The chapter provides an introduction to neurodevelopmental disorders and summarises recent advances in published research, focusing on the very early development and function of the human brain. The main influences on the current delivery and development of forensic healthcare services is set within the context of available policy and guidance, which is limited in part by the available research evidence to inform it. The book is divided into three sections. The first provides an overview with an introduction to individual disorders and covers aetiology, prevalence, comorbid mental disorder and relevant policy to date. The second section focuses on the clinical aspects of the range of disorders including screening, assessment, diagnosis, risk assessments and therapeutic approaches. The final section examines the pathways through the criminal justice system from police to court to disposal and addresses the specific aspect of fitness to plead or stand trial for those with neurodevelopmental disorders. This section also describes current relevant legislation within the UK as well as forensic services for those with such disorders from a national and international perspective.

The study of subthreshold neurodevelopmental disorders (STNDs) and the implications for future health, social and criminal justice services is in its infancy. Current research points towards increased vulnerability to a number of risk factors that are likely to impact both the individual and future service demand. Offenders who meet diagnostic criteria for a specific neurodevelopmental disorder are often shown to have more similarities than differences to offenders with STNDs. As well as communication and adaptive problems, similarities also include higher rates of mental disorder and increased vulnerability to suicide and self-harm. Within STNDs there exists a wide variation in presentation which may be atypical. The future study of STNDs requires a coordinated strategy and agreement as to a common definition using a dimensional approach.

This is the first book to bring together the evidence base from leading researchers and clinicians at international level on the forensic needs of people with neurodevelopmental disorders. We hope the readers will find the evidence presented in this book not only informative but a useful reference source for their day-to-day clinical practice. There are many themes running throughout the book but one key one is that people with neurodevelopmental disorders present to the forensic system as complex, with more than one health and social care need. Another theme is the challenge of how best to recognise people with neurodevelopmental disorders across the different parts of the criminal justice system, ensuring there is expertise to provide assessments early on in the journey of defendants. The availability of evidence-based treatments needs to be embedded across forensic settings including correctional settings, health facilities and community-based services.

Introduction

This chapter provides an introduction to and offers an overview of the current evidence base relating to offenders with intellectual disability. In particular, it discusses clinical presentation, risk assessment, clinical interventions and service provision for this group.

Definition and terminology

Although the term ‘mental retardation’ is still used as a diagnostic term in the International Classification of Diseases (ICD-10; World Health Organization, 1992), it is perceived to be offensive to people with intellectual disability and has been replaced in policy, administrative and legislative forums in many countries by ‘intellectual disability’ (Salvador-Carulla et al, 2011). The term mental retardation will be updated to intellectual developmental disorders in the ICD-11 manual currently being revised. Often terminology to describe this group changes according to the context. For example, intellectual disability is still often substituted for learning disabilities in the UK by both services and user groups and is the term used in the Mental Health Act. This chapter will use the term intellectual disability, which is defined as impairments in social and intellectual functioning that occur during the developmental period (Department of Health, 2001).

The Mental Health Act 1983 for England and Wales sets out the law for the assessment and treatment of people with mental disorder and the criteria for compulsory action to be taken where the person is a risk to themselves or others, while safeguarding the individual. This includes civil detention and disposal or transfer to healthcare via the courts as a sentence or pre-sentencing assessment. The Act also legislates on appropriate aftercare, treatment and consent, safeguards, advocacy and appeals. The definition of mental disorder under the Act has been updated and replaced by a wider definition in the 2007 amendments to ‘any disorder or disability of the mind’. This does not include intellectual disability per se. The Act is clear that people with intellectual disability shall not be considered ‘to be suffering from mental disorder’ and therefore cannot be considered for detention for assessment and/or treatment under the Act simply as a result of their intellectual disability, unless the disability is associated with abnormally aggressive or seriously irresponsible conduct.