- There is good research evidence on the proportion of the UK prison population that experiences mental health problems or behavioural difficulties. The prevalence of most of these conditions is higher among the prison population compared to the general population.
- People in prison are far more likely than not to have a mental health need. There is a high degree of comorbidity, meaning most people in prison are experiencing multiple mental health needs.
- People on remand are generally at a greater risk of experiencing mental health needs than people in prison who have been sentenced. Women may experience more mental health needs than men, but men are less likely to be in contact with prison mental health services for treatment for their needs.
- Many conditions are under-recognised by services, particularly certain neurodevelopmental disorders such as attention deficit disorder and foetal alcohol spectrum disorders. There is a notable evidence gap in relation to the mental health needs in young people in prison.
Prevalence of mental health problems in the prison population
Within the UK, there have been few attempts at a national level to systematically assess the mental health needs of individuals in prison, and none recently. The Office of National Statistics published a landmark report in 1998 on the mental health needs of people in prison (Singleton, Gatward & Meltzer, 1998). Over 3,000 people were surveyed and assessed through standardised clinical interviews across all prisons in England and Wales. Through comparison to the general population, the study reported clear evidence of increased psychiatric morbidity among the prison population across a range of mental health problems, including major mental disorder, personality disorder, substance use and self-harm. In Scotland, two national needs assessments were also conducted in the 1990s (Cooke, 1994; Davidson et al., 1995), followed by a comprehensive national healthcare needs assessment in Scotland published by SPS in 2007 (Graham, 2007). Though the Graham (2007) report remains the most recent national assessment of mental health needs in Scotland's prison population, it has been noted that the policy impact of its findings are limited by the report's reliance on existing data held by SPS to estimate the prevalence of mental health needs across Scottish prisons. At a local level, several NHS Boards have undertaken or are undertaking prison mental health needs assessments to inform planning for future service provision (e.g. Flanigan, Hunter-Rowe & Smart, 2021; Kreis et al., 2016).
In the 15 years since the Graham (2007) needs assessment, a great deal has changed in the evidence base and how services are delivered in prisons. There is now a good understanding of mental health needs of the general population, and an awareness of the unique set of risk factors people in prison have for poor mental health, as well as the negative effects of imprisonment on mental health. The prison population itself has also changed, as the cohort of older people in prison has grown, so have the number of people with long-term mental health conditions. Finally, there is also a recognition that mental health needs of this population are multiple and complex, with a high degree of comorbidity, including with substance use problems.
|Condition type||Number of studies a|| Prevalence
|Substance use disorders|
|Drug use disorder||3||35 - 67|
|Alcohol use disorder||8||33 - 81|
|Schizophrenia||2||1 – 2|
|Any psychosis||5||3 – 18|
|Depressive disorder||7||19 – 55|
|Neurotic, stress-related and somatoform disorders|
|Anxiety||2||10 – 36|
|Post-traumatic stress disorder||3||8 – 16|
|Personality disorders||3||34 - 77|
|Intellectual disability||5||0 - 10|
|Attention deficit hyperactivity disorder||4||23 - 41|
|Autism spectrum disorders||4||2 - 9|
|Traumatic brain injury||4||24 - 79|
|Dementia b||2||2 - 7|
a Number of studies reporting prevalence in a UK general prison population; see Appendix A for additional study details.
b Only measured in samples aged 50+ years.
A rapid literature review gathered available evidence on the prevalence of current or recent mental health problems in the UK prison population and identified characteristics associated with increased risk of such problems. Studies were included in the review if they were conducted in a UK prison and a standardised and validated assessment tool was employed to establish the presence of a disorder or symptoms mapping onto diagnostic criteria for the disorder. A range of tools were used, including validated screening questionnaires and clinical diagnostic interviews. While many of those who screen positive for mental health problems would not meet diagnostic criteria for mental disorder, they may nevertheless benefit from support from services. In order to maximise the relevance of the review, studies where data collection took place during or after 2001 were eligible. Summary information on the prevalence of mental health problems within the UK prison population is presented in Table 1. Additional detail on study methods is available in Appendix A.
