Dual diagnosis of personality disorder and severe mental illness is an important clinical association that has been under-researched with regard to clinical management.

To compare the outcomes of differenttreatment models.

The outcome of patients with this combined diagnosis was compared in a systematic review of three randomised controlled trials in which different forms of community outreach treatment or intensive case management were compared with standard care.

The results from the three studies showed that the outcome of comorbid diagnoses was worse than that of single diagnoses. Although assertive approaches reduced in-patient care, they sometimes did so at the expense of increasing social dysfunction and behavioural disturbance.

For those with comorbid severe mental illness and personality disorder, the policy of assertive outreach and care in community settings may be inappropriate for both public and patients unless modified to take account of the special needs of this group.

A major short coming of current research into personality is its failure to explore the relationship between theories of general personality and mental disorder.

To provide preliminary data to address this deficit.

In the first of two studies, we examined the relationship between the Neuroticism, Extraversion and Other – Five-Factor Inventory (NEO–FFI) and DSM personality disorders in a consecutive series of mentally disordered offenders. In the second, we sought to separate the personality dimension neuroticism from symptoms of depressive disorder in a sample of subjects with current depression.

Factors from the NEO–FFI were associated with different personality disorders in a predictable manner (first study). It was possible to identify a component of neuroticism (i.e. ‘worry’) that could be separated from depressive symptoms (second study).

Theories of general personality theory can enlighten and refine descriptions of abnormal mental states by informing both their aetiology and their prognosis.