Adult Deliberate Firesetting. Theresa A. Gannon

factors differentiating young people and adults who set fires from other justice-involved individuals or from the wider population. In the decade since their review, very little research has examined whether the developmental experiences of people who set fires are markedly different to other groups. One exception is a paper by Ducat et al. (2013a), which compared a sample of men and women with convictions for firesetting offences with case files of randomly selected convicted individuals without firesetting histories. Both groups were characterised by childhood adversity but did not appear to differ meaningfully from one another. It is worth noting that there may be within-group variability in childhood adversity for people who have set fires, evidenced by the finding that individuals who set multiple fires may be characterised by greater physical and sexual abuse in childhood (Bell et al., 2018).

      Taken together, the early lives of people who set deliberate fires in adulthood appear to be characterised by biological and experiential factors that differentiate them from the population of people who do not encounter the criminal justice system. There is also tentative evidence that genetic and neurobiological factors may differentiate people who set fires compared with those involved in other forms of criminality. There is less evidence of clear differences between the developmental experiences of people who set fires compared with other justice-involved individuals. Overall, the general picture of the developmental context of firesetting behaviour is of a literature that needs considerable updating with large robust studies.

      Mental Disorder and Psychopathology

      Firesetting behaviour has been consistently linked with mental ill health. The Multi-Trajectory Theory of Adult Firesetting (M-TTAF; Gannon et al., 2012) conceptualises mental health as a moderator of the link between causal factors and firesetting. In other words, mental ill health may exacerbate underlying risk factors to make firesetting more likely (see also McEwan & Ducat, 2016). This reflects a departure from some earlier views that presented a more direct, causal link between mental disorder and certain firesetting behaviour (e.g., Prins, 1994). Broadly speaking, the empirical research has focused on specific areas of mental disorder or psychopathology when it comes to a possible role in firesetting—pyromania, personality disorder, disorders involving psychosis, substance misuse, affective or mood disorders, and anxiety disorders.

Pyromania. Pyromania is perhaps the most obvious mental disorder to consider as linked to firesetting behaviour (and likely more causally than as a moderator). It is defined by multiple occasions of deliberate firesetting combined with tension or arousal prior to setting the fire and pleasure, gratification, or relief following setting the fire according to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; American Psychiatric Association, 2013). Furthermore, there must be evidence of interest, curiosity, or attraction towards fire. However, there is little evidence of diagnostic utility of the concept of pyromania due to the number of exclusionary criteria included in the DSM (see Ó Ciardha et al., 2017). In fact, among populations of individuals apprehended for firesetting, a diagnosis of pyromania is extremely rare (e.g., Lindberg et al., 2005; Sambrooks et al., 2021). A key reason for the rarity of pyromania diagnoses is that DSM-5 exclusion criteria stipulate that firesetting should not be better accounted for by conduct disorder, mania, or antisocial personality disorder.

      Personality disorders. The research examining personality disorders and firesetting has commonly implicated antisocial personality disorder as well as borderline personality disorder. Meta-analytic findings suggest that approximately one third of individuals apprehended for firesetting may have a personality disorder (Sambrooks et al., 2021). In summarising this literature, Nanayakkara et al. (2015; see also Tyler & Gannon, 2012) concluded that while antisocial personality disorder appears to characterise individuals who set fires (e.g., Lindberg et al., 2005; Repo et al., 1997; Vaughn et al., 2010)—and in particular those who use fire within a varied pattern of offending—borderline personality disorder and traits typically distinguish people apprehended for firesetting from other apprehended individuals (e.g., Ducat et al., 2013b; Duggan & Shine, 2001; Ó Ciardha et al., 2015a). Synthesising results across prison, secure mental health settings, and research on the wider population, personality disorder appears to be particularly characteristic of women who set fires when compared with men who have set fires and with other women (Alleyne et al., 2016; Hoertel et al., 2011; Nanayakkara et al., 2020a; Wyatt et al., 2019).

Psychosis. Psychosis and psychotic disorders (e.g., schizophrenia) have also been reported as comorbid with or otherwise linked with firesetting behaviour (Dickens & Sugarman, 2012; Nanayakkara et al., 2015; Sambrooks et al., 2021; Tyler & Gannon, 2012). Firesetting may even act as a marker for the subsequent onset of schizophrenia or schizoaffective disorder in some cases (Thomson et al., 2017). One of the most robust studies examining psychosis and a possible link with firesetting was carried out by Anwar and colleagues (2011) using a case-control design and a large sample of Swedish participants, including all individuals convicted of arson in a 13-year period. Both men and women with convictions for arson were more likely than population controls to have diagnoses of schizophrenia or other psychoses. Another well-powered study replicated the finding that there are differences between firesetting and community samples in terms of psychotic disorders, this time with a mixed-gender Australian sample (Ducat et al., 2013b). However, psychotic disorders did not differentiate individuals apprehended for firesetting from other justice-involved individuals in their sample, except when they looked specifically at schizophrenia, which was over-represented among individuals who had set fires. Using the NESARC US data, rates of self-reported diagnoses of psychotic disorders did not appear to be more prevalent among people with a history of firesetting compared with people without (Blanco et al., 2010; Vaughn et al., 2010). However, when split by gender (Hoertel et al., 2011), the same data indicated that women with a firesetting history were more likely to report psychotic disorder than women without. Psychosis and psychotic disorders also appear to be more strongly characteristic of women apprehended for arson compared with men apprehended for arson and women without firesetting histories (e.g., Anwar et al., 2011; Enayati et al., 2008).

      Substance dependence. Some of the early conclusions of an association between substance dependence and adult firesetting (see, e.g., Gannon & Pina, 2010) were based on a literature limited by small sample sizes or lack of comparison groups (Grant & Kim, 2007; Lindberg et al., 2005; Ritchie & Huff, 1999). A number of more recent robust studies appear to support these initial conclusions (Alleyne et al., 2016; Blanco et al., 2010; Ducat et al., 2013b; Hoertel et al., 2011; Ó Ciardha et al., 2015a; Sambrooks et al., 2021; Vaughn et al., 2010). Sambrooks et al. (2021) reported meta-analytic findings suggesting that two thirds of individuals with a history of firesetting in their samples had diagnoses for substance-related issues. Nationally representative US data suggested that drug and alcohol use disorders were characteristic of men and women with a lifetime history of firesetting compared with those without (Blanco et al., 2010; Hoertel et al., 2011; Vaughn et al., 2010). Comparing a large sample of individuals convicted of arson offences with offending and community individuals, Ducat et al. (2013b) found that frequency of substance misuse diagnoses were higher for people who had set fires than either of the two other groups. Breaking down the same firesetting sample by gender, Ducat et al. (2017) reported that women who had set fires were more likely than men to have a psychiatric diagnosis of substance misuse. Two related studies looking at the psychopathology of men and women with and without firesetting histories imprisoned in the UK examined the presence as well as the prominence of drug dependence in these individuals (the male participants in these studies overlapped; Alleyne et al., 2016; Ó Ciardha et al., 2015a). Male participants who had set fires showed greater presence and prominence of drug dependence than imprisoned men who had not set fires (Ó Ciardha et al., 2015a). Women who had set fires were broadly similar to men who had set fires in terms of the presence of drug dependence but appeared slightly higher in terms of the prominence of the syndrome (Alleyne et al., 2016). Imprisoned women without a history of firesetting, however, had the highest rates of drug dependence overall. Higher rates of alcohol dependence appeared to differentiate men and women who set fires from those who did not across these two studies (Alleyne et al., 2016; Ó Ciardha et al., 2015a).

Affective and anxiety disorders. Affective and/or anxiety disorders appear to