Introduction
It is very common to hear of the term “risk factor” in epidemiology as well as in criminal behavior studies. In general, sense, a risk factor is a term used to refer to a variable that is associated with an alleviated risk of infection, disease or disorder. The number of identified diseases, disorders and infections are very large and consequently; the number of risk factors that increase the susceptibility to them is large. Each disease, infection or disorder has its own set of risk factors. However, some risks factors that have been found apply in all three aspects mentioned above. This paper aims to explore one risk factor for a particular social disorder; criminal behavior. The risk factor to be focused is molecular genetics. As the name suggests, molecular genetics is science genre that mainly deals with functions as well as the structures of genes at a molecular level. This disciplined employs a variety of molecular biology and genetics methods to expound on the molecular interactions and functions among genes. The importance of molecular genetics in criminal behavior studies emerges when the criminal tendencies in an individual are somehow dependent on genetic make-up. To explore on this issue, this paper will conduct a literature review of two articles that focus on molecular genetics as a risk factor in criminal behavior. In addition to a comprehensive analysis of the two article’s content, the paper will supplement these articles’ contents using two support articles that also deal with the same subject. All the four articles were after an exhaustive search process at the UMUC online-library.
Article 1
Caspi, A., Langley, K., Milne, B., Moffitt, T. E., O'Donovan, M., Owen, M. J and Thapar, A. (2008). A Replicated Molecular Genetic Basis for Subtyping Antisocial Behavior in Children With Attention-Deficit/Hyperactivity Disorder. Archives of General Psychiatry, 65(2), 203-210.
Summary
This article explores one disorder that has been found to be significantly responsible for criminal tendencies in children and teenagers. The disorder in question is Attention-deficit/Hyperactivity Disorder. ADHD is a very common childhood onset neurodevelopment disorder that is usually characterized by over activity, impulsiveness and inattention. In addition, childhood ADHD extends to the adult life where it leads to various social disorders like drug abuse, failure and crime. The correlation between ADHD and antisocial behavior including criminal tendencies has been found to be partly attributable to genetic factors. Although the genes that are involved in this aspect have not been pinpointed, one particular gene that many genetic researchers have pointed fingers at is catechol O-methyltransferase gene (COMT). Scientists have suggested that this gene plays a role in influencing the expression of antisocial behavior in teenagers and children with ADHD. The researchers of this article deliver molecular genetic support for the correlation between ADHD and antisocial behavior like criminal tendencies. They do this by showing that the antisocial features associated with ADHD are related to variations in the gene encoding of the COMT enzyme. The COMT enzyme plays a very crucial role in the modulation of the PFC (prefrontal cortex) dopamine levels. This PFC dopamine is relevant when it comes to the executive cognitive dysfunctions that often characterize early and persistent antisocial behavior. The COMT gene in humans contains a valine/methionine polymorphism at the codon number 158. Polymorphism in the COMT is of varied functional relevance as homozygous Val Allele carrier have been proven to exhibit less competent PFC processing as evidenced by a worse performance when it comes to measure of executive functioning.
Thesis
The researchers of this article, therefore, wanted to show that people with ADHD who exhibit variations in the catechol O- methylate gene (COMT) in the form of being Val Allele carriers are at a greater risk of developing early onset antisocial behavior including its sequelae such as criminal behavior.
Methods, Evidence and Evaluation
The researchers used three independent samples that comprised of one ADHD cases clinical sample and two birth cohort studies. All the participants of the study were drawn from child health and psychiatry clinics in Wales and England. The birth cohort studies included one sample of 2232 British kids, born between 1994 and 1995. The second sample comprised of 1037 New Zealander kids born between 1972 and 1973. DNA was extracted from the participants either from mouthwash samples or venous blood. The participants from each sample were then split into 3 different groups on the basis of their genotype, that is; participants homozygous for the low COMT activity allele, participants homozygous for the high COMT activity allele and finally the heterozygotes. The association between antisocial behavior and the COMT gene characteristic was the measured through the use of multiple regression analysis. The possession of one Met Allele at least against the Val/Val genotype was the predictor or the independent variable. To find out if the association of the Met Val variant with antisocial behavior like criminal tendencies was stronger in officially diagnosed ADHD children than those without the disorder, an action term indicated as ADHD x COMT Val158 Met was included.
Findings
The significant finding from this study was that from the three independent samples, heterogeneity in term of antisocial behavior in children officially diagnosed with ADHD is linked to variation in the COMT gene. The Val/Val homozygotes had more indications of conduct disorder, aggressiveness and a high number of criminal offenses and arrest that the Met carriers.
Supporting Article
Thapar A, Langley K, Fowler T, Rice F, Turic D, Whittinger N, Aggleton J, Van den Bree M, Owen M, O’Donovan M. (2005). Catechol-O-Methyltransferase gene variant and birth weight predict early-onset antisocial behavior in children with attention deficit/ hyperactivity disorder. Arch Gen Psychiatry. 2005; 62(11), 1275-1278.
Summary
ADHD in children is always accompanied by a variety of antisocial behaviors in children with one of the most common being criminal tendencies. The identification of early predictors of these disorders is of crucial importance. It has been argued that prenatal environmental as well as genetic risk factors contribute significantly to this aspect, recent evidence shows that PFC function is significantly influenced by a Val/Met variant in the COMT gene. The objective of the researchers who wrote this article was to test a priori hypothesis that stated that a catechol-methyltransferase gene variant as well as birth weight are predictors of early onset antisocial behavior, especially criminal activities. The researchers of the article conducted a family based genetic study between 1997 and 2003 where children growing up with ADHD disorder were observed in the UK and underwent standardized and comprehensive assessments such as measures of antisocial and criminal behavior. It was found that early onset antisocial and criminal behavior was predicted by a COMT gene variant, specifically the homozygous Val/Val type.
