Rep36 Understanding Personality Disorder

References

---

Key points:
I
Research suggests that about ten per cent of
community samples have problems that
would meet the diagnostic criteria for
personality disorder.
I
In primary care, research has suggested that
between 5 per cent and 8 per cent of patients
have personality disorder as their main
clinical diagnosis, although estimates rise to
between 29 per cent and 33 per cent when
all clinical diagnoses are considered and not
just the primary diagnosis.
I
Research suggests that 30 per cent to 40 per
cent of psychiatric outpatients and between
40 per cent and 50 per cent of psychiatric
inpatients are believed to meet the criteria
for one or more personality disorders;
estimates vary considerably, however, and
some studies have suggested prevalence rates
among psychiatric outpatients that are in
excess of 80 per cent.
I
Between 50 per cent and 78 per cent of adult
prisoners are believed to meet criteria for
one or more personality disorders, and even
higher prevalence estimates have been
reported among young offenders.
I
Research has suggested that as many as two
thirds of male mentally disordered offenders
have one or more personality disorders. This
estimate may be higher among women in
forensic psychiatric settings.
I
Some types of offending behaviour may be
associated with personality disorder although
an assessment of the full range of
criminogenic or risk factors, which may or may
not include personality disorder, is required
to adequately formulate offending risk.
1.2.1 How common are personality 
disorders in the general population?
The prevalence of personality disorders in
community samples has not been investigated
with the same vigour as the prevalence of other
psychiatric conditions (Casey, 2000; Mattia &
Zimmerman, 2001). From the research that has
been conducted over the last twenty or so years,
findings suggest a lifetime prevalence of any
single personality disorder in community
samples of between 6.7 per cent and 33.1 per
cent, with a median prevalence across studies of
12.9 per cent (Mattia & Zimmerman, 2001).
Other research, based on more stringent
diagnostic criteria, suggests more conservative
lifetime prevalence estimates, of between 6.7 per
cent (Lenzenweger 
et al
., 1997) and 9.4 per cent
(Maier 
et al
., 1995). The lifetime prevalence of
individual personality disorders ranges from one
per cent to three per cent, with paranoid,
histrionic and obsessive-compulsive diagnoses
occurring most frequently. 
Personality disorders tend to co-occur with
other Axis I disorders. Maier et al (1995)
reported that almost two thirds of individuals
with a personality disorder diagnosis also had a
diagnosis of an Axis I disorder. Swanson 
et al
.
(1994) reported that in a sample of individuals
who had a diagnosis of antisocial personality
disorder, in excess of 90 per cent had a co-
occurring diagnosis of any Axis I disorder, mainly
alcohol abuse or dependence. Personality
disorders appear to be more prevalent in younger
compared with older people (Zimmerman &
Coryell, 1989), and the association with gender is
equivocal although the prevalence of any
personality disorder appears to be comparable
between men and women (Maier 
et al
., 1992). 
In primary care settings, abnormalities of
personality are the primary clinical diagnosis for
approximately five per cent to eight per cent of
patients who have any conspicuous mental
health needs (Casey, 2000). Personality
difficulties in primary care settings appear more
prevalent among men than women. However,
when assessments are carried out on all patients
irrespective of primary diagnosis and structured
forms of personality disorder assessment are
used, prevalence estimates tend to rise several-
fold. For example, Casey 
et al
. (1984) carried out
a study of personality in every patient who had
conspicuous mental health needs in an urban
general practice. The authors reported that
personality disorder was the primary diagnosis in
between 6.4 per cent and 8.9 per cent of the
sample, but when all diagnoses were considered,
it was noted that just over a third of the entire
sample had a diagnosis of a personality disorder.
Similarly, Moran 
et al
. (1999) examined the
prevalence of personality disorder in 303
individuals attending primary care settings.
These authors reported a prevalence of 29 per
cent for any personality disorder in their sample,
and found that Cluster B personality disorders
were particularly likely to be associated with
psychiatric morbidity. 
In psychiatric in- or outpatient settings, the
prevalence of personality disorders are thought
to be higher still. Between 30 per cent and 40
per cent of outpatients and between 40 per cent
and 50 per cent of psychiatric inpatients are
thought to meet the criteria for a personality