by Evan Yacoub, Consultant Psychiatrist, Brothers of Charity Galway, Woodlands Centre, Renmore, Co Galway.


The recent Winterbourne Scandal in the UK (Department of Health 2012) is a reminder of the importance of designing, commissioning and providing services which give people with intellectual disabilities the support they need close to home, and which are in line with well established best practice.

Like other people in society, people with intellectual disability sometimes commit criminal offences. This article reviews the background literature and outlines how to develop services for offenders with an intellectual disability.


What is offending behaviour?
Holland et al. have reviewed the issues associated with defining ‘criminal offending’ in relation to people with Intellectual disabilities (Holland et al. 2002). Identifying illegal behaviour or consequence is one aspect. However, it may also be important to establish if there was intent to perform the act or to bring about its consequences. For people with intellectual disabilities, it can be a major issue to decide whether there was intent, and expert evidence can be called to help determine this. Do ‘offenders’ with intellectual disability always know what they were doing, or what the consequences of their actions might be?

Prevalence of offending in people with intellectual disabilities
Hodgins (1992) probably performed the best study of the prevalence of offending in people with intellectual disabilities. She looked at convictions for a Swedish birth cohort of over 15,000 people born in Stockholm in the same year who were followed up for 30 years. She concluded that men with an intellectual disability (identified through attending special classes) were 3 times more likely to be convicted than men without intellectual disability, and women with an intellectual disability were four times more likely to be convicted than women without intellectual disability.

The extent to which higher conviction rates in people with intellectual disability result from differences in arrest (caused for example by intellectually disabled offenders being less able to evade the police) rather than differences in offending is unclear (Robertson 1988). Simpson and Hogg (2001) comment that the prevalence of offending among people with Intellectual disabilities, compared with the general population, is impossible to assess firmly on the available information, and that further research is required.

Baron et al. (2001) found that intellectually disabled offenders start offending at an early age, that they frequently have a history of multiple offences, and that sex offending and arson are over-represented offence types. The latter finding has been replicated in other studies, although Simpson and Hogg reported that it was in clients with borderline intellectual functioning (IQs of 71-84), rather than intellectual disability, where this over-representation took place.

Coid (1988), in a retrospective study of 362 men remanded to a UK Prison for psychiatric reports, found that approximately 10% had a learning disability. Rack (2005) notes that ‘20% of the prison population have some form of hidden disability which will affect and undermine their performance in both education and work settings.’

Female offenders with intellectual disabilities
A study of the characteristics of a cohort of female patients referred to a forensic intellectual disability service (Lindsay et al. 2004) found that:
■ Females constitute 9% of referrals to the service.
■ The history of sexual abuse (61%) in the cohort of female offenders is higher than in male cohorts, but (at 38.5%) physical abuse is no higher than in appropriate comparison groups.
■ Identification of mental illness is high at 67%.
■ Total re-offending over 5 years was 22%, but excluding prostitution it was only 16.5%.

It was concluded that in some respects, this cohort of female offenders shows similar characteristics to their male counterparts. However, there are higher levels of mental illness, higher levels of sexual abuse and lower levels of re-offending. It was hypothesised that because females constitute such a low percentage of referrals, it suggests that women with intellectual disabilities do not show the same levels of sexually abusive behaviour or aggressive behaviour—the two most frequent reasons for male referral. Therefore, an intervening variable such as mental illness may indeed be a significant factor. Lower re-offending rates may indicate the success of interventions directed at psychological problems and mental illness.

Forensic intellectual disability psychiatry

Johnston and Halstead (2000) described the practice of forensic psychiatry in the intellectually disabled population as having distinct but subtle differences from general forensic and mental health services, and as a blend of the philosophies and styles of two cultures. They point out that the literature base for forensic intellectual disability remains sparse, and that low prevalence rates, low research funds for this minority group, ethical research restrictions, and the diversity of service provision have militated against large-scale surveys of this offender population. They also raise the dilemma that many behaviours have been regarded as ‘challenging’, rather than ‘forensic’, although there may be little difference in the severity of the resultant interpersonal or property damage.

Although the evidence base in this subspecialty is expanding, it remains relatively small, particularly in terms of robust randomised controlled trials.

Secure intellectual disability services
Many offenders with intellectual disabilities have been judged to require institutional care outside the prison system, and have been looked after in secure institutions. In England, from the mid-1970s it was recognised that in addition to high security hospitals and prisons, there was a need for more local, medium-secure care for some offenders with intellectual disabilities (Home Office and Department of Health and Social Services 1975). This has gradually been implemented, although the development of special secure services for offenders with intellectual disability has been uneven (Chiswick and Cope, 1995). In more recent times, much of the provision has been in the independent sector, i.e. not directly provided by the state-run health service (Yacoub et al. 2008).

One needs assessment of a regionally defined group of intellectually disabled forensic patients found them to be a heterogeneous group with wide-ranging psychiatric needs (Crossland et al. 2005). The majority were cared for outside their geographical area of origin, either in specialist state-run facilities or the independent sector. Those with an additional diagnosis of mental illness were most likely to be detained in state facilities within the region: a diagnosis of personality disorder was associated with placement in either a high-secure setting or the independent sector.

