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Aggressive behavior model in schizophrenic patients
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Psychiatry Research 167 (2009) 58 – 65 www.elsevier.com/locate/psychres
Aggressive behavior model in schizophrenic patients Hyunjoo Song a , Sung Kil Min b,⁎ a
b
Department of Counseling and Psychotherapy, Graduate School of Professional Therapeutic Technology, Seoul Woman's University, Seoul, Republic of Korea Department of Psychiatry and Institute of Behavioral Science in Medicine, School of Medicine, Yonsei University, Seoul, Republic of Korea Received 17 November 2006; received in revised form 31 August 2007; accepted 2 January 2008
Abstract This study aimed to determine the optimal model for explaining the aggressive behavior of schizophrenic patients in relation to certain behavioral variables including anger, schizophrenic symptoms, and cognitive function. Schizophrenic patients were evaluated with the Modified Overt Aggression Scale (MOAS) for aggressive behaviors, with irritability and resentment; with the Buss-Durkee Hostility Inventory (BDHI) for anger; with the Wisconsin Card Sorting Test (WCST) and the Grooved Pegboard Test for cognitive function; and with the Positive and Negative Syndrome Scale (PANSS) for schizophrenic symptoms. The structural equation model (SEM) in AMOS 7 for the score of “aggressive behavior in the last week” in the MOAS, was used for statistical analysis. For the SEM, two factors (irritability and resentment) were selected from the BDHI and constituted the anger construct. Through factor analysis, two factors (executive function and motor function) were selected from the cognitive function measurements to constitute the cognitive function construct. Two factors (positive and negative symptoms) in the PANSS constituted the symptom construct. The best model for aggressive behavior (MOAS) with three constructs revealed a direct, significant path of “anger emotion to aggressive behavior”. This result suggests that the aggressive behavior of schizophrenic patients is directly related to anger. Schizophrenic symptoms and cognitive function were indirectly related to aggressive behavior through the relationship between the emotion of anger and aggressive behavior. © 2008 Elsevier Ireland Ltd. All rights reserved. Keywords: Aggressive behavior; Anger; Cognitive function; Schizophrenic symptom
1. Introduction Acts of aggression committed by schizophrenic patients pose a significant problem for the patients' families, friends, and community. Various factors are related to the aggressive behavior in the schizophrenic patients. In schizophrenic patients in the community, aggressive behavior has been linked to homelessness, substance intoxication, young age at onset, male gender, ⁎ Corresponding author. Tel.: +82 2 2228 1623; fax: +82 2 313 0891. E-mail address: [email protected] (S.K. Min).
medication noncompliance (Swartz et al., 1998; Martell et al., 1995), rehospitalization (Steinert et al., 1999), schizophrenic symptoms–especially positive symptoms (Cheung et al., 1997; Krakowski et al., 1999)–and cognitive dysfunction (Benton, 1968; Hoptman et al., 2002). Acts of aggression committed by schizophrenic patients in the hospital have been linked to arrival status at the hospital (voluntary vs. involuntary), female gender, substance abuse, and impaired memory functioning (Serper et al., 2005). Aggression is a complex phenomenon that operates at multiple levels; it is therefore difficult to clarify the
0165-1781/$ - see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.psychres.2008.01.003
H. Song, S.K. Min / Psychiatry Research 167 (2009) 58–65
mechanism of aggressive behavior in schizophrenic patients. First, there is controversy regarding the relationship between psychotic symptoms and aggressive behavior in schizophrenic patients. For example, according to Nolan et al.'s (2003) review, previous studies reported that schizophrenia and general psychotic symptoms were associated with a history of assaults; however, a retrospective collection of assault data impeded efforts to establish causal or even temporal connections. But Nolan et al. (2003) suggest that positive psychotic symptoms can directly influence aggressive behavior and that atypical antipsychotic medication (which appeared to have ameliorative effects on cognitive symptoms among patients with schizophrenia) might aid in the reduction of psychotic, confusionrelated assaults. However Fullam and Dolan (2006) reported the opposite finding: that emotional information processing was not related to positive or negative symptom scores, and that there was no relationship between psychotic symptoms and cognitive function. Also, there are several findings relating aggressive behavior and neurocognitive function to aggressive behavior and psychotic symptoms. Neurobiological studies have suggested that certain structural neural abnormalities are associated with violent behavior in mentally ill patients (Chesterman et al., 1994). Damasio (1995) reported that the prefrontal cortex (PFC) exerts an inhibitory influence on certain behaviors such as aggression, in addition to mediating executive function and social conduct. Neuroimaging studies of this region have reported structural abnormalities in both schizophrenia (Buchanan and Cooper, 1990) and antisocial personality disorder (Raine et al., 1997). However, Barkataki et al. (2005) have suggested that schizophrenic patients exhibit more widespread cognitive deficits regardless of the presence of aggressive behavior, although aggressive schizophrenic patients do exhibit worse executive performance than non-violent schizophrenic patients. In the normal population, two factors, emotional instability and hostility, are suggested to account for a propensity toward aggression (Caprara et al., 1996). In the review by Betterncourt et al. (2006), the relationship between personality and aggressive behavior in the nonpsychotic population had not been studied extensively enough to extrapolate this theory of aggressive behavior to schizophrenic patients. Accordingly, in order to develop effective treatment methods for aggressive symptoms in schizophrenic patients, it is important to establish how variables such as emotion, schizophrenic symptoms, and cognitive dysfunction interact with each other to cause or aggravate aggressive behavior in schizophrenic patients.
