Prevalence of personality disorders in a special hospital population

Frequencies of personality disorder categories as defined by the Millon Clinical Multiaxial Inventory were determined in a sample of male mentally disordered offenders detained in a maximum security hospital (N = 115). Sixtyeight per cent of the sample met criteria for at least one personality disorder, and only 12 per cent displayed an absence of deviant personality traits. Most prominent were dependent, avoidant, schizoid, and histrionic and passive-aggressive disorders, while compulsive, borderline and antisocial disorders had a low frequency While patients in the Mental Health Act category of psychopathic disorder were more likely to show passive-aggressive disorder, and to exhibit a higher frequency of some features of antisocial personality disorder than those categorized as mentally ill, the frequency of personality disorders in these two categories was otherwise not significantly different. The results suggest that the medico-legal categorization is not a useful guide to the long-term psychological problems and treatment needs of this population.