Substance use disorders
Substance use and dependence represented the most common mental health needs in the UK prison population. In fact, research shows that individuals in prison are more likely to have a substance use problem than to not have one. Due to restricted access to substances in prison, such problems are typically assessed retrospectively through screening tools, with reflection on someone's use of substances in the year prior to imprisonment. A separate needs assessment was commissioned by the Scottish Government to comprehensively evaluate needs relating to substance use in Scotland's prison population, including drugs, alcohol, and tobacco.
Alcohol is the most commonly misused substance, with the reported prevalence of alcohol use disorders (AUD) ranging between 33% (dependence only; Bebbington et al., 2017) and 81% (abuse and/or dependence; Newbury-Birch et al., 2009). Disordered use of substances other than alcohol ('drug use disorders') are reported in 35-67% of individuals in prison (Bebbington et al., 2017; Hassan et al., 2011; Tyler et al., 2019). While cannabis was identified as the most prevalent drug used in the prison population (Stewart, 2008), cocaine and heroin are the drugs most frequently associated with abuse and dependence (Jones & Hoffmann, 2006). A higher proportion of men are at risk of an AUD than women, though there is no gender difference observed for drug dependency. Substance use problems co-occur with other mental health problems in a substantial minority if not a majority of individuals in prison (Bebbington et al., 2017), though rates of so called dual-diagnosis varied considerably in this research literature depending on the number of mental health and substance use conditions assessed by any individual prevalence studies. A conservative estimate is that 18% of the prison population has both a severe mental illness and a co-occurring substance use problem (Offender Health Research Network, 2009).
The use of novel psychoactive substances (NPS), previously known as 'legal highs', is a growing threat to the safety and wellbeing of people in prison. There are four main categories to these drugs: stimulants, cannabinoid, hallucinogenic and depressant. People can and do become violent under the influence of NPS, and can experience serious adverse psychological and physical effects, including death. While there are no robust prevalence studies to date, the 2019 Scottish Prisoner Survey reported 30% of people in prison in Scotland disclosed using NPS whilst in prison, with synthetic cannabis (often known as 'Spice') being most commonly used (Scottish Prison Service, 2019a). Moreover, while prisons take measures to address this public health problem, it is recognised that the research literature has for the most part yet to catch up and therefore prevalence figures regarding problems with NPS use may not reflect the present circumstances.
Research shows between 3-18% of the UK prison population experienced psychosis in the previous month, though this reduced to 3-12% when the mode of assessment was clinical interview (Bebbington et al., 2017; Hassan et al., 2011; Jarett et al., 2012; Senior et al., 2013). These estimates include drug-induced psychosis occurring because of using drugs in prison. Psychotic disorder is more common in men, and the remand population was more likely to be acutely psychotic than the sentenced prison population. Research on the prevalence of psychotic disorder subtypes in prison is limited to schizophrenia, which is roughly equivalent to that of the general population at 1-2% (Kingston et al., 2011; Senior et al., 2013).
Available research on the prevalence of affective (mood) disorders in UK prisons is limited largely to depressive disorders, though Tyler et al (2019) found that 25% of the sample had a mood disorder, including major depression, bipolar disorder, or dysthymia. Estimates for the prevalence of depression present a wide range, an artefact of both the mode of assessment and characteristics of subgroups assessed. The detection and treatment of depression in older adults has garnered considerable research interest, as this group of individuals in prison appear to be more vulnerable to depression with increasing age. Between 19 and 32% of the UK prison population is found to be currently experiencing mild or major depression (Bebbington et al., 2017; Hassan et al., 2011; Senior et al., 2013; Tyler et al., 2019), rising to 43-55% of those over the age of 50 (Kingston et al., 2011; Murdoch et al., 2008; O'Hara et al., 2016). Women are at a greater risk of affective disorders than men. In older adults, depression is associated with poor general health as well as dementia.
Neurotic, stress-related and somatoform disorders
A third of the UK prison population is found to be experiencing clinical anxiety at any one time (Tyler et al., 2019) while as many as 10% suffer from generalised anxiety disorder (Bebbington et al., 2017). Bebbington and colleagues (2017) also reported 11% of those assessed had phobia (women were twice as likely as men) and 5.5% met criteria for panic disorder. Tyler et al (2019) reported the prevalence of somatoform disorder, or psychosomatic disorder typified by physical responses to psychological distress, to be 8% and women were at twice the risk of men. There were no studies identified which assessed the prevalence of obsessive compulsive disorder (OCD) in the general UK prison population, however a small study examining mental health needs of women in prison who were pregnant and applying for transfer to prison Mother and Baby Units found that nearly 20% of these women met criteria for OCD (Dolan et al., 2019).