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This study was designed to determine the best model to account for the aggressive behavior of schizophrenic patients, including the emotional variables, cognitive variables, and schizophrenic symptom variables. Each variable was selected based on previous findings; for the cognitive variable, only the frontal lobe function measurements were included (Damasio, 1995; Pentelis et al., 1997). For the anger-related emotion variable, the irritability and the resentment scores in the BDHI (Betterncourt et al., 2006) were included, and for schizophrenic symptom variables, positive and negative symptom scores in the Positive and Negative Syndrome Scale (PANSS) were included. To achieve this goal, structural equation modeling (SEM) was used as the statistical method. SEM is thought to be the most effective method for investigating multiple variables simultaneously. In addition, it is more powerful than multiple regression, factor analysis, and analysis of covariance, and has the advantages of being able to use multiple dependent variables, mediating variables, and a graphical modeling interface (Ullman, 2000). This study aimed to establish a model that would explain the aggressive behavior in schizophrenic patients, specifically by determining which variable(s) had a direct and significant relationship with aggressive behavior in schizophrenic patients. 2. Methods 2.1. Subjects The study included 165 patients with schizophrenia who had been treated at the Department of Psychiatry, Yonsei University Medical Center in Korea. Patients were excluded from the study if they were younger than 18, or older than 60, had other DSM-IV (American Psychiatry Association, 1994) axis I psychiatric disorders (such as depressive disorder, bipolar disorder or drug addiction), had a history of neurological disease or simultaneous physical and neurological diseases, had an intelligence quotient lower than 70 based on the Korean Revised Wechsler Adult Intelligence Scale (WAIS-R) (Yeum et al., 1992), and/or were determined by clinicians to be unable to complete the questionnaire for other reasons. The research protocol was cleared in advance by the institutional review board (IRB) of Yonsei University Medical Center. A written informed consent for participation in this research was obtained from all subjects. Of the 165 schizophrenic patients who participated in the study, only 105 subjects who completed assessment were included in the final analysis. Among them, 80
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patients were evaluated for aggressive behavior while they were being treated as outpatients, and 25 patients were evaluated while inpatients. The study group comprised 58 male (55.2%) and 47 female (44.8%) subjects. Their age ranged from 19 to 60 years, and their mean age was 34.35 years (S.D. = 9.39). Twenty patients were married (19%), two patients had remarried (1.9%), 79 patients were not married (75.2%), and four patients were divorced or separated (3.9%). Only 20 patients had a job (23.6%). Sixty (59.4%) of them (total 101 patients except 4 missing data) had graduated from junior college or university and 41 subjects (40.6%) had graduated from high school. The diagnosis was made by psychiatrists using the Korean version of the Structured Clinical Interview for DSM-IV (SCID-I) (Han and Hong, 2000). Of the 105 patients, 39 (37.1%) had paranoid-type schizophrenia, 29 (27.6%) patients had an undifferentiated type, 28 (26.7%) had a residual type, seven (6.7%) had a schizoaffective type, one (1%) had a disorganized type, and one (1%) had a schizophreniform disorder. Age of onset ranged from 15 to 56 years, with the mean age being 25.34 years (S.D. = 7.69). Illness duration ranged from 1 to 31 years, with the mean duration being 8.63 (S.D. = 7.47). Eighty-five patients (81%) had taken antipsychotic drugs (nine patients were on no medication, and no data were available on 11). Their schizophrenic symptom condition was generally stable past the acute stage. 2.2. Assessment tasks The aggressive behavior of patients and other assessments of symptomatology and cognitive functions, were completed within 1 day. The Modified Overt Aggression Scale (MOAS) and schizophrenic symptoms were evaluated by the psychiatrists, and the cognitive function was evaluated by two clinical psychologists. The reliability coefficients for the MOAS (Cronbach α = 0.793, P b 0.001; ICC = 0.793, P b 0.001) and for the PANSS (Cronbach α = 0.793, P b 0.001; ICC = 0.793, P b 0.001) suggested a concordance in rating. 2.2.1. Modified Overt Aggression Scale (MOAS) Aggressive behavior within the last week was evaluated by psychiatrists with the Modified Overt Aggression Scale (MOAS) (Yudofsky et al., 1986). The MOAS rates the most severe act in four categories: verbal aggression, aggression against objects, aggression against self, and aggression against other people. A score from 0 to 4 is assigned to each act: 0 scores indicate increasing severity. The score in each category is
multiplied by a factor assigned to that category: 1 for verbal aggression, 2 for aggression against objects, 3 for aggression against self, and 4 for aggression against other people. Thus, the total score ranges from 0 to 40. Assessed aggressive behavior was verified again by reviewing the medical record and, in cases involving inpatients, nursing records, and also by reviewing information obtained from family members. Patients with inconsistent information were excluded from the study. Finally, 29.5% of patients reported more than one verbal aggression, 21% reported more than one aggression against objects, 7.6% reported more than one aggression against self, and 12.4% reported more than one aggression against other people. The total score ranged from 0 to 32. 2.2.2. Anger and hostility To assess subjects' anger, patients rated themselves on the Korean version of the Buss–Durkee Hostility Inventory (BDHI) (Buss and Ann, 1957), which includes subscales for assault, indirect hostility, irritability, negativism, resentment, suspicion, and verbal hostility. This is a true–false scale. In this study only two scales were used: resentment and irritability. Verbal aggression, assault, and indirect aggression were excluded because of the conceptual proximity with the dependent measurement “aggressive behavior”. Negativism and suspicion were excluded because of the conceptual proximity with another variable, “psychotic symptoms”. A total of 75 items were included, with total scores ranging from 1 to 75. Cronbach α was 0.822 (P b 0.001). 2.2.3. Schizophrenic symptoms Patients' symptoms were evaluated with the Positive and Negative Syndrome Scale (PANSS) (Kay et al., 1987). The mean score of positive symptoms was 19.44 (S.D. = 9.85), with a range from 1 to 42. The mean score of negative symptoms was 16.56 (S.D. = 8.17) with a range from 1 to 47. 2.2.4. Neuropsychological function measurements To assess the neurocognitive functions of the frontal lobe, we selected the Wisconsin Card Sorting Test (WCST) as the executive function measurement (Heaton, 1981) and the Grooved Pegboard Test as the motor function and information processing speed measurement (Matthews and Klove, 1964), based on the review by Barkataki at el., (2005). In the WCST, the number of categories completed, the total corrected raw score, and the perseverative errors raw score were used in the factor analysis. The Grooved Pegboard Test is a manipulative
H. Song, S.K. Min / Psychiatry Research 167 (2009) 58–65 Table 1 Mean and standardized deviations for each variable.
Positive symptom in PANSS Negative symptom in PANSS Irritability (BDHI) Resentment (BDHI) Grooved Pegboard Test — right RT Grooved Pegboard — left RT WCST categories completed WCST perseverative errors raw score WCST total correct raw score Aggressive behavior (total score) — MOAS
N
Mean
S.D.
94 (105)
19.44 (19.44)
9.85 (9.32)
94 (105)
16.85 (16.56)
8.17 (7.32)
84 (105) 84 (105) 96 (105)
4.55 (4.55) 3.60 (3.60) 92.10 (92.10)
2.07 (1.85) 2.08 (1.86) 31.40 (29.03)
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good, and if lower than 0.08, the model is considered appropriate. P-values b0.05 were considered significant. 3. Results
96 (105) 104.40 (104.40) 53.26 (47.00) 90 (105)
3.36 (3.36)
2.40 (2.29)
90 (105)
28.02 (28.02)
21.93 (20.29)
90 (105)
65.66 (65.66)
19.43 (17.97)
105
2.51
6.06
Parentheses indicate mean and standardized deviation after displacement of missing value using mean.
