LEARNING DISABILITIES

Health Evidence Bulletins - Wales

Literature searches completed on: 31st December 1999

6: Forensic Problems and Offending

This bulletin is a supplement to, not a substitute for, professional skills and experience. Users are advised to consult the supporting evidence for a consideration of all the implications of a recommendation.

The Statements The Evidence
6a. The relationship between behavioural disturbance and forensic problems in people with intellectual disability is subtle. There is no doubt that many behaviour problems in people with severe and profound intellectual disability would be construed as offences in more able individuals.
One of the determining characteristics of an ‘offence’ is that the perpetrator is aware of behaviour that is socially sanctioned or censured. Even when someone with mild intellectual disability may understand the nature of the offence, the criminal justice response and the response of carers is diverse across cases and situationsi,ii.
General methodological difficulties with work in this area are that offenders with intellectual disability are only mentioned as part of larger offender cohorts. Where studies are specifically directed towards offenders with intellectual disability, many studies are small in subject numbersiii.
i. Clare ICH, Murphy GH. Working with offenders or alleged offenders with intellectual disabilities. In E Emerson, C Hatton, J Bromley and A Caine (eds.) Clinical Psychology and People with Intellectual Disabilities. Chichester: Wiley, 1998
(Type V evidence - expert opinion and review of some important cases)
ii. Swanson CK, Garwick GB. Treatment for low functioning sex offenders: group therapy and interagency co-ordination. Mental Retardation 1990; 28: 155-61
(Type V evidence - expert opinion based on a description of a group therapy treatment service)
iii. Johnston SJ, Halstead S. Forensic issues in intellectual disability. Current Opinion in Psychiatry 2000; (in press)
(Type V evidence - systematic review of studies over the previous year. Does not include a randomised control trial but reviews important issues and evidence relating to the current status and use of high security, medium security and community provision; issues of consent, capacity, competence, assessment and treatment effectiveness)
6b. An important practical problem encountered when considering the population of individuals who offend is one of identifying those people with a intellectual disability and ensuring they are offered the additional safeguard of having an Appropriate Adult present during police interviewsi. i. Robertson G. The Role of Surgeons. Research Study No 6. Royal Commission on Criminal Justice. London: HMSO, 1992
(Type V evidence - expert opinion)

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6c. It is generally considered that the prevalence rates for offenders with intellectual disability may be higher than those in the general population. This is especially true for sexual offences and arsoni,ii,iii,iv,v. i. Walker N, McCabe S. Crime and Insanity in England. Edinburgh: University Press, 1973
(Type III and V evidence - review of legislation, secure hospital provision and prison services up until 1973. Detailed review of statistics from 1950-1970 relating to criminals with a psychiatric diagnosis)
ii. Murphy WD, Coleman EM, Haynes MR. Treatment and evaluation issues with the mentally retarded sex offender. In Greer JG, Stuart IR (eds.). The Sexual Aggressor: Current Prospectives on Treatment. New York: Van Nostrand, Reinhold, 1983. pp. 22-41
(Type IV evidence - review of treatment work with men who have committed sex offences. Treatments included plethysmographic assessment and electrical aversion; number of participants not noted)
iii. Hayes S. Sex offenders. Australia and New Zealand Journal of Developmental Disabilities 1991; 17: 221-7
(Type V evidence - expert opinion based on an extensive review of clinical cases. 12-13% of offenders in the New South Wales prison population were assessed as having intellectual disability)
iv. Raesaenen P, Hirvenoja R, Hakko H, Vaeisaenen E. Cognitive functioning ability of arsonists. Journal of Forensic Psychiatry 1994; 5: 615-20
(Type III evidence - a study of 72 arsonists examined before trial they found that 11% fell into the range of intellectual disability)
v. Bradford J, Dimock J. A comparative study of adolescents and adults who wilfully set fires. Psychiatric Journal of the University of Ottawa 1986; 11: 228-34
(Type III evidence - out of 57 adults and 47 juvenile arsonists they found intellectual disability to be the diagnosis in just over 10% of both groups)