This needs assessment also found that individuals with a clinical diagnosis of intellectual disability (who were male, and had no additional diagnosis) were most likely to be detained in services provided by specialist intellectual disability/mental health trusts out of area. There was a small group of women, who were all placed outside the region. Offending behaviour was most likely to consist of violence against the person, sexual offences and arson. The majority assessed were felt to have long-term needs. The study raised important implications for future provision of forensic services in the area, particularly the need to offer services with treatment programmes tailored to the needs of the population under review.

Identification within the criminal justice system
The ‘No One Knows’ programme by the Prison Reform Trust (2007) found that the identification of people with intellectual disability within the criminal justice system and their diversion out of it are issues which need to be addressed. The report makes a number of recommendations for the assessment of people with intellectual disability by police officers:
■ A system should be introduced across all police forces for screening suspects for vulnerability, to include identification of difficulties associated with communication and comprehension. Training for custody officers on how to undertake the screening must also be put in place.
■ All forces should provide training for all officers, and particularly custody officers, on methods of presenting the caution and legal rights with maximum clarity. For example, officers can be taught to present the caution sentence by sentence, if there is any doubt about the suspect’s comprehension. Officers should also be encouraged to test suspects’ understanding of the caution and legal rights routinely.

Community services for offenders with intellectual disabilities
Services for people with intellectual disabilities in Ireland, as in the UK, look to support people in the least restrictive environment possible, and with modern models of community care, such as day opportunities and activities, supported housing and living, and person-centred planning (National Federation of Voluntary Bodies 2009).

Community forensic teams in the UK which are present in some regions would typically have the following members:
■ A team manager, often from a nursing or social work background
■ Community nurses
■ Social workers
■ A consultant psychiatrist and a junior psychiatrist
■ A clinical psychologist.

Potential sources of referral include community teams, and those referred through the criminal justice system (such as the probation service and the courts). Another important source is people being discharged from local secure units, many of whom may still be subject to mental health legislation.

Patients likely to benefit from the specialist expertise of a community forensic team for people with intellectual disability include
■ Those with complex needs, often including challenging behaviour and/or substance misuse.
■ A serious and ongoing risk of violence, sexually inappropriate behaviour, or other harm to others.

Craig et al. (2006) showed that offenders with intellectual disability can be engaged psychologically in the community, as well as within secure settings. One of the challenges for secure intellectual disability services is liaising with community services in order to ensure that discharges are not delayed, and that they are safe. This is much easier to implement if secure services are local (Jacoub et al. 2008).

Regarding offence-specific treatment in the community, Lindsay and Smith (2006) compared the responses to treatment of sex offenders with intellectual disability receiving different length probationary sentences. The group treatment addressed issues of: denial, minimisation and responsibility for the offence; harm done to the victim; behaviour consistent with offending; and victim awareness and confidentiality. The subjects were assessed on a standard questionnaire designed to assess attitudes consistent with sex offending. There was a significant difference between the groups at the end of the probation period, with subjects sentenced to 2 years’ probation showing greater improvement. The authors recommend that a court order for a one-year period of probation with treatment is of little value when dealing with sex offenders with intellectual disability.

There is some information on prognosis for people discharged from specialist units. A follow-up study looking at long-term outcomes for people with intellectual disabilities discharged from a medium-secure service found that, although challenging behaviours resembling the original offence continued, reconviction rates were low at only 11% (Alexander et al. 2006).

Services in Ireland

In 2004 the National Intellectual Disability Database (NIDD) recorded 25,416 individuals with an intellectual disability in Ireland (Department of Health and Children 2006). However, not everybody with a mild intellectual disability is included in the database.

Most of the mental health services for people with intellectual disability are provided by the voluntary and non-statutory sector (e.g. by religious orders, parents associations, etc.). The voluntary sector has largely determined the shape of intellectual disability services. Service-level agreements are negotiated between the HSE and voluntary agencies to provide services for those with intellectual disability. Multidisciplinary teams in intellectual disability services exist and focus on social, vocational, educational and residential needs of the individual, but in general they do not deal with specialist mental health needs.

For people in residential care, mental health care is supported by a relatively small number of intellectual disability psychiatrists. Where service users can be supported where they are living, severe challenging behaviour and forensic needs are managed in the community by the MDTs within the services. Vision for change also reported that significant numbers of Irish prisoners have an intellectual disability.

Historically, people with intellectual disability requiring inpatient secure care were sent to the UK. There are currently no forensic intellectual disability services in Ireland although a national inpatient service is in the process of being set up at the Central Mental Hospital in Dublin. Vision for change (Department of Health and Children 2006) recommended that close links should be established between this team and regional forensic teams.


Forensic intellectual disability psychiatry is a relatively new field with a relatively new and limited evidence base. However, that evidence base is growing all the time. Establishing forensic intellectual disability services in Ireland is a welcome step. It is certainly in keeping with the principle of providing services closer to home. A challenge for the future is linking inpatient and regional community services. The other steps in the journey between community and inpatient services for offenders with intellectual disability also require some thought and, in particular, community packages, and identification of intellectual disability within the criminal justice system.