dexterity test of visual–motor coordination ability consisting of 25 holes with randomly positioned slots, in which pegs with a key along one side must be rotated to match the hole before they can be inserted. In this study, right /left reaction times (RTs) in the Grooved Pegboard Test were used in the statistical analysis. 2.3. Data analyses Descriptive data analysis and correlation and factor analysis were performed using SPSS 15.0. In factor analysis to constitute constructs from neuropsychological tests, principal axis factoring was used as the extraction method. The Oblimin with Kaiser normalization rotation method was used. A correlation test was performed among variables. The statistical method used for the model of aggressive behavior was the structural equation model (SEM) with AMOS 7.0. The scores of positive and negative symptoms in the PANSS, scores of irritability and resentment in the BDHI for anger, and two factors in the neurocognitive function tests were included as theoretical constructs in the analysis of the model. To determine the fitness of the model, the Comparative Fit Index (CFI), Tucker–Lewis Index (TLI), Normed Fit Index (NFI), and Root Mean Square Error of Approximation (RMSEA) were used. Generally, if a fit index is higher than 0.90, the model is considered appropriate. If RMSEA is lower than 0.05, the model is considered
Table 1 presents the means and standard deviations for each variable. In the factor analysis of neuropsychological measures, two factors were selected and termed, respectively, as executive function and motor function (Table 2). According to the correlation (Table 3), aggressive behavior had a direct, significant relationship with resentment and positive symptoms. Positive symptoms were significantly related to both irritability and resentment, and negative symptoms were significantly related to cognitive factors and resentment. The statistical analysis for the model of aggressive behavior of schizophrenic patients was conducted using the structural equation model with three main constructs, including an anger emotion construct (irritability and resentment), a cognitive function construct (executive function and motor function), and a schizophrenic symptom construct (positive and negative symptom scores). We tested two models. The critical difference between the models was the absence or presence of the direct path between the aggressive behavior and schizophrenic symptoms. Two kinds of models are shown in Fig. 1 (Model 1) and Fig. 2 (Model 2). Model 1, including a direct path of schizophrenic symptoms to aggressive behavior, was shown to be valid in the analysis of goodness of fit. The model demonstrated the Chi-square to be 17.31 (df = 12; P = 0.138; CFI = 0.977; TLI = 0.947; NFI = 0.934; and RMSEA = 0.065). However, this model included an insignificant path of cognitive function to symptoms (path estimate. 1.636; P = 0.147). Accordingly, this result contradicted previous research that demonstrated a significant relationship between cognitive function Table 2 Factor analysis for neuropsychological measures. Factor 1 WCST categories completed WCST total correct raw score WCST perseverative errors raw score Grooved Pegboard Test right RT Grooved Pegboard Test left RT
2
−0.911 −0.780 0.697 0.877 0.840
Extraction method: principal axis factoring. Rotation method: Oblimin with Kaiser normalization.
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H. Song, S.K. Min / Psychiatry Research 167 (2009) 58–65
Table 3 Correlations among the variables in the model (N = 105). Aggressive behavior Irritability Resentment Executive function Motor function Positive symptom Negative symptom
0.252⁎⁎ 0.181 0.078 0.107 0.252⁎⁎ 0.180
Irritability 0.502 ⁎⁎ 0.107 −0.161 0.253 ⁎⁎ 0.122
Resentment
0.270 ⁎⁎ 0.286 ⁎⁎ 0.220⁎ 0.215⁎
Executive function
0.912 ⁎⁎ 0.151 −0.208 ⁎
Motor function
Positive symptom
0.184 0.221 ⁎
0.616 ⁎⁎
⁎ Correlation is significant at the 0.05 level (2-tailed). ⁎⁎ Correlation is significant at the 0.01 level (2-tailed).
and schizophrenic symptoms. Therefore, Model 1 was not accepted as a good model. Model 2, including path of anger to aggressive behavior, was shown to be more valid than the first model, as it included a direct path of symptoms to aggressive behavior. In the analysis of goodness of fit, the model demonstrated the Chi-square to be 14.41 (df = 12; P = 0.275; CFI = 0.990; TLI = 0.976, NFI = 0.945; and RMSEA = 0.044), and included no insignificant path. The standardized regression weights for each path in the two models are described in Table 4. According to the better model (Model 2), the aggressive behavior could be explained directly by anger (the path of “anger to aggressive behavior”). Schizophrenic symptoms did not show a direct relationship to aggressive behavior, but did have a significant relationship with anger (the path of “schizophrenic symptoms to anger”). However, cognitive function did have a significant relationship with schizophrenic symptoms. In conclusion, these data analyses suggest that aggressive behavior in schizophrenic patients can be
explained by a direct relationship to anger and an indirect relationship to cognitive function and schizophrenic symptoms through anger. 4. Discussion According to the correlation, aggressive behavior had a direct, significant relationship to resentment and positive symptoms. Positive symptoms were significantly related to both irritability and resentment; negative symptoms were significantly related to cognitive factors and resentment. These data are compatible with previous studies (Nolan et al., 2003; Benton 1968; Cheung et al., 1997). However, in comparison with previous studies, this study is unique because it compared the variables simultaneously including anger within a statistical analysis to account for aggressive behavior. The results of this study demonstrated a more elaborate and integrative model of the relationship. The best model explaining the aggressive behavior in schizophrenic patients was found to include the path from anger to
Fig. 1. The aggressive behavior model in the schizophrenic patients with path of schizophrenic symptom to aggressive behavior (Model 1).
H. Song, S.K. Min / Psychiatry Research 167 (2009) 58–65
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Fig. 2. The aggressive behavior model in the schizophrenic patients with path of anger emotion to aggressive behavior (Model 2).
aggressive behavior, as well as indirect paths from schizophrenic symptoms to anger and from cognitive symptoms to schizophrenic symptoms. In other words, anger is the only variable to significantly and directly affect recent aggressive behavior in schizophrenic patients. Our results were different from those of previous reports. For example, Nolan et al. (2003) suggested that positive symptoms were directly related to aggressive behavior in the schizophrenic patient group. This difference, however, may be due to methodological differences. Nolan's study used only the frequency analysis of data from interview and video monitoring, which did not show the causal relationship among variables. The relationship of cognitive impairment with the aggressive behavior of schizophrenic patients suggested by Benton (1968) or Cheung et al. (1997)
was more elaborate in our study. In addition, cognitive function reached a significant level in the path with schizophrenic symptoms, but not aggressive behavior. Meanwhile, Barkataki et al. (2005) reported somewhat conflicting results that suggested that schizophrenic patients had broad cognitive impairment and that violent schizophrenic patients had poorer executive function than non-violent schizophrenic patients. However, this poorer executive function was not found to be directly related to aggressive behavior. Our study could provide an alternative explanation for the finding that the aggressive behavior of schizophrenic patients may be related to anger, and that cognitive impairment may affect the stimulant of anger by weakening impulse control. Also, our finding of an indirect relationship between positive symptoms and anger suggests that if anger is not stimulated, even in patients with positive
Table 4 Standardized regression weights for each path. Estimate Motor function ← Cognitive function Executive function ← Cognitive function Irritability ← Anger emotion Resentment ← Anger emotion Positive symptom ← Symptom Negative symptom ← Symptom Symptom ← Cognitive function Anger emotion ← Symptom Symptom ← Anger emotion Aggressive behavior ← Symptom Aggressive behavior ← Anger emotion
C.R.
S.E.