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6d. Well controlled studies have found prevalence rates for individuals with intellectual disability to be slightly higher in offender populations than in the general population. There is a vast predominance of males amongst offenders with intellectual disabilityi,ii. i. MacEachron AE. Mentally retarded offenders: prevalence and characteristics. American Journal of Mental Deficiency (American Journal on Mental Retardation) 1979; 84: 165-76
(Type III evidence - review of 3938 adult male offenders. Offending rates were only slightly higher than in the general population)
ii. Borthwick-Duffy SA. Epidemiology and prevalence of psychopathology in people with mental retardation. Journal of Consulting and Clinical Psychology 1994; 62(1): 17-27
(Type IV evidence - review of 8 observational studies between 1975 & 1985 involving adults with intellectual disability in both the hospital and community settings)
6e. The way in which intelligence is measured and the use of different population bases leads to a wide variability in prevalence statistics across studiesi.
For these reasons there is little substantive evidence to support any link between the presence of intellectual impairment and a predisposition to criminal behaviour. Different studies report prevalence rates for intellectual disability within prison populations varying from around 2% to around 40%.
i. Holland AJ. Challenging and offending behaviour by adults with developmental disorders. Australia and New Zealand Journal of Developmental Disabilities 1991; 17: 119-26
(Type V evidence - expert opinion based on a review of a range of relevant studies)

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6f. In-patient treatment has been provided for individuals who have shown offending behaviours of violence, fire-setting, sexual abuse and also for individuals who have offended and have concurrent intellectual disability and psychiatric illness. Reports on the short-term outcome for individual case studies have been encouragingi,ii,iii.
(Health gain notation – 2 "likely to be beneficial")
i. Murphy GH, Holland AJ, Fowler P, Reep J. MIETS: A service option for people with mild mental handicaps and challenging behaviour or psychiatric problems 1. Philosophy service and service users. Mental Handicap Research (Journal of Applied Research in Intellectual Disabilities) 1991; 4: 41-66
(Type IV evidence - review of a series of cases)
ii. Murphy GH, Clare ICH. MIETS: A service option for people with mild mental handicaps and challenging behaviour or psychiatric problems. Assessment, treatment and outcome for service users and service effectiveness. Mental Handicap Research 1991; 4: 180-206
(Type IV evidence - review of a series of cases)
iii. Day K. Male mentally handicapped sex offenders. British Journal of Psychiatry 1994; 165: 630-39
(Type III evidence - review of 47 male sex offenders admitted to hospital. Detailed review of characteristics and recommendations for treatment provision)
6g. Study of longer term outcomes indicates that 84.2% of treated patients return to community based resources. Arsonists are over-represented in those with a poorer outcomei. i. Xenitidis KI, Henry J, Russell AJ, et al. An in-patient treatment model for adults with mild intellectual disability and challenging behaviour. Journal of Intellectual Disability Research 1999; 43: 128-34
(Type III evidence - systematic review of cases from 1987-1998 which found that 54.7% of admissions were offenders)
6h. Reviews of high security provision indicate that offenders with intellectual disability have the longest duration of stay and are the most difficult to discharge because of the lack of availability of suitable discharge resourcesi,ii. i. Jamieson E, Butwell M, Taylor P, et al. Trends in special (high security) hospitals, 1: referrals and admissions. British Journal of Psychiatry 2000; 176: 253-9
(Type III evidence - review of referrals and admissions to 3 high security hospitals)
ii. Butwell M, Jamieson E, Leese M, et al. Trends in special (high security) hospitals, 2: residency and discharge episodes. British Journal of Psychiatry 2000; 176: 260-5
(Type III evidence - systematic review and analysis of the case registers of 3 high security hospitals over a 10 year period from 1986-95)

