A neuropsychological investigation into violence and mental illness

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<ul><li><p>diagnosis of APD, (ii) individuals with a history of violence and schizophrenia, (iii) individuals with schizophrenia without a</p><p>1. Introduction</p><p>Schizophrenia Research 74 (* Corresponding author. PO58, Section of Cognitive Pharma-</p><p>cology, Division of Psychological Medicine, Institute of Psychiatry,history of violent behaviour and (iv) healthy control subjects. All study groups were compared on a neuropsychological battery</p><p>designed to assess general intellectual function, executive function, attention, and processing speed. Cognitive deficits were</p><p>more widespread among individuals with schizophrenia regardless of history of violence, compared with those with APD.</p><p>Significant impairment in patients with APD was limited to processing speed. Violent individuals with schizophrenia</p><p>demonstrated poorer performance than their nonviolent schizophrenia peers on a measure of executive function. Different</p><p>cognitive impairments are manifested by individuals with APD and schizophrenia with violent behaviours, suggesting</p><p>differences in underlying pathology. Furthermore, cognitive impairment appears to be more a feature of schizophrenia than of</p><p>violent behaviour, although there is evidence that a combination of schizophrenia and violent behaviour is associated with</p><p>greater cognitive deficits.</p><p>D 2004 Elsevier B.V. All rights reserved.</p><p>Keywords: Violence; Aggression; Antisocial personality disorder; Schizophrenia; NeuropsychologyA neuropsychological investigation into violence and mental illness</p><p>Ian Barkatakia,*, Veena Kumaria,b, Mrigendra Dasc, Mary Hillc, Robin Morrisb,</p><p>Paul OConnellc, Pamela Taylorc, Tonmoy Sharmad</p><p>aDepartment of Psychological Medicine, Institute of Psychiatry, London, United KingdombDepartment of Psychology, Institute of Psychiatry, London, United Kingdom</p><p>cBroadmoor Special Hospital, Crowthorne, Berkshire, United KingdomdClinical Neuroscience Research Centre, Dartford, Kent, United Kingdom</p><p>Received 26 May 2004; received in revised form 31 July 2004; accepted 1 August 2004</p><p>Available online 11 September 2004</p><p>Abstract</p><p>Previous research has reported cognitive impairment in patients with schizophrenia and antisocial personality disorder</p><p>(APD), the two psychiatric illnesses most implicated in violent behaviour. Previous studies have focused on either group</p><p>exclusively, and have been criticized for procedural inadequacies and sample heterogeneity. The authors investigated and</p><p>compared neuropsychological profiles of individuals with APD and violent and nonviolent individuals with schizophrenia in a</p><p>single investigation. The study involved four groups of subjects: (i) individuals with a history of serious violence and a0920-9964/$ - see front matter D 2004 Elsevier B.V. All rights reserved.</p><p>doi:10.1016/j.schres.2004.08.001</p><p>De Crespigny</p><p>Kingdom. Tel.: +44 207 848 0702; fax: +44 207 848 0646.</p><p>E-mail address: I.barkataki@iop.kcl.ac.uk (I. Barkataki).2005) 113</p><p>www.elsevier.com/locate/schresPark, Demark Hill, London SE5 8AF, United</p><p>There is an undoubted significant if small associ-</p><p>ation between psychosis and violent behaviour</p></li><li><p>hrenia(Angermeyer, 2000; Tiihonen et al., 1997). The</p><p>relationship between personality disorder and violence</p><p>is much less clear, because of confounding between</p><p>measures of personality and of antisocial behaviour,</p><p>but personality disorders are heavily over-represented</p><p>in prison populations, even if antisocial personality</p><p>disorder (APD) per se is excluded (Fazel and Danesh,</p><p>2002). Furthermore, among people who have commit-</p><p>ted the most serious violence, many are co-morbid for</p><p>psychosis and/or personality disorder and the two</p><p>disorders most frequently implicated in violent behav-</p><p>iour are APD and schizophrenia (Taylor et al., 1998).