P
M1
M2
M1
M2
M1
M2
M1
M2
1.264 1.000 1.134 1.000 1.000 0.635 1.636
1.172 1.000 1.084 1.000 1.000 0.648 2.375 0.069
0.497
0.284
2.642
4.130
0.008
0.000
0.555
0.359
2.042
3.021
0.041
0.003
0.190 1.129
0.198 1.163 0.030
3.350 1.449
3.278 2.043 2.272
0.000 0.147
0.001 0.041 0.023
2.223 0.184
1.026 0.081 1.383
M 1 indicated Model 1 with path from symptom to aggressive behavior. M 2 indicated Model 2 with path from anger emotion to aggressive behavior.
2.167 2.266 0.570
0.030 0.023 2.427
0.015
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H. Song, S.K. Min / Psychiatry Research 167 (2009) 58–65
symptoms such as delusions or hallucinations, violent behavior would not be acted out or would not be acted out as frequently as expected. This study may have some limitations with regard to generalization. First, it is possible that using only the MOAS resulted in inaccurate measurements of aggressive behavior, although we endeavored to overcome this limitation. In future studies, multiple comprehensive evaluations should be used to analyze aggressive behavior. Second, most subjects in this study had their symptoms relatively well managed in a single hospital located in Seoul. In addition, our group did not include the relatively severely aggressive patients. Therefore, it is difficult to extrapolate our findings to a wider population. Third, this study included only executive function and motor function in neuropsychological testing and included only the evaluation of anger, excluding other emotions. Finally, the personality component, which had been implicated in the pathogenesis of aggressive behavior, was not included for analysis in our study. For a more comprehensive explanation of aggressive behavior in schizophrenic patients, further studies are needed, including studies with a more representative patient population. In addition, more diverse measurements, including other cognitive functions, other emotions, and personality factors, should be considered. However, this study is still valuable, since it clearly shows the relationships among aggressive behavior, anger, positive symptoms, and neurocognitive functions. In light of the results of this study, the approach to managing aggressive behavior should differ from that to managing schizophrenic symptoms, per se. First of all, care should be taken of patients' anger for effective prevention and management of aggressive behavior. This treatment should be different from conventional treatment, which focuses on controlling schizophrenic or psychotic symptoms. Second, the levels of anger and coping skills in schizophrenic patients, and past history of emotional experience should be carefully assessed. Third, an educational program for anger management and behavioral control in anger-provoking situations should be provided to patients. In the future, anti-anger or anti-aggression drugs should be developed based on an improved understanding of the biological basis of anger. This pharmacological approach would differ from the current approach with regard to the pharmacological mechanisms of antipsychotic drugs, or the genetics of schizophrenia. This study suggests the importance of anger as a subject for future research. Emotion is well recognized as affecting human behavior and causing medical and
psychiatric disorders. Recently, evidence has supported an association between emotional and psychiatric disorders, and between anger and various physical disorders, including cardiovascular diseases. Among emotions, anger has been the least studied in psychiatry and has been described as a “forgotten emotion” in psychiatric research (Kennedy 1992). Recently, however, anger has become a focus of research in relation to depression (Painuly et al., 2005) and to a culture-related anger syndrome reported in Korea (Min and Kim, 1998). More research is needed in the future, not only on the relationship between anger and psychiatric disorders and on the biology of anger, but also on the effective prevention and treatment of aggressive behavior and other anger-related problems. Acknowledgement The authors thank Ryewon Ko, PhD, Taekyung Kim, MS, Namhoon Lee, MS, and Jiheum Jang, MS, who conducted psychological tests, the resident psychiatrists of the Department of Psychiatry of Yonsei University Medical Center, who helped in diagnosing patients and the patient rating scales, and professor Kyungja Oh, PhD for advice and help that facilitated the ready progression of this study. This study was supported by a grant of the Biomedical Brain Research Center Grant, Ministry of Health & Welfare, Republic of Korea. (01-PJ8-PG601NE01-0003). References American Psychiatric Association, 1994. Diagnostic and Statistical Manual of Mental Disorders, 4th ed. APA, Washington, DC. Barkataki, I., Kumari, V., Das, M., Hill, M., Morris, R., O'Connell, P., Taylor, P., Sharma, T., 2005. A neuropsychological investigation into violence and mental illness. Schizophrenia Research 74 (1), 1–13. Benton, A.L., 1968. Differential behavioral effects of frontal lobe disease. Neuropsychology 6, 53–60. Betterncourt, B.A., Tally, A., Benjamin, A.J., Valentine, J., 2006. Personality and aggressive behavior under provoking and neutral condition: a meta-analytic review. Psychological Bulletin 132 (3), 751–777. Buchanan, B.J., Cooper, H.M., 1990. Effects of alcohol on human aggression: an integrative research review. Psychological Bulletin, 107, 341–354. Buss, A.H., Ann, D., 1957. An inventory for assessing different kinds of hostility. Journal of Consulting Psychology 21, 343–349. Caprara, G.V., Barbaranelli, C., Zimbardo, P., 1996. Understanding the complexity of human aggression: affective, cognitive, and social dimensions of individual differences in propensity toward aggression. European Journal of Personality 10, 133–155. Chesterman, L., Taylor, P., Cox, T., Hill, M., Lumsden, J., 1994. Multiple measures of cerebral state in dangerous mentally disordered inpatients. Criminal Behaviour and Mental Health 4, 228–238.
H. Song, S.K. Min / Psychiatry Research 167 (2009) 58–65 Cheung, P., Schweitzer, I., Crowley, K., Tuckwell, V., 1997. Aggressive behavior in schizophrenia: role of state versus trait factors. Psychiatry Research 72, 41–50. Damasio, A.R., 1995. On some functions of the human prefrontal cortex. Annals of New York Academy of Sciences 769, 241–251. Fullam, R., Dolan, M., 2006. Emotional information processing in violent patients with schizophrenia: association with psychopathy and symptomatology. Psychiatry Research 141 (1), 29–37. Han, O.S., Hong, J.P., 2000. Korean Version of Structured Clinical Interview for DSM-V. Hana Uihak Sa, Seoul. Heaton, R.K., 1981. Wisconsin Card Sorting Test Manual. Psychological Assessment Resources, Odessa, FL. Hoptman, M.J., Volavka, J., Johnson, G., Weiss, E., Bilder, R.M., Lim, K.O., 2002. Frontal white matter microstructure, aggression, and impulsivity in men with schizophrenia: a preliminary study. Biological Psychiatry 52, 9–14. Kay, S.R., Opler, L.A., Fiszbein, A., 1987. Positive and Negative Syndrome Scale (PANSS) for schizophrenia. Schizophrenia Bulletin 13 (2), 261–276. Kennedy, H.G., 1992. Anger and irritability. British Journal of Psychiatry 161, 145–153. Krakowski, M., Czobor, P., Chou, J.C., 1999. Course of violence in patients with schizophrenia: relationship to clinical symptoms. Schizophrenia Bulletin 25, 505–517. Martell, D.A., Rosner, R., Harmon, R.B., 1995. Base-rate estimates of criminal behavior by homeless mentally ill persons in New York City. Psychiatric Services 46, 596–601. Matthews, C.G., Klove, H., 1964. Instruction Manual for the Adult Neuropsychology Test Battery. University of Wisconsin Medical School, Madison, WI. Min, S.K., Kim, K.H., 1998. Symptoms of hwabyung. Journal of Korean Neuropsychiatry Association 37, 1138–1148.
