Academic journal article East Asian Archives of Psychiatry

Profiling Mentally Ill Offenders in Hong Kong: A 5-Year Retrospective Review Study

Academic journal article East Asian Archives of Psychiatry

Profiling Mentally Ill Offenders in Hong Kong: A 5-Year Retrospective Review Study

Article excerpt


Prevalence of mental illness in incarcerated population

Forensic psychiatry involves assessment and treatment of people with mental disorders who come into the legal system.1-3 In the incarcerated population, psychiatric morbidity has been reported to be high in both remanded (63% of males and 76% of females) and sentenced (37% of males and 57% of females) prisoners.4-7 The estimated prevalence of severe mental illness in the incarcerated population has been reported to be 9% to 20%, compared with 6% in the general population.8-11 The increased prevalence is likely to be related to deinstitutionalisation, limited community resources, prominent court decisions and legislative rulings, and the 'revolving door' phenomenon.12,13 In a systematic review of 62 studies that included 23,000 prisoners from 12 countries, the prevalence of psychosis, major depression, and antisocial personality disorder was found to be several times higher in prisoners than in the general population.14

Relationship between crime and mental illness

The high prevalence of mental illness in remanded and sentenced populations could reflect the association between crime and mental illness (schizophrenia, personality disorder, depression, substance misuse, intellectual disability, and dementia). Patients with schizophrenia have been reported to be more likely to commit violent offences, although evidence on the association between schizophrenia and crime is conflicting.15 In a study in Sweden, the rate of violent offences was four times higher in schizophrenia patients, although the overall crime rate of male schizophrenia patients was similar to that of the general population.16 There is a strong association between acute psychotic symptoms and violence, and psychotic symptoms account for most of the very violent behaviour.17,18 In the Dunedin birth cohort, the violence rate among those with schizophrenia-spectrum disorders increases five-fold (in those with criminal convictions) to seven-fold (self-reported).19

In the United Kingdom, up to 78% of prisoners have a personality disorder, with antisocial personality disorder being the most common, followed by paranoid (in men) and borderline personality disorders (in women).20 In a systematic review of 62 studies about mental disorder in prisons, 65% of male prisoners had a personality disorder and 47% had a dissocial personality disorder.14

The typology of depressed shoplifters includes isolated young adults under stress and older people with chronic depression, depression associated with acute loss, and personality disorder with an aggressive swing.21,22 Similarly, shoplifting in middle-aged women is associated with depression and anxiety symptoms, particularly if shoplifting is the sole conviction.22

Substance misuse, combined with mental illness or personality disorder, is common among forensic psychiatric patients.20 Alcohol and drugs may be associated with criminal behaviour because intoxication can impair judgement and reduce inhibition. In withdrawal states, agitation and psychotic symptoms, such as paranoia, can predispose one to violent behaviour. Additionally, various forms of theft are committed to purchase illicit substances. Substance misuse is more prevalent in individuals with personality disorder, and alcohol misuse is associated with increased violence in people with antisocial personality disorder.23

A meta-analysis of sex offenders reported strong association between low intelligence and paedophilic sex offences, but not for other types of sex offences.24 A case series reported that 11% of those charged with arson had learning disability.25 In a retrospective review of 2397 patients in memory and ageing centre, the common manifestations of criminal behaviour in patients with frontotemporal dementia were theft, traffic violations, sexual advances, trespassing, and public urination, whereas patients with Alzheimer dementia commonly committed traffic violations. …

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