</p><p>Neurobiological studies have suggested that certain</p><p>structural neural abnormalities are associated with</p><p>violent behaviour in mentally ill patients (Chesterman</p><p>et al., 1994). The two neural regions that have been</p><p>consistently cited in relation to violent behaviour in</p><p>both APD and schizophrenia in neuroimaging studies</p><p>are the prefrontal cortex and the limbic system (Das et</p><p>al., 2002). The prefrontal cortex (PFC) mediates</p><p>executive function and social conduct, in addition to</p><p>exerting an inhibitory influence on certain behaviours,</p><p>such as aggression (Damasio, 1995). Furthermore,</p><p>neuroimaging studies examining this region have</p><p>reported structural abnormalities in both schizophre-</p><p>nia (Buchanan et al., 1998) and APD samples (Raine</p><p>et al., 2000). The other implicated region is the limbic</p><p>system, an area involved in the processing of external</p><p>emotional stimuli and relaying it into emotional</p><p>response (Aggleton, 1992), and studies have demon-</p><p>strated abnormal limbic structure and function in both</p><p>schizophrenia (Chesterman et al., 1994) and APD</p><p>(Laakso et al., 2001). At the neurobiological level,</p><p>increases in violent behaviour has been linked with</p><p>reductions in serotonin (Soderstrom et al., 2001;</p><p>Volavka, 1999), reductions in dopamine (Berman</p><p>and Coccaro, 1998) as well as increases in testoster-</p><p>one (Book et al., 2001). Substance abuse is also</p><p>widely reported to exacerbate violent behaviour</p><p>(Reiss et al., 1994; Bushman and Cooper, 1990), via</p><p>its influence and interaction with neurochemical</p><p>agents such as serotonin (Virkkunen and Linnoila,</p><p>1993) and GABA (Miczek et al., 1997).</p><p>Neuropsychological studies examining cognitive</p><p>functioning in violent groups have supported neuro-</p><p>biological findings. Numerous reviews of antisocial</p><p>I. Barkataki et al. / Schizop2behaviour and neuropsychological function have</p><p>frequently cited the causal relationship between neuraldysfunction and violence (reviews: Brower and Price,</p><p>2001; Morgan and Lilienfeld, 2000; Golden et al.,</p><p>1996; Yeudall, 1977). These studies have generally</p><p>reflected the cognitive deficits that can be representa-</p><p>tive of certain types of neuropathology such as</p><p>executive function deficits reflecting PFC impairment,</p><p>but Jones (1992) proposed multiple neuropsychopa-</p><p>thological factors contributing to violent behaviour</p><p>including reduced inhibition, as well as impairment in</p><p>memory, attention and concentration.</p><p>Neuropsychological assessments of schizophrenia</p><p>populations have demonstrated deficits in a wide</p><p>range of cognitive domains including impairments in</p><p>attention, cognitive processing speed and IQ (reviews:</p><p>Sharma and Antonova, 2003; Goldberg and Gold,</p><p>1995). Schizophrenia has been linked to poor per-</p><p>formance on several aspects of executive functioning</p><p>using tests of working memory (Pantelis et al., 1997),</p><p>inhibition (Perlstein et al., 1998), and strategy</p><p>formation and planning (Morris et al., 1995). Within</p><p>the schizophrenia population, those with violent</p><p>histories are found to demonstrate impaired perform-</p><p>ance than those without a violent history on the</p><p>Wechsler Adult Intelligence Scale (WAIS) (Krakow-</p><p>ski et al., 1989) and LuriaNebraska tests (Adams et</p><p>al., 1990). One study that directly compared non-</p><p>aggressive and aggressive (co-morbid APD) schizo-</p><p>phrenia groups (Rasmussen et al., 1995) reported the</p><p>aggressive group to perform poorly than the non-</p><p>aggressive group on tasks of frontal functioning with</p><p>the reverse being true for reaction time tasks.