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Nolan, K.A., Czobor, P., Roy, B.B., Shope, C.B., Citrome, L.L., Volavak, J., 2003. Characteristics of assaultive behavior among psychiatric inpatients. Psychiatric Services 54 (7), 1012–1016. Painuly, N., Sharan, P., Mattoo, S.K., 2005. Relationship of anger and anger attacks with depression: a brief review. European Archives of Psychiatry and Clinical Neuroscience 255, 215–222. Pentelis, C., Barnes, T.R., Nelson, H.E., Tanner, S., Weatherley, L., Owen, A.M., Robbins, T.W., 1997. Frontal–striatal cognitive deficits in patients with chronic schizophrenia. Brain 120, 1823–1843. Raine, A., Lencz, T., Bihrle, S., LaCasse, L., 1997. Brain abnormalities in murderers indicated by position emission tomography. Biological Psychiatry, 57, 119–127. Serper, M.R., Goldberg, B.R., Herman, K.G., Richarme, D., Chou, J., Dill, C.A., Cancro, R., 2005. Predictors of aggression on the psychiatric inpatient service. Comprehensive Psychiatry, 46, 121–127. Steinert, T., Wiebe, C., Gebhardt, R.P., 1999. Aggressive behavior against self and others among first-admission patients with schizophrenia. Psychiatry Services 50, 85–90. Swartz, M.S., Swanson, J.W., Hiday, V.A., Borum, R., Wagner, H.R., Burns, B.J., 1998. Aggression and severe mental illness: the effects of substance abuse and nonadherence to medication. American Journal of Psychiatry 155, 226–231. Ullman, J.B., 1996. Structural equation modeling, In: Tabachnick, B.G., Fidell, L.S. (Eds.), Using Multivariate Statistics, 3rd Ed. HarperCollins College Publishers, New York, pp. 709–819. Yeum, T.H., Park, Y.S., Oh, K.J., Kim, J.K., Lee, Y.H., 1992. K-WAIS Manual, Hankuk Guidance, Seoul. Yudofsky, S.C., Silver, J.M., Jackson, W., Endicott, J., Williams, D., 1986. Overt Aggression Scale for the objective rating of verbal and physical aggression. American Journal of Psychiatry 143, 35–39.
Psychiatry Research 167 (2009) 58 – 65 www.elsevier.com/locate/psychres
Aggressive behavior model in schizophrenic patients Hyunjoo Song a , Sung Kil Min b,⁎ a
b
Department of Counseling and Psychotherapy, Graduate School of Professional Therapeutic Technology, Seoul Woman's University, Seoul, Republic of Korea Department of Psychiatry and Institute of Behavioral Science in Medicine, School of Medicine, Yonsei University, Seoul, Republic of Korea Received 17 November 2006; received in revised form 31 August 2007; accepted 2 January 2008
Abstract This study aimed to determine the optimal model for explaining the aggressive behavior of schizophrenic patients in relation to certain behavioral variables including anger, schizophrenic symptoms, and cognitive function. Schizophrenic patients were evaluated with the Modified Overt Aggression Scale (MOAS) for aggressive behaviors, with irritability and resentment; with the Buss-Durkee Hostility Inventory (BDHI) for anger; with the Wisconsin Card Sorting Test (WCST) and the Grooved Pegboard Test for cognitive function; and with the Positive and Negative Syndrome Scale (PANSS) for schizophrenic symptoms. The structural equation model (SEM) in AMOS 7 for the score of “aggressive behavior in the last week” in the MOAS, was used for statistical analysis. For the SEM, two factors (irritability and resentment) were selected from the BDHI and constituted the anger construct. Through factor analysis, two factors (executive function and motor function) were selected from the cognitive function measurements to constitute the cognitive function construct. Two factors (positive and negative symptoms) in the PANSS constituted the symptom construct. The best model for aggressive behavior (MOAS) with three constructs revealed a direct, significant path of “anger emotion to aggressive behavior”. This result suggests that the aggressive behavior of schizophrenic patients is directly related to anger. Schizophrenic symptoms and cognitive function were indirectly related to aggressive behavior through the relationship between the emotion of anger and aggressive behavior. © 2008 Elsevier Ireland Ltd. All rights reserved. Keywords: Aggressive behavior; Anger; Cognitive function; Schizophrenic symptom
1. Introduction Acts of aggression committed by schizophrenic patients pose a significant problem for the patients' families, friends, and community. Various factors are related to the aggressive behavior in the schizophrenic patients. In schizophrenic patients in the community, aggressive behavior has been linked to homelessness, substance intoxication, young age at onset, male gender, ⁎ Corresponding author. Tel.: +82 2 2228 1623; fax: +82 2 313 0891. E-mail address: [email protected] (S.K. Min).
medication noncompliance (Swartz et al., 1998; Martell et al., 1995), rehospitalization (Steinert et al., 1999), schizophrenic symptoms–especially positive symptoms (Cheung et al., 1997; Krakowski et al., 1999)–and cognitive dysfunction (Benton, 1968; Hoptman et al., 2002). Acts of aggression committed by schizophrenic patients in the hospital have been linked to arrival status at the hospital (voluntary vs. involuntary), female gender, substance abuse, and impaired memory functioning (Serper et al., 2005). Aggression is a complex phenomenon that operates at multiple levels; it is therefore difficult to clarify the
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mechanism of aggressive behavior in schizophrenic patients. First, there is controversy regarding the relationship between psychotic symptoms and aggressive behavior in schizophrenic patients. For example, according to Nolan et al.'s (2003) review, previous studies reported that schizophrenia and general psychotic symptoms were associated with a history of assaults; however, a retrospective collection of assault data impeded efforts to establish causal or even temporal connections. But Nolan et al. (2003) suggest that positive psychotic symptoms can directly influence aggressive behavior and that atypical antipsychotic medication (which appeared to have ameliorative effects on cognitive symptoms among patients with schizophrenia) might aid in the reduction of psychotic, confusionrelated assaults. However Fullam and Dolan (2006) reported the opposite finding: that emotional information processing was not related to positive or negative symptom scores, and that there was no relationship between psychotic symptoms and cognitive function. Also, there are several findings relating aggressive behavior and neurocognitive function to aggressive behavior and psychotic symptoms. Neurobiological studies have suggested that certain structural neural abnormalities are associated with violent behavior in mentally ill patients (Chesterman et al., 1994). Damasio (1995) reported that the prefrontal cortex (PFC) exerts an inhibitory influence on certain behaviors such as aggression, in addition to mediating executive function and social conduct. Neuroimaging studies of this region have reported structural abnormalities in both schizophrenia (Buchanan and Cooper, 1990) and antisocial personality disorder (Raine et al., 1997). However, Barkataki et al. (2005) have suggested that schizophrenic patients exhibit more widespread cognitive deficits regardless of the presence of aggressive behavior, although aggressive schizophrenic patients do exhibit worse executive performance than non-violent schizophrenic patients. In the normal population, two factors, emotional instability and hostility, are suggested to account for a propensity toward aggression (Caprara et al., 1996). In the review by Betterncourt et al. (2006), the relationship between personality and aggressive behavior in the nonpsychotic population had not been studied extensively enough to extrapolate this theory of aggressive behavior to schizophrenic patients. Accordingly, in order to develop effective treatment methods for aggressive symptoms in schizophrenic patients, it is important to establish how variables such as emotion, schizophrenic symptoms, and cognitive dysfunction interact with each other to cause or aggravate aggressive behavior in schizophrenic patients.