PTSD is likely under-recognised and under-treated in prison, given the high proportion of individuals in prison who report exposure to traumatic events in their lifetimes as well as in the period immediately preceding incarceration. Studies have found between 8-17% of individuals in prison meet criteria for current PTSD or complex PTSD (Bebbington et al., 2017; Facer-Irwin et al., 2021; Tyler et al., 2019). PTSD is twice as common in women as men (Bebbington et al., 2017; Tyler et al., 2019). Individuals in prison who have had adverse childhood experiences, multiple traumatic events, who are survivors of sexual abuse, and those who have experienced homelessness are at greater risk of PTSD. PTSD is also highly comorbid with other mental health problems including depression, substance use disorders, and self-harm.
Just one study assessed the prevalence of eating disorders in a UK prison sample. Screening prevalence obtained by Tyler et al (2019) using the SCOFF Questionnaire identified 20% of the sample as meeting screening criteria for an eating disorder, and it was twice as common in women than as in men. While the proportion of the prison population who would meet diagnostic criteria for an eating disorder is expected to be less than 20%, research shows individuals with eating disorders have significant unmet needs.
The prevalence of having any personality disorder (PD) ranges widely from 34 to 77%; the range likely affected by differences in mode of assessment (Bebbington et al., 2017; Slade & Forrester, 2013; Tyler et al., 2019). The remand and short-term prison population is more likely to have personality disorder (Slade & Forrester, 2013). Generally, research in prison samples finds that antisocial and paranoid personality disorders are more common in men, and women are much more likely to present with borderline personality disorder. People who meet criteria for PD most often meet criteria for several subtypes. There is substantial comorbidity between PD and mental illness and substance use disorders.
There is poor recognition of neurodevelopmental disorder, including intellectual disability (ID), attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASD), and foetal alcohol spectrum disorders (FASD) in prison populations. In the UK there is variable access for assessment and diagnosis of neurodevelopmental conditions for people in the community, though fortunately in Scotland this service gap is being addressed though the development of pathways for multidisciplinary neurodevelopmental assessment and diagnosis in children and young people (Rutherford et al., 2021). It is believed that most of the UK prison population with a neurodevelopmental disorder have not received a diagnosis or treatment in relation to this. A recent screening study conducted in a sample of residents at HMP Inverness reported that 33% of the sample met screening criteria for a neurodevelopmental disorder (Young et al., 2018). Prevalence studies have found that while 0-3% of individuals in prison meet diagnostic criteria for ID (Hayes et al., 2007; Herrington, 2009), as many as 10% may have suspected or borderline ID (Hassiotis et al., 2011; McCarthy et al., 2015; Murphy et al., 2017; Young et al., 2018).
The most common neurodevelopmental disorder among the UK prison population is by far ADHD, which while prevalent in 23-41% of the prison population (Howitt & Thomson, 2015; Farooq et al., 2016; McCarthy et al., 2015; Young et al., 2018), is rarely diagnosed and treated by UK prison mental health services. ADHD significantly co-occurs with other neurodevelopmental conditions. Sixty-three percent of Scotland's prison population with suspected ASD and 40% of those with ID also met criteria for ADHD (Young et al., 2018). The prevalence of ASD ranges from 2-9% (Robinson et al., 2012; Underwood et al., 2016; Young et al., 2018). Two screening studies conducted in Scottish prison samples reporting the prevalence of ASD to be 5.5% and 9% (Robinson et al., 2012; Young et al., 2018). Reflecting on the relatively low prevalence of ASD in Scotland's prison population, Robinson et al (2012) suggested that rather than routinely screening for ASDs in prison, prison staff should be encouraged to raise concerns about individuals who may be struggling to cope in the prison environment. There were no studies assessing the prevalence of FASD within UK prisons. While the prevalence is 1-3% in UK children (McCarthy et al., 2021), FASD is thought to be overrepresented and under-recognised in criminal justice settings, as people with FASD are up to 19 times more likely to be incarcerated than those without FASD (Popova et al., 2011).
