The British Journal of Psychiatry (2003) 182: s28-s31
© 2003 The Royal College of Psychiatrists
Diagnosis of personality disorders in learning disability*
REGI ALEXANDER, MRCPsych
Leicester Frith Hospital, Leicester LE3 9QF, UK
SHERVA COORAY, FRCPsych
Parkside NHS Trust, Kingsbury, UK
Correspondence: Dr Regi Alexander, Leicester Frith Hospital, Mansion House, Groby Road,
Leicester LE3 9QF, UK
Declaration of interest None.
* Paper presented at the second conference of the British and Irish Group for
the Study of Personality Disorders (BIGSPD), University of Leicester, UK, 31
January to 3 February 2001. 

ABSTRACT
Background Though contentious, the diagnosis of personality
disorders in persons with learning disability is clinically
relevant because
it affects many aspects of management.
Aims To examine published literature on the diagnosis of personality
disorders in learning disability.
Method Selective review with computerised (Medline, Embase and
PsychInfo) and manual literature searches.
Results The variation in the co-occurrence of personality disorder
in learning disability, with prevalence ranging from less than 1% to 91% in a
community setting and 22% to 92% in hospital settings, is very great and too
large to be explained by real differences.
Conclusions The diagnosis of personality disorders in learning
disability is complex and difficult, particularly in those with severe
disability. Developing consensus diagnostic criteria, specific for various
developmental levels, is one way forward. Such criteria may need to include
objective proxy measures such as behavioural observations and informant
accounts.

INTRODUCTION
The diagnosis of personality disorders is fraught with methodological,
clinical and ethical controversies (
Tyrer
et al, 1993). Although
these difficulties are more
evident in the context of learning
disability, their diagnosis is still
significant because it
may affect the patient's acceptance into community
placements
(
Reid & Ballinger,
1987), predict subsequent psychiatric
disorders
(
Goldberg et al,
1995), determine the rate of referrals
to psychiatric services
(
Khan et al, 1997)
and significantly
influence the mode of management
(
Hurley & Sovner, 1995;
Mavromatis, 2000;
Wilson, 2001). This selective
review will
examine published literature on the diagnosis of personality
disorders in learning disability.

METHOD
Selective review with computerised (Medline, Embase and PsychInfo)
and
manual literature searches of the past 30 years.

RESULTS
Problems in diagnosis
The key themes are listed below.
- In those with average ability, lasting personality characteristics develop
by adolescence. However, the developmental phase for personality
characteristics among people with learning disability should be longer
(Royal College of Psychiatrists,
2001).
- Communication problems, physical, sensory and behavioural disorders
associated with learning disability affect the ability to diagnose a
personality disorder (Khan et al,
1997). The diagnosis of personality disorders often requires
subjective information about thoughts and emotions, difficult to elicit in
those with severe degrees of learning disability. Consequently, a particular
pattern of behaviour diagnosed as personality disorder in those
with mild or moderate learning disability may be perceived as
behavioural disorder in those with severe or profound
disability.
- The criteria for several personality disorders assume a level of cognitive
ability which may be absent in those with learning disability. Dissocial
(Goldberg et al,
1995) and paranoid personality disorders are examples.
Difficulties in establishing concepts such as preoccupation with
unsubstantiated, conspiratorial explanations of events either immediate to the
patient or in the world at large in a group with significant cognitive
limitations are self-evident.
- Further problems include the lack of valid, reliable instruments
(Khan et al, 1997),
differences between ICD-10 (World Health
Organization, 1992) and DSMIV
(American Psychiatric Association,
1994), confusion of definition and different personality theories
(Goldberg et al,
1995) and the difficulty in distinguishing personality disorders
from late effects of childhood psychosis
(Corbett, 1979).
- People with learning disability often display behaviours that overlap with
features of some personality disorders.
Schizoid/anancastic personality disorder
Earlier studies (Craft,
1959) suggested that schizoid personalities were very common in
people with learning disability. A significant proportion of these may
actually have had autism (Deb &
Hunter, 1991). Autistic traits also overlap significantly with
features of anancastic personality disorder.
Emotionally unstable (borderline) personality disorder
Features of borderline personality disorder, such as self-injurious
behaviour, impulsivity and affective lability, occur commonly in learning
disability (Mavromatis, 2000).
Consequently, additional features should be sought before making this
diagnosis (Wilson, 2001). Affective disorders commonly found in learning disability also mimic features
of emotionally unstable personalities (Deb
& Hunter, 1991).
Dependent and anxious/avoidant personality disorder
The presence of realistic dependency needs
(Reid & Ballinger, 1987) means that several criteria underpinning the diagnosis of dependent and
anxious/avoidant personality disorders may be difficult to apply in learning
disability.
The ability to diagnose personality disorders, inclusive of all
sub-categories across the whole spectrum of learning disability, is hence
debatable. Reviews of the published research literature fail to provide
conclusive evidence.
Assessment/research instruments used
Instruments used in studies of personality disorders in learning disability
are described below.
Structured Assessment of Personality (SAP)
The SAP (Mann et al,
1981) relies on an informant account to establish a diagnosis of
personality disorder (Ballinger & Reid,
1987,
1988;
Reid & Ballinger, 1987).
The presence of three or more durable criteria establishes a personality
trait. If this causes significant personal distress, or occupational or social
impairment, the diagnosis of personality disorder is made.
Reiss screen and PIMRA
The Reiss screen is a screening tool for the detection of psychopathology
in mental retardation (Reiss,
1988). For those scoring above a threshold, the Psychopathology
Inventory for Mentally Retarded Adults (PIMRA;
Matson, 1988) is administered
(a checklist of psychopathological behaviour based on DSM-III).
Temporal-Lobe Personality Behaviour Inventory
This instrument is useful in identifying abnormal personalities
specifically associated with epilepsy (Bear
& Fedio, 1977).
Clinical diagnosis - ICD and DSM
Most studies have used clinical diagnoses based on either the
ICD or DSM systems to identify personality disorders. The standard categories
within these classificatory systems have sometimes been augmented with
additional items, e.g. Immature and Impulsive
(Corbett, 1979).
Diagnostic Criteria in Learning Disability (DC-LD)
Adopting a multi-axial, hierarchical approach to diagnosis, the DC-LD is a
new system providing operationalised criteria for psychiatric disorders in
adults with moderate to profound learning disabilities
(Royal College of Psychiatrists,
2001). The key points regarding personality disorders are
summarised below.
- The ICD-10 category of organic personality disorder should not be used
purely on the grounds that a person has a learning disability, or a learning
disabilities syndrome with an associated behavioural phenotype or
epilepsy.
- A higher age threshold (over 21 years) for diagnosing personality disorders
is advised.
- The categories of schizoid, dependent and anxious/avoidant personality
disorders are not recommended.
- The system emphasises that the diagnosis of personality disorders in severe
or profound learning disabilities is unlikely.
- The problem that these diagnostic criteria have not been primarily designed
for use with adults with learning disabilities who offend is noted.
- Initial diagnosis using the criteria for Personality Disorder - Unspecified
is suggested. If these are met, further sub-classification should be
considered.
There are no published studies using the DC-LD criteria for personality
disorders.
Studies with data on personality disorders in learning
disability
Many of these studies were designed to look not only at personality
disorders but also at any form of psychiatric morbidity in learning
disability. They vary widely in their methods and findings. The key studies
are summarised in Table 1.