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This study was designed to determine the best model to account for the aggressive behavior of schizophrenic patients, including the emotional variables, cognitive variables, and schizophrenic symptom variables. Each variable was selected based on previous findings; for the cognitive variable, only the frontal lobe function measurements were included (Damasio, 1995; Pentelis et al., 1997). For the anger-related emotion variable, the irritability and the resentment scores in the BDHI (Betterncourt et al., 2006) were included, and for schizophrenic symptom variables, positive and negative symptom scores in the Positive and Negative Syndrome Scale (PANSS) were included. To achieve this goal, structural equation modeling (SEM) was used as the statistical method. SEM is thought to be the most effective method for investigating multiple variables simultaneously. In addition, it is more powerful than multiple regression, factor analysis, and analysis of covariance, and has the advantages of being able to use multiple dependent variables, mediating variables, and a graphical modeling interface (Ullman, 2000). This study aimed to establish a model that would explain the aggressive behavior in schizophrenic patients, specifically by determining which variable(s) had a direct and significant relationship with aggressive behavior in schizophrenic patients. 2. Methods 2.1. Subjects The study included 165 patients with schizophrenia who had been treated at the Department of Psychiatry, Yonsei University Medical Center in Korea. Patients were excluded from the study if they were younger than 18, or older than 60, had other DSM-IV (American Psychiatry Association, 1994) axis I psychiatric disorders (such as depressive disorder, bipolar disorder or drug addiction), had a history of neurological disease or simultaneous physical and neurological diseases, had an intelligence quotient lower than 70 based on the Korean Revised Wechsler Adult Intelligence Scale (WAIS-R) (Yeum et al., 1992), and/or were determined by clinicians to be unable to complete the questionnaire for other reasons. The research protocol was cleared in advance by the institutional review board (IRB) of Yonsei University Medical Center. A written informed consent for participation in this research was obtained from all subjects. Of the 165 schizophrenic patients who participated in the study, only 105 subjects who completed assessment were included in the final analysis. Among them, 80
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patients were evaluated for aggressive behavior while they were being treated as outpatients, and 25 patients were evaluated while inpatients. The study group comprised 58 male (55.2%) and 47 female (44.8%) subjects. Their age ranged from 19 to 60 years, and their mean age was 34.35 years (S.D. = 9.39). Twenty patients were married (19%), two patients had remarried (1.9%), 79 patients were not married (75.2%), and four patients were divorced or separated (3.9%). Only 20 patients had a job (23.6%). Sixty (59.4%) of them (total 101 patients except 4 missing data) had graduated from junior college or university and 41 subjects (40.6%) had graduated from high school. The diagnosis was made by psychiatrists using the Korean version of the Structured Clinical Interview for DSM-IV (SCID-I) (Han and Hong, 2000). Of the 105 patients, 39 (37.1%) had paranoid-type schizophrenia, 29 (27.6%) patients had an undifferentiated type, 28 (26.7%) had a residual type, seven (6.7%) had a schizoaffective type, one (1%) had a disorganized type, and one (1%) had a schizophreniform disorder. Age of onset ranged from 15 to 56 years, with the mean age being 25.34 years (S.D. = 7.69). Illness duration ranged from 1 to 31 years, with the mean duration being 8.63 (S.D. = 7.47). Eighty-five patients (81%) had taken antipsychotic drugs (nine patients were on no medication, and no data were available on 11). Their schizophrenic symptom condition was generally stable past the acute stage. 2.2. Assessment tasks The aggressive behavior of patients and other assessments of symptomatology and cognitive functions, were completed within 1 day. The Modified Overt Aggression Scale (MOAS) and schizophrenic symptoms were evaluated by the psychiatrists, and the cognitive function was evaluated by two clinical psychologists. The reliability coefficients for the MOAS (Cronbach α = 0.793, P b 0.001; ICC = 0.793, P b 0.001) and for the PANSS (Cronbach α = 0.793, P b 0.001; ICC = 0.793, P b 0.001) suggested a concordance in rating. 2.2.1. Modified Overt Aggression Scale (MOAS) Aggressive behavior within the last week was evaluated by psychiatrists with the Modified Overt Aggression Scale (MOAS) (Yudofsky et al., 1986). The MOAS rates the most severe act in four categories: verbal aggression, aggression against objects, aggression against self, and aggression against other people. A score from 0 to 4 is assigned to each act: 0 scores indicate increasing severity. The score in each category is
multiplied by a factor assigned to that category: 1 for verbal aggression, 2 for aggression against objects, 3 for aggression against self, and 4 for aggression against other people. Thus, the total score ranges from 0 to 40. Assessed aggressive behavior was verified again by reviewing the medical record and, in cases involving inpatients, nursing records, and also by reviewing information obtained from family members. Patients with inconsistent information were excluded from the study. Finally, 29.5% of patients reported more than one verbal aggression, 21% reported more than one aggression against objects, 7.6% reported more than one aggression against self, and 12.4% reported more than one aggression against other people. The total score ranged from 0 to 32. 2.2.2. Anger and hostility To assess subjects' anger, patients rated themselves on the Korean version of the Buss–Durkee Hostility Inventory (BDHI) (Buss and Ann, 1957), which includes subscales for assault, indirect hostility, irritability, negativism, resentment, suspicion, and verbal hostility. This is a true–false scale. In this study only two scales were used: resentment and irritability. Verbal aggression, assault, and indirect aggression were excluded because of the conceptual proximity with the dependent measurement “aggressive behavior”. Negativism and suspicion were excluded because of the conceptual proximity with another variable, “psychotic symptoms”. A total of 75 items were included, with total scores ranging from 1 to 75. Cronbach α was 0.822 (P b 0.001). 2.2.3. Schizophrenic symptoms Patients' symptoms were evaluated with the Positive and Negative Syndrome Scale (PANSS) (Kay et al., 1987). The mean score of positive symptoms was 19.44 (S.D. = 9.85), with a range from 1 to 42. The mean score of negative symptoms was 16.56 (S.D. = 8.17) with a range from 1 to 47. 2.2.4. Neuropsychological function measurements To assess the neurocognitive functions of the frontal lobe, we selected the Wisconsin Card Sorting Test (WCST) as the executive function measurement (Heaton, 1981) and the Grooved Pegboard Test as the motor function and information processing speed measurement (Matthews and Klove, 1964), based on the review by Barkataki at el., (2005). In the WCST, the number of categories completed, the total corrected raw score, and the perseverative errors raw score were used in the factor analysis. The Grooved Pegboard Test is a manipulative
H. Song, S.K. Min / Psychiatry Research 167 (2009) 58–65 Table 1 Mean and standardized deviations for each variable.
Positive symptom in PANSS Negative symptom in PANSS Irritability (BDHI) Resentment (BDHI) Grooved Pegboard Test — right RT Grooved Pegboard — left RT WCST categories completed WCST perseverative errors raw score WCST total correct raw score Aggressive behavior (total score) — MOAS
N
Mean
S.D.