Individuals with neurodevelopmental disorder are considered more vulnerable in the prison environment, with noted issues in relation to bullying, self-advocacy, comorbid health and mental health conditions, and challenges in progression through the criminal justice system (e.g. Talbot, 2008). There is a high co-occurrence of neurodevelopmental disorder and psychiatric symptoms particularly anxiety (Young et al. 2018), an association which is even greater for individuals who meet criteria for more than one neurodevelopmental disorder.
Traumatic brain injury
People in prison commonly report a history of head injury and are more likely to report repeated head injuries, as well as moderate-to-severe head injuries, which can result in cognitive impairment and disability. Mental health service providers can offer assessment and intervention for the cognitive, psychological and behavioural difficulties resulting from traumatic brain injury (TBI). Recognising this public health problem, the Scottish Government has supported research on head injury in Scottish prisons and piloted routine screening for head injury in partnership with researchers from the University of Glasgow (Scottish Health in Custody Network, 2022).
The prevalence of TBI in UK prison research literature ranges from 24% to 79%, with variation due in large part to differences in measurement approaches. The prevalence of TBI based on self-report using validated screening tools is 60-79% of individuals in prison (McMillan et al., 2021; O'Rourke et al., 2018; Williams et al., 2010), and a data-linkage study reported that nearly one-quarter of Scotland's prison population had previously been admitted to hospital for a head injury (McMillan et al., 2019). Most individuals who reported a history of TBI report a history of repeated TBIs. TBI is slightly more common in women in prison than in men, though TBIs in men are more likely to be moderate to severe in nature. The leading causes of TBI in men is assault and road traffic accidents. In women, TBIs are most likely to be the result of domestic abuse.
The prevalence of dementia following diagnostic assessment is 2% of individuals in prison aged 50 years and older (Kingston et al., 2011) and up to 7% of those aged 50 and older screened positive for dementia on cognitive impairment assessments. Men in prison are at a greater risk of developing dementia than women (Forsyth et al., 2020). As in general population studies, dementia is a risk factor for depression in the prison population as well. Unfortunately, dementia can go unnoticed in prison settings for a considerable length of time. Forsyth et al (2020) observed that only 3% of the individuals who screened positive for dementia on cognitive assessment had a current diagnosis of dementia. The population of people in prison in Scotland is aging, with the proportion of the older adult population doubling over the last decade (The Scottish Government, 2020), underscoring the need to develop adequate methods of detecting dementia in this population and in providing appropriate mental health support to affected individuals.
Effective identification of pre-existing and current mental health needs is critical for the planning and development of prison mental health services, and support for these needs is vital to successful rehabilitation and community reintegration. This rapid review of the prevalence literature found a high burden of psychiatric and neurodevelopmental conditions in samples of people in prison in the UK. Individuals in prison are far more likely to have a current mental health need than to not. In fact, a comprehensive assessment of a range of disorders in a representative prison sample found that only 10% of individuals did not meet any criteria for a current mental disorder (Bebbington et al., 2017). Levels of comorbidity are high in this population, with studies reporting approximately half of the prison sample assessed met criteria for more than one disorder. It is concerning that these needs are often unrecognised and unmet by prison mental health services, given the large proportion of individuals in prison who have mental health needs but who are not in contact with services (Offender Health Research Network, 2009; Tyler et al., 2019).
Women in prison have a greater mental health burden compared to men, with the exception of alcohol use and psychotic disorders. Men in prison who have mental health needs are less likely than women to have had previous contact with mental health services and to be in contact with prison in-reach services, underscoring the need for more robust mental health screening procedures to detect those in need of intervention. It is concerning that neurodevelopmental disorder, particularly ADHD and FASD, is thought to be overrepresented in prison and yet detection and support for these individuals is poor. There is a notable evidence gap in our understanding of the extent and scale of mental health needs in young people under the age of 21 in prison. Finally, as the proportion of the older adult prison population increases, prison mental health services must be prepared to address the multiple psychiatric needs of this population alongside their physical health needs.
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