</p><p>Unlike schizophrenia, investigations of APD and</p><p>psychopathy (a closely related condition) do not show</p><p>significant differences in general intellectual perform-</p><p>ance in comparison to healthy groups (Walsh, 1991;</p><p>Miller, 1987; Prentice and Kelly, 1963). However,</p><p>these groups still exhibit deficits in executive function</p><p>across a range of tasks especially on those indexing</p><p>response inhibition and cognitive flexibility (Dolan</p><p>and Park, 2002; Morgan and Lilienfeld, 2000;</p><p>Lapierre et al., 1995; Devonshire et al., 1988;</p><p>Gorenstein, 1982). Furthermore, performance on tests</p><p>of impulsivity and emotional response have been cited</p><p>as particularly impaired in APD (Dinn and Harris,</p><p>2000; Lapierre et al., 1995). Overall, the literature</p><p>consistently reports that APD groups display PFC-</p><p>Research 74 (2005) 113related deficits in executive function, inhibitory</p><p>control and emotional recognition. However, these</p></li><li><p>violence in patients with these mental disorders. The</p><p>principal hypotheses were: (i) relative to the healthy</p><p>hreniacontrol subjects, subjects in all clinical groups will</p><p>show impaired neuropsychological performance; (ii)</p><p>individuals with APD will demonstrate impairment on</p><p>executive function and speed of processing tasks</p><p>(related to dorsolateral prefrontal cortex function) but</p><p>will not display deficits on tasks of attention and</p><p>general intellectual functioning; (iii) the non-violent</p><p>individuals with schizophrenia will show impairment</p><p>in processing speed, attention and general intellectual</p><p>functioning, in addition to executive functioning; (iv)</p><p>individuals with schizophrenia who have also been</p><p>violent will display a greater range and magnitude of</p><p>deficits than any other groups on cognitive measures,</p><p>especially in executive functioning.</p><p>2. Methods</p><p>2.1. Subjects</p><p>Initially, 64 participants were recruited into the</p><p>study, but 6 were excluded due to withdrawal of</p><p>consent or nonparticipation. The final sample con-</p><p>sisted of incarcerated patients with a history of</p><p>violence diagnosed with APD (APD: n=14) or</p><p>schizophrenia (VS: n=13), schizophrenia patients</p><p>without violent history (NVS: n=15) and healthy</p><p>control subjects (n=15). The violent patient samples</p><p>were recruited from Broadmoor Special Hospital and</p><p>the Denis Hill unit of the Bethlem Royal Hospital.findings are controversial, as other studies have been</p><p>unable to find deficits on putatively PFC tasks</p><p>(Crowell et al., 2003; Hare, 1984) or have reported</p><p>deficits in some tasks but not others (Dinn and Harris,</p><p>2000). Published neuropsychological investigations of</p><p>APD and schizophrenia with violence have, however,</p><p>focused exclusively on either group, and there are as</p><p>yet no direct comparisons.</p><p>The current study compares neuropsychological</p><p>performance in individuals with APD and a history of</p><p>severe violence, those with schizophrenia who had</p><p>been similarly violent, non-violent individuals with</p><p>schizophrenia, and healthy control subjects, character-</p><p>izing the cognitive impairments associated with</p><p>I. Barkataki et al. / SchizopThe NVS group was recruited from South London and</p><p>Maudsley Trust Hospitals, London and control sub-jects were recruited from general public advertise-</p><p>ments in the South London Press.</p><p>Inclusion into the study required all subjects to be</p><p>male, right handed, between 18 and 45 years of age,</p><p>speak English as their first language, be free of current</p><p>substance abuse (tested by urine analysis), and have</p><p>no history of neurological conditions or head injury.</p><p>Entry to the APD group required a DSM-IV diagnosis</p><p>of antisocial personality disorder, no co-morbid</p><p>diagnosis of schizophrenia and a history of violent</p><p>behaviour that would score 4 for seriousness of</p><p>offence on the Gunn and Robertson Scale for</p><p>violence, indicative of a fatal or near fatal act of</p><p>violence against another (Gunn and Robertson, 1976).</p><p>Both VS and NVS were required to fulfill the DSM-</p><p>IV criteria for schizophrenia and could not have co-</p><p>morbid diagnosis of APD. The VS group also had to</p><p>show similar violent history as described for the APD</p><p>group while the NVS group was required to have no</p><p>significant history of violence. In addition to the</p><p>overall inclusion criteria, the control group had to</p><p>have no previous psychiatric diagnoses without any</p><p>significant history of violence.