94 (105)
19.44 (19.44)
9.85 (9.32)
94 (105)
16.85 (16.56)
8.17 (7.32)
84 (105) 84 (105) 96 (105)
4.55 (4.55) 3.60 (3.60) 92.10 (92.10)
2.07 (1.85) 2.08 (1.86) 31.40 (29.03)
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good, and if lower than 0.08, the model is considered appropriate. P-values b0.05 were considered significant. 3. Results
96 (105) 104.40 (104.40) 53.26 (47.00) 90 (105)
3.36 (3.36)
2.40 (2.29)
90 (105)
28.02 (28.02)
21.93 (20.29)
90 (105)
65.66 (65.66)
19.43 (17.97)
105
2.51
6.06
Parentheses indicate mean and standardized deviation after displacement of missing value using mean.
dexterity test of visual–motor coordination ability consisting of 25 holes with randomly positioned slots, in which pegs with a key along one side must be rotated to match the hole before they can be inserted. In this study, right /left reaction times (RTs) in the Grooved Pegboard Test were used in the statistical analysis. 2.3. Data analyses Descriptive data analysis and correlation and factor analysis were performed using SPSS 15.0. In factor analysis to constitute constructs from neuropsychological tests, principal axis factoring was used as the extraction method. The Oblimin with Kaiser normalization rotation method was used. A correlation test was performed among variables. The statistical method used for the model of aggressive behavior was the structural equation model (SEM) with AMOS 7.0. The scores of positive and negative symptoms in the PANSS, scores of irritability and resentment in the BDHI for anger, and two factors in the neurocognitive function tests were included as theoretical constructs in the analysis of the model. To determine the fitness of the model, the Comparative Fit Index (CFI), Tucker–Lewis Index (TLI), Normed Fit Index (NFI), and Root Mean Square Error of Approximation (RMSEA) were used. Generally, if a fit index is higher than 0.90, the model is considered appropriate. If RMSEA is lower than 0.05, the model is considered
Table 1 presents the means and standard deviations for each variable. In the factor analysis of neuropsychological measures, two factors were selected and termed, respectively, as executive function and motor function (Table 2). According to the correlation (Table 3), aggressive behavior had a direct, significant relationship with resentment and positive symptoms. Positive symptoms were significantly related to both irritability and resentment, and negative symptoms were significantly related to cognitive factors and resentment. The statistical analysis for the model of aggressive behavior of schizophrenic patients was conducted using the structural equation model with three main constructs, including an anger emotion construct (irritability and resentment), a cognitive function construct (executive function and motor function), and a schizophrenic symptom construct (positive and negative symptom scores). We tested two models. The critical difference between the models was the absence or presence of the direct path between the aggressive behavior and schizophrenic symptoms. Two kinds of models are shown in Fig. 1 (Model 1) and Fig. 2 (Model 2). Model 1, including a direct path of schizophrenic symptoms to aggressive behavior, was shown to be valid in the analysis of goodness of fit. The model demonstrated the Chi-square to be 17.31 (df = 12; P = 0.138; CFI = 0.977; TLI = 0.947; NFI = 0.934; and RMSEA = 0.065). However, this model included an insignificant path of cognitive function to symptoms (path estimate. 1.636; P = 0.147). Accordingly, this result contradicted previous research that demonstrated a significant relationship between cognitive function Table 2 Factor analysis for neuropsychological measures. Factor 1 WCST categories completed WCST total correct raw score WCST perseverative errors raw score Grooved Pegboard Test right RT Grooved Pegboard Test left RT
2
−0.911 −0.780 0.697 0.877 0.840
Extraction method: principal axis factoring. Rotation method: Oblimin with Kaiser normalization.
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Table 3 Correlations among the variables in the model (N = 105). Aggressive behavior Irritability Resentment Executive function Motor function Positive symptom Negative symptom
0.252⁎⁎ 0.181 0.078 0.107 0.252⁎⁎ 0.180
Irritability 0.502 ⁎⁎ 0.107 −0.161 0.253 ⁎⁎ 0.122
Resentment
0.270 ⁎⁎ 0.286 ⁎⁎ 0.220⁎ 0.215⁎
Executive function
0.912 ⁎⁎ 0.151 −0.208 ⁎
Motor function
Positive symptom
0.184 0.221 ⁎
0.616 ⁎⁎
⁎ Correlation is significant at the 0.05 level (2-tailed). ⁎⁎ Correlation is significant at the 0.01 level (2-tailed).
and schizophrenic symptoms. Therefore, Model 1 was not accepted as a good model. Model 2, including path of anger to aggressive behavior, was shown to be more valid than the first model, as it included a direct path of symptoms to aggressive behavior. In the analysis of goodness of fit, the model demonstrated the Chi-square to be 14.41 (df = 12; P = 0.275; CFI = 0.990; TLI = 0.976, NFI = 0.945; and RMSEA = 0.044), and included no insignificant path. The standardized regression weights for each path in the two models are described in Table 4. According to the better model (Model 2), the aggressive behavior could be explained directly by anger (the path of “anger to aggressive behavior”). Schizophrenic symptoms did not show a direct relationship to aggressive behavior, but did have a significant relationship with anger (the path of “schizophrenic symptoms to anger”). However, cognitive function did have a significant relationship with schizophrenic symptoms. In conclusion, these data analyses suggest that aggressive behavior in schizophrenic patients can be
explained by a direct relationship to anger and an indirect relationship to cognitive function and schizophrenic symptoms through anger. 4. Discussion According to the correlation, aggressive behavior had a direct, significant relationship to resentment and positive symptoms. Positive symptoms were significantly related to both irritability and resentment; negative symptoms were significantly related to cognitive factors and resentment. These data are compatible with previous studies (Nolan et al., 2003; Benton 1968; Cheung et al., 1997). However, in comparison with previous studies, this study is unique because it compared the variables simultaneously including anger within a statistical analysis to account for aggressive behavior. The results of this study demonstrated a more elaborate and integrative model of the relationship. The best model explaining the aggressive behavior in schizophrenic patients was found to include the path from anger to
Fig. 1. The aggressive behavior model in the schizophrenic patients with path of schizophrenic symptom to aggressive behavior (Model 1).