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6i. More recently, clinicians and researchers have begun to address the problem of treatment in the community for individuals who have offended. Without necessarily admitting clients for in-patient treatment, several reports have suggested the feasibility of such treatmenti,ii,iii,iv,v.
(Health gain notation – 2 "likely to be beneficial")
i. Lindsay WR, Neilson C, Smith AHW, et al. The treatment of six men with a learning disability convicted of sex offences with children. British Journal of Clinical Psychology 1998; 37: 83-98
(Type IV evidence - detailed process study of 6 cases. No re-offending is reported 4 years following the initial conviction although the authors did not feel confident about re-offending data in one case)
ii. Lindsay WR, Olley S, Baillie N, Smith AHW. Treatment of adolescent sex offenders with intellectual disability. Mental Retardation 1999; 37: 201-11
(Type IV evidence - review of four case studies: no re-offending reported 3 years following initial conviction)
iii. Lindsay WR, Marshall I, Neilson CQ, Quinn K, Smith AHW. The treatment of men with learning disability convicted of exhibitionism. Research in Developmental Disabilities 1998; 19: 295-316
(Type IV evidence – a detailed process study of four cases. No reoffending reported four years following initial conviction)
iv. Clare ICH, Murphy GH, Cox D, Chaplin EH. Assessment and treatment of fire-setting: a single case investigation using a cognitive behavioural model. Criminal Behaviour and Mental Health 1992; 2: 253-68
(Type IV evidence - case study review of a series of cases)
v. O’Connor W. A problem solving intervention for sex offenders with an intellectual disability. Journal of Intellectual and Developmental Disability 1996; 21: 219-35
(Type IV evidence - description of a problem solving intervention with 13 adult male sex offenders aged 17-43 years. Most subjects achieved more community access)

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6j. Characteristics and predisposing factors. Sex offenders with intellectual disability may have a high incidence of family psychopathology, low specificity for age and sex of the victim, psycho-social deprivation, behavioural disturbances at school, psychiatric illness, social naivety, poor ability to form normal sexual and personal relationships, poor impulse control and low self-esteemi,ii,iii.
Experience of sexual and physical abuse in childhood is associated with offending in adulthood although it is neither a necessary or sufficient cause of adult offending including sexual offendingiv,v,vi.
Sex offenders with learning disability have a greater tendency to offend against male children and younger childrenvii.
i. Day K. Male mentally handicapped sex offenders. British Journal of Psychiatry 1994; 165: 630-9
(Type III evidence - review of 47 male patients referred for antisocial sexual behaviour)
ii. Caparulo F. Identifying the developmentally disabled sex offenders. Sexuality and Disability 1991; 9: 311-322
(Type V evidence - expert opinion based on clinical evidence and experience)
iii. Winter N, Holland AJ, Collins S. Factors predisposing to suspected offending by adults with self-reported learning disabilities. Psychological Medicine 1997; 27: 595-607
(Type IV evidence - investigation into adults charged with offences and/or leaving custody. Only two subjects with a self-reported intellectual disability actually had an IQ below 70)
iv. Langevin R, Pope S. Working with learning disabled sex offenders. Annals of Sex Research 1993; 6: 149-160
(Type V evidence – expert opinion based on clinical evidence)
v. Thompson D. Profiling the sexually abusive behaviour of men with intellectual disabilities. Journal of Applied Research and Intellectual Disabilities 1997; 10: 125-139
(Type IV evidence – an analysis of the characteristics of 75 men who had allegedly perpetrated some form of sexual abuse)
vi. Lindsay WR, Law J, Smith AHW, et al. A comparison of physical and sexual abuse histories of sexual and non-sexual offenders with intellectual disability. Child Abuse and Neglect 2000; (In Press)
(Type IV evidence – study comparing the abuse histories of 46 sexual offenders with 48 non-sexual offenders)
vii. Blanchard R, Watson M, Choy A et al. Pedophiles: Mental retardation, maternal age and sexual orientation. The Archives of Sexual Behavior 1999; 28(2): 111-127
(Type IV evidence – study, by interview, clinical chart information, phallometric tests and self-administered questionnaire, of 991 male sexual offenders)

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6k. Studies have found re-offending rates of untreated offenders of between 40 and 70%i,ii.
The risk of recidivism is highest during the year immediately following dischargeiii.
A range of studies have found re-offending rates following treatment to be between 20 and 55% depending on the type of treatment and the offenceiv.
Outcomes for individuals treated for 2 or more years would appear to be superior to outcomes for individuals treated for less than one yearv,iv.