DISCUSSION
Most of the earlier studies included patients drawn from the
whole range of
learning disability and did not distinguish
between personality and
behavioural disorders. Some suggested
that the diagnosis of personality
disorders was unrelated to
the level of intellectual disability
(
Corbett, 1979;
Eaton & Menolascino,
1982).
Others did report a relationship
- antisocial personality
disorders in those with mild learning
disability and explosive personality
disorders in those with
severe learning disability
(
Day, 1985).
The introduction of the Standardized Assessment of Personality (SAP;
Mann et al, 1981) was
a crucial development in research in this area. Although initial studies using
this instrument were limited to people with mild and moderate learning
disabilities (Reid & Ballinger,
1987; Deb & Hunter,
1991), it has subsequently been used across the whole range of
intellectual ability (Goldberg et
al, 1995; Khan et
al, 1997). Some of these studies revealed exceptionally high
prevalence rates of up to 90% for different types of personality disorders in
learning disability (Goldberg et
al, 1995).
The ultimate validity of any diagnosis is in its clinical usefulness. Not
surprisingly, therefore, unusually high prevalence rates would raise questions
regarding the usefulness of such a diagnosis, particularly in those with
severe or profound learning disabilities. Indeed, if diagnostic criteria are
applied in such a way that an over-whelming majority of those with learning
disability satisfy the criteria for personality disorders, it is not of much
clinical use, either for the management of the individual patient or the
planning of services.
Two recent studies have examined this issue further. In the first
(Naik et al, 2002),
those with a clinical diagnosis of personality disorder were identified and
ICD-10 (World Health Organization,
1992) criteria applied thereafter. The prevalence rate of 7% in
this study may well be an underestimate of the true prevalence, but
nevertheless succeeds in identifying a group of patients with specific care
needs and resource implications. The second study
(Flynn et al, 2002),
apart from estimating the prevalence rate, examined the diagnostic validity in
terms of an association with abusive experiences in early life. The authors
also introduce the concept of severe personality disorders and
suggest criteria for making this diagnosis. This is a novel approach in this
field and carries particular significance for the practising clinician.
The diagnosis of personality disorders across the whole spectrum of
learning disability is complex and difficult, particularly in those with
severe disability. In this context, the need for a personality typology based
on the developmental perspective has been highlighted
(Gostasson, 1987). Developing
consensus diagnostic criteria for each personality disorder, specific for
various developmental levels and including objective proxy measures such as
behavioural observations and informant accounts is one way forward.

Clinical Implications and Limitations
CLINICAL IMPLICATIONS
- Diagnosing personality disorders in those with learning disability is
clinically significant, but there are problems with diagnostic clarity.
- There is a need for consensus diagnostic criteria which use objective proxy
measures and are specific for different developmental levels.
- No accurate prevalence figures for personality disorder in learning
disability are available.
LIMITATIONS
- Because of a paucity of robust evidence-based studies within the field
there may be errors in interpretation of data.
- There have been differing views on what constitutes personality disorder in
learning disability over the past 20 years and this may have accounted for
some of the variation found.
- The diagnosis of personality disorder in severe learning difficulty is
extremely difficult to distinguish from the effects of the disability
alone.

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P. TYRER, C. DUGGAN, and J. COID
Ramifications of personality disorder in clinical practice
The British Journal of Psychiatry,
January 1, 2003;
182
(44):
s1 - s2.
[Full Text]
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