavioural principles can underpin effective therapy for women with borderline personality disorder. Paris (1996) offers an important theory of personality disorder in biosocial terms, showing how symptoms can be seen to serve a function in terms of the interaction between the individual and his or her social environment.
Many specialist clinicians in the field of learning disabilities will point out that they have been successfully applying these ideas for some time but have done so under the guise of challenging behaviour rather than personality disorder. It is notable therefore that some important concepts more usually associated with learning disability research have been used to investigate aspects of severe personality disorder. An example is Blair et al's proposal (1996) that aspects of antisocial personality disorder reflect a failure in the ability to develop theory of mind, an aspect of cognitive psychology that has played a major part in understanding autism. It may turn out to be the case that general psychiatry can learn from the problems faced by adults with learning disabilities, but one needs to know where to look.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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REFERENCES |
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Received for publication July 10, 2001. Revision received January 14, 2002. Accepted for publication January 17, 2002.