(Health gain notation – 2 "likely to be beneficial")

i. Scorzelli JF, Reinke-Scorzelli M. Mentally retarded offender: a follow-up study. Rehabilitation Counselling Bulletin 1979; September: 70-73
(Type III evidence - review of 135 offenders with intellectual disability found that 68% had a prior history of arrest)
ii. Klimecki MR, Jenkinson J, Wilson L. A study of recidivism amongst offenders with an intellectual disability. Australia and New Zealand Journal of Developmental Disabilities 1994; 19: 209-19
(Type III evidence - detailed review of 75 incarcerated offenders with intellectual disability. Recidivism rates were 41.3% with 84% of recidivism occurring within 12 months of release from prison)
iii. Day K. Crime and mental retardation: a review. In Howells K, Hollin CR (eds.) Clinical Approaches to the Mentally Disordered Offender. Cambridge: John Wyllie, 1993
(Type IV evidence – expert opinion based on clinical experience and a review of the literature)
iv. Thomas DH, Singh T. Offenders referred to a learning disability service: a retrospective study from one county. British Journal of Learning Disabilities 1995; 23: 24-7
(Type IV evidence - 3 year follow-up of 20 offenders treated in a community based service: 50% of subjects re-offended and appeared before a court)
v. Brier N. Targeted treatment for adjudicated youths with learning disabilities: effects on recidivism. Journal of Learning Disabilities 1994; 27: 215-22
(Type III evidence - controlled group study comparing 73 offenders who completed the treatment requirements with 85 who did not and a further matched group of 34 untreated subjects. Over an average follow-up period of 20 months, the completors had a significantly lower recidivism rate (12%) relative to the non-completors (40%) and the matched controls (38%))
vi. Lindsay WR, Smith AHW. Responses to treatment for sex offenders with a learning disability: a comparison of men with one year and two year probation sentences. Journal of Intellectual Disabilities Research 1998; 42: 346-53
(Type III evidence - comparison of two groups of sex offenders. significant differences were found between the groups with the greater and most durable changes occuring in the group treated for a longer duration)

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6l. Representation, consent and competence. People with an intellectual disability may be disadvantaged by the judicial process because of lack of appropriate support and appropriate legal representation from early stages in the processi,ii,iii,iv,v. i. Cockram J, Jackson R, Underwood R. People with an intellectual disability in the criminal justice system: the family perspective. Journal of Intellectual and Developmental Disability 1998; 23: 41-55
(Type IV evidence - review of cases and analysis of the responses of 20 carers involved with offenders with intellectual disability)
ii. Hayes SC. Prevalence of intellectual disability and local courts. Journal of Intellectual and Developmental Disability 1997; 22: 71-85
(Type IV evidence - review of 208 individuals appearing before 6 courts. The review emphasises the need for policies safeguarding the rights of people with intellectual disability in the criminal justice system)
iii. Gudjonsson G, MacKeith J. Learning disability and the Police and Criminal Evidence Act 1984. Protection during investigative interviewing: a video recorded false confession to double murder. Journal of Forensic Psychiatry 1994; 5: 35-49
(Type IV evidence - careful case study illustrating the psychological processes causing an individual to confess falsely to a double murder)
iv. Kebbell MR, Hatton C. People with mental retardation as witnesses in court: a review. Mental Retardation 1999; 37: 179-87
(Type I evidence - comprehensive review which concludes that in general people with intellectual disability can provide accurate accounts of evidence. Cross-examination methods may lead to memory distortions. Resulting errors could lead to false conviction or acquittal)
v. Everington C, Fulero SM. Competence to confess: measuring understanding and suggestibility of defendants with mental retardation. Mental Retardation 1999; 37: 212-20
(Type III evidence - group comparison of individuals with and without intellectual disability. Participants with intellectual disability were significantly less able to comprehend their Miranda rights. They were also more likely to respond to suggestive questioning)

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Health Evidence Bulletins: Wales, Duthie Library, UWCM, Cardiff CF14 4XN. e-mail: weightmanal@cardiff.ac.uk