The prevalence of comorbidity of antisocial personality disorder and substance misuse with other personality disorders and impact on violence and mental health outcomes
Publication Date
March 19, 2025
Creator
Abstract
Background: Personality disorders are highly prevalent in forensic populations. Several specific personality disorders are associated with violence, particularly Antisocial Personality Disorder (ASPD). The comorbidity of ASPD with other personality disorders (Other PD) is also common, and this is of particular importance when assessing and managing risk of violence in clinical settings, especially forensic settings. Considerable evidence suggests that the risk of violence is further elevated by the comorbidity of personality disorders and substance misuse (SU). The impact of these co-morbidities has been under-researched to date.
Aims and objectives: The primary purpose of this thesis is to expand understanding of the cumulative effect of meeting criteria for more than one personality disorder, specifically comorbidity with ASPD. This thesis examined what patterns or combinations of these conditions were most closely associated with violence and mental health outcomes
Methods:. In Chapter 2, a systematic review to examine the existing literature on the prevalence of comorbidity of ASPD ± Other PD ± SU, and its associations with violence and health outcomes was conducted. In Chapter 3, empirical research was conducted to investigate the prevalence of ASPD ± Other PD ± SU, and the impact of comorbidity of ASPD ± Other PD ± SU on violence and mental health outcomes, in male forensic patients aged 18-65 who were in receipt of psychiatric care in a secure hospital. Patients were categorised into four condition groups: Group 1) ASPD + Other PD + SU; Group 2) ASPD - Other PD + SU; Group 3) ASPD + Other PD - SU; Group 4) ASPD - Other PD - SU. In Chapter 4, a methodological critique to evaluate how the current personality disorder classification systems account for personality disorder comorbidities was conducted. Finally, in Chapter 5, a case study of a forensic psychiatric patient presenting with ASPD (+ high psychopathic traits), paranoid personality disorder (PPD) and SU was presented to explore the approaches to assessment, formulation and psychological intervention using schema-informed cognitive-behavioural therapy.
Results: This thesis found a high prevalence of ASPD and Cluster B personality disorder co-morbidity, particularly borderline personality disorder (BPD), in clinical and forensic populations. ASPD and BPD were associated with aggression, convictions, severe violence, reoffending, and suicidality, but the evidence on self-harming, anxiety and depression were contrary. The comorbidity of ASPD + Other PD + SU was the most prevalent in forensic patients, and was associated with severe violence and higher levels of convictions; whilst ASPD + Other PD – SU were associated with violence although less incidences of violence and fewer incidences of convictions. However, the impact on mental health outcomes appeared to be mixed and inconclusive due to limited availability of data and methodological challenges.
Conclusions: The overall findings depicted that the specific patterns of cumulative personality disorder diagnoses, being the comorbidity of ASPD + Other PD + SU, are risk factors for violence. The personality pathology appeared to be moderated by the effects of SU, which may account for manifestations of violence. Current diagnostic classification systems are over-simplistic and have failed to account for personality disorder comorbidities. This thesis highlighted the complexity of working with forensic samples with comorbidity of personality disorders and substance misuse and recommended narrowing the treatment target audience to this specific forensic sample group, being people with the comorbidity referred to above. In accordance with the risk-need-responsivity principles, the implication of doing this may mean that offender assessment and rehabilitation for this group will need to be more robust within the forensic services.
Item Type
ethesis
Thesis Type
DForenPsy
Supervisors
Subjects (LC)
Associated Schools / Departments
School of Medicine
eprints ID
78374
UoN Repository URI
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kleung Thesis June 2024 verson 2.pdf
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Examined. Forensic Psychology Doctorate Thesis
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