</p><p>Groups were matched according to age, ethnicity</p><p>and socio-economic background. Subjects were also</p><p>matched for number of years in education, which seems</p><p>to have resulted in comparable levels of estimated</p><p>verbal IQ as measured by the National Adult Reading</p><p>Test (Nelson and Willison, 1991). Duration of incar-</p><p>ceration was also matched for APD and VS groups.</p><p>Medication information at study entry was recorded</p><p>and neuroleptic dosage was converted into chlorpro-</p><p>mazine dosage equivalents where applicable (Table 1).</p><p>For certain tasks, the total sample number is reduced</p><p>due to equipment failure or nonparticipation and these</p><p>instances are stated in Table 2. All participants</p><p>provided written informed consent. The protocol for</p><p>this study was approved by the ethics committees of the</p><p>Institute of Psychiatry and Maudsley Hospital, London</p><p>and Broadmoor Hospital Berkshire.</p><p>2.2. Clinical ratings</p><p>Diagnoses for violent groups were based on</p><p>classification by respective treating consultants at</p><p>secure units, using the Structured Clinical Interview</p><p>Research 74 (2005) 113 3for DSM-IVAxis I disorder (SCID, First et al., 1995)</p><p>for the VS group, and the Structured Clinical Inter-</p></li><li><p>),</p><p>S.D.)</p><p>0.45)</p><p>.69)</p><p>.34)</p><p>(1.68)</p><p>e Sym</p><p>ia VS</p><p>hreniaview for DSM-IV personality disorders (SCID II, First</p><p>et al., 1997) for the APD group. Diagnoses for</p><p>schizophrenia in the NVS group were made by trained</p><p>research psychiatrists (MD, PC) using clinical inter-</p><p>Table 1</p><p>Patient demographic and clinical characteristics</p><p>Control</p><p>(N=15),</p><p>mean (S.D.)</p><p>APD</p><p>(N=14</p><p>mean (</p><p>Age 32.1 (7.47) 33.5 (1</p><p>NART score (estimated IQ) 106.9 (16.09) 96.3 (9</p><p>Violence score* 0.50 (0.85) 6.57 (1</p><p>Duration of illness (years) N/A N/A</p><p>PANSS</p><p>Positive symptoms</p><p>Negative symptoms</p><p>General psychopathology N/A N/A</p><p>Total</p><p>PCL: SV total score N/A 16.29</p><p>Dosage of neurolepticchlorpromazine</p><p>equivalents (mg/day)</p><p>N/A N/A</p><p>NART=National Adult Reading Test; PANSS=Positive and Negativ</p><p>APD=antisocial personality disorder; NVS=non-violent schizophren</p><p>Significant findings indicated by bold text.</p><p>* As measured by Gunn and Robertson Scale.</p><p>I. Barkataki et al. / Schizop4view, DSM-IV criteria and the SCID. Clinical inter-</p><p>view and the SCID nonpatient version (SCID NP,</p><p>Spitzer et al., 1995) were used in order to screen</p><p>controls to ensure they did not suffer from undiag-</p><p>nosed personality disorder or mental illness.</p><p>The Psychopathy Checklist: Screening Version</p><p>(Hart et al., 1995) was used to assess the level of</p><p>antisocial/psychopathic trait in the violent groups at</p><p>study entry, and was used to assess the degree of</p><p>psychopathy in the APD group and also to ensure that</p><p>VS subjects did not have high levels of co-morbid</p><p>psychopathic trait. While APD and psychopathy are</p><p>associated, as they are both characterized by aggres-</p><p>sive antisocial behaviour and are linked to heightened</p><p>impulsivity, they are not synonyms. While most</p><p>individuals with psychopathy will have APD, only a</p><p>small proportion of those fulfilling the APD criteria</p><p>and characterized by additional defective affective</p><p>experience will meet the criteria for psychopathy.</p><p>Subjects in the VS and NVS groups were assessed</p><p>for schizophrenia subtype and were rated for sympto-</p><p>matology using the Positive and Negative Symptom</p><p>Scale (PANSS) (Kay et al., 1987). As pure antisocialpersonality disorder is relatively rare, APD subjects</p><p>were additionally assessed for co-morbid personality</p><p>disorders.</p><p>Among the schizophrenia groups (NVS, VS)</p><p>NVS</p><p>(N=15),</p><p>mean (S.D.)</p><p>VS</p><p>(N=13),</p><p>mean (S.D.)</p><p>F df P</p><p>34.5 (7.49) 34.5 (4.94) 0.29 3,53 0.834</p><p>98.9 (13.40) 96.4 (13.93) 1.97 3,53 0.130</p><p>1.20 (1.32) 6.15 (1.46) 89.56 3,53...</p></li></ul>


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