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Fig. 2. The aggressive behavior model in the schizophrenic patients with path of anger emotion to aggressive behavior (Model 2).
aggressive behavior, as well as indirect paths from schizophrenic symptoms to anger and from cognitive symptoms to schizophrenic symptoms. In other words, anger is the only variable to significantly and directly affect recent aggressive behavior in schizophrenic patients. Our results were different from those of previous reports. For example, Nolan et al. (2003) suggested that positive symptoms were directly related to aggressive behavior in the schizophrenic patient group. This difference, however, may be due to methodological differences. Nolan's study used only the frequency analysis of data from interview and video monitoring, which did not show the causal relationship among variables. The relationship of cognitive impairment with the aggressive behavior of schizophrenic patients suggested by Benton (1968) or Cheung et al. (1997)
was more elaborate in our study. In addition, cognitive function reached a significant level in the path with schizophrenic symptoms, but not aggressive behavior. Meanwhile, Barkataki et al. (2005) reported somewhat conflicting results that suggested that schizophrenic patients had broad cognitive impairment and that violent schizophrenic patients had poorer executive function than non-violent schizophrenic patients. However, this poorer executive function was not found to be directly related to aggressive behavior. Our study could provide an alternative explanation for the finding that the aggressive behavior of schizophrenic patients may be related to anger, and that cognitive impairment may affect the stimulant of anger by weakening impulse control. Also, our finding of an indirect relationship between positive symptoms and anger suggests that if anger is not stimulated, even in patients with positive
Table 4 Standardized regression weights for each path. Estimate Motor function ← Cognitive function Executive function ← Cognitive function Irritability ← Anger emotion Resentment ← Anger emotion Positive symptom ← Symptom Negative symptom ← Symptom Symptom ← Cognitive function Anger emotion ← Symptom Symptom ← Anger emotion Aggressive behavior ← Symptom Aggressive behavior ← Anger emotion
C.R.
S.E.
P
M1
M2
M1
M2
M1
M2
M1
M2
1.264 1.000 1.134 1.000 1.000 0.635 1.636
1.172 1.000 1.084 1.000 1.000 0.648 2.375 0.069
0.497
0.284
2.642
4.130
0.008
0.000
0.555
0.359
2.042
3.021
0.041
0.003
0.190 1.129
0.198 1.163 0.030
3.350 1.449
3.278 2.043 2.272
0.000 0.147
0.001 0.041 0.023
2.223 0.184
1.026 0.081 1.383
M 1 indicated Model 1 with path from symptom to aggressive behavior. M 2 indicated Model 2 with path from anger emotion to aggressive behavior.
2.167 2.266 0.570
0.030 0.023 2.427
0.015
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symptoms such as delusions or hallucinations, violent behavior would not be acted out or would not be acted out as frequently as expected. This study may have some limitations with regard to generalization. First, it is possible that using only the MOAS resulted in inaccurate measurements of aggressive behavior, although we endeavored to overcome this limitation. In future studies, multiple comprehensive evaluations should be used to analyze aggressive behavior. Second, most subjects in this study had their symptoms relatively well managed in a single hospital located in Seoul. In addition, our group did not include the relatively severely aggressive patients. Therefore, it is difficult to extrapolate our findings to a wider population. Third, this study included only executive function and motor function in neuropsychological testing and included only the evaluation of anger, excluding other emotions. Finally, the personality component, which had been implicated in the pathogenesis of aggressive behavior, was not included for analysis in our study. For a more comprehensive explanation of aggressive behavior in schizophrenic patients, further studies are needed, including studies with a more representative patient population. In addition, more diverse measurements, including other cognitive functions, other emotions, and personality factors, should be considered. However, this study is still valuable, since it clearly shows the relationships among aggressive behavior, anger, positive symptoms, and neurocognitive functions. In light of the results of this study, the approach to managing aggressive behavior should differ from that to managing schizophrenic symptoms, per se. First of all, care should be taken of patients' anger for effective prevention and management of aggressive behavior. This treatment should be different from conventional treatment, which focuses on controlling schizophrenic or psychotic symptoms. Second, the levels of anger and coping skills in schizophrenic patients, and past history of emotional experience should be carefully assessed. Third, an educational program for anger management and behavioral control in anger-provoking situations should be provided to patients. In the future, anti-anger or anti-aggression drugs should be developed based on an improved understanding of the biological basis of anger. This pharmacological approach would differ from the current approach with regard to the pharmacological mechanisms of antipsychotic drugs, or the genetics of schizophrenia. This study suggests the importance of anger as a subject for future research. Emotion is well recognized as affecting human behavior and causing medical and
psychiatric disorders. Recently, evidence has supported an association between emotional and psychiatric disorders, and between anger and various physical disorders, including cardiovascular diseases. Among emotions, anger has been the least studied in psychiatry and has been described as a “forgotten emotion” in psychiatric research (Kennedy 1992). Recently, however, anger has become a focus of research in relation to depression (Painuly et al., 2005) and to a culture-related anger syndrome reported in Korea (Min and Kim, 1998). More research is needed in the future, not only on the relationship between anger and psychiatric disorders and on the biology of anger, but also on the effective prevention and treatment of aggressive behavior and other anger-related problems. Acknowledgement The authors thank Ryewon Ko, PhD, Taekyung Kim, MS, Namhoon Lee, MS, and Jiheum Jang, MS, who conducted psychological tests, the resident psychiatrists of the Department of Psychiatry of Yonsei University Medical Center, who helped in diagnosing patients and the patient rating scales, and professor Kyungja Oh, PhD for advice and help that facilitated the ready progression of this study. This study was supported by a grant of the Biomedical Brain Research Center Grant, Ministry of Health & Welfare, Republic of Korea. (01-PJ8-PG601NE01-0003). References American Psychiatric Association, 1994. Diagnostic and Statistical Manual of Mental Disorders, 4th ed. APA, Washington, DC. Barkataki, I., Kumari, V., Das, M., Hill, M., Morris, R., O'Connell, P., Taylor, P., Sharma, T., 2005. A neuropsychological investigation into violence and mental illness. Schizophrenia Research 74 (1), 1–13. Benton, A.L., 1968. Differential behavioral effects of frontal lobe disease. Neuropsychology 6, 53–60. Betterncourt, B.A., Tally, A., Benjamin, A.J., Valentine, J., 2006. Personality and aggressive behavior under provoking and neutral condition: a meta-analytic review. Psychological Bulletin 132 (3), 751–777. Buchanan, B.J., Cooper, H.M., 1990. Effects of alcohol on human aggression: an integrative research review. Psychological Bulletin, 107, 341–354. Buss, A.H., Ann, D., 1957. An inventory for assessing different kinds of hostility. Journal of Consulting Psychology 21, 343–349. Caprara, G.V., Barbaranelli, C., Zimbardo, P., 1996. Understanding the complexity of human aggression: affective, cognitive, and social dimensions of individual differences in propensity toward aggression. European Journal of Personality 10, 133–155. Chesterman, L., Taylor, P., Cox, T., Hill, M., Lumsden, J., 1994. Multiple measures of cerebral state in dangerous mentally disordered inpatients. Criminal Behaviour and Mental Health 4, 228–238.
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