Relationship between the two articles
It is quite clear that the two articles are complementary of each other. Both articles exemplify attempts by the authors to relate antisocial behavior like criminal tendencies to molecular genetic factors. The authors of both articles have gone to great lengths to conduct studies that seek to find out the relationship that exists between ADHD and antisocial behavior. In both articles, it has been found that a variation in the catechol-methyltransferase (COMT) gene, specifically the existence of a homozygous Valine/ Valine genotype is a predictor of early onset antisocial behavior like criminal tendencies. The articles are therefore in complete agreement with each other and the relationship between them is clear.
Article 2
Fergusson, D. M., Boden, J. M., & Horwood, L. J. (2012). Moderating role of the MAOA genotype in antisocial behavior. Journal of Psychiatry, 200(2), 116-123.
Summary
Thesis
There are stable Genetic x Environmental interactions between the MAOA gene variant and various environmental factors such as childhood maltreatment and maternal smoking in the course of pregnancy that are related to adult antisocial/criminal behaviors.
Method, Evidence and Evaluation
Data was gathered from the CDHS study where 1265 children had been studied form birth at regular intervals. The New Zealand Regional Health and Disability Committee approved all phases of this research. The present analysis was based on a sample comprising of 399 male cohorts members assessed for antisocial/criminal behavior in early adulthood and who were also fruitfully genotyped for the MAOA.
Between ages 28-30, the participants provided blood samples for DNA analysis. The DNA was extracted using the sodium chloride/phenol procedure. Polymerase chain reactions were then performed to determine the activity levels of the MAOA genotype. The measure of antisocial/criminal behavior outcomes was conducted in several phases from the age of 15 to 30. The participants were conclusively questioned about their self-reported property and violent offending. Investigation was also done on officially recorded violence/property convictions between the ages of 17 and 21. The personal and environmental risk factors for antisocial/criminal behavior were also measured. This factor included smoking of the mother during pregnancy, exposure to childhood maltreatment, cognitive ability (IQ of the child), family material deprivation, and lack of school qualifications. The extent of the relationship between the MAOA genotypes, the environmental/personal risk factors and antisocial/ criminal behavior was measured and analyzed using Pearson regression models.
Findings
The Pearson regression models were used to analyze three antisocial/ criminal behavior outcomes: property offending, violent offending and conviction. The results showed that individuals with low activity MAOA gene variant and who were exposed to various types of adversity in childhood such as family material derivation, maltreatment and maternal smoking in the course of pregnancy were likely more likely to engage in criminal activities in late teenagehood and early adulthood.
Supporting Article
Nilsson, K. W., Sjöberg, R. L., Damberg, M., Leppert, J., Öhrvik, J., Alm, P. O and Oreland, L. (2006). Role of Monoamine Oxidase A Genotype and Psychosocial Factors in Male Adolescent Criminal Activity. Biological Psychiatry, 59(2), 121-7.
Summary
Several psychological, biological and sociological antisocial/criminal behavior predictors have been established in research conducted in recent years. This article explores some of the recent findings that suggest that various interactions between a polymorphism in the promoter region of the MAOA gene and various psychosocial factors can actually be used to predict adolescent criminal activity. The authors conducted a research on Swedish subjects aged between 16 and 19 who were selected from various groups that represented different deviant risk behavior degrees. The study found that the carriers of a 3-repeat allele of the MAOA gene were at higher or increased risk of engaging in criminal activity when this type of gen variant interacts with pome psychosocial factors.
Relationship between the two articles
Once again, these two articles are complementary of one another. The first article shows that a gene variant of the MAOA gene interacts with various environmental and personal factors to consequently bring increased susceptibility to antisocial/criminal behavior. This finding is supported by the second article, which also shows that the MAOA gene variant interacts with various psychosocial factors to increase criminal tendencies especially in young adults. In combination, the two articles expound on the role of the MAOA gene in influencing criminal or antisocial behavior in humans.
Conclusion
In conclusion, it is fair to claim that molecular genetics is one the most common risk factors for criminal behavior. As shown in the literature review of the four articles, several genes play significant roles in the emergence and development of diseases in humans. This particular paper showed two such genes that play a role in influencing criminal behavior and these are monoamine oxidase (MAOA) and the catechol O-methyltransferase gene (COMT) genes. In spite of various genetic risk factors being established for various disorders, more research needs to be done. The humongous advancement of DNA technology will aid this research quite significantly.
References
Caspi, A., Langley, K., Milne, B., Moffitt, T. E., O'Donovan, M., Owen, M. J and Thapar, A. (2008). A Replicated Molecular Genetic Basis for Subtyping Antisocial Behavior in Children With Attention-Deficit/Hyperactivity Disorder. Archives of General Psychiatry, 65(2), 203-210.
Thapar A, Langley K, Fowler T, Rice F, Turic D, Whittinger N, Aggleton J, Van den Bree M, Owen M, O’Donovan M. (2005). Catechol-O-Methyltransferase gene variant and birth weight predict early-onset antisocial behavior in children with attention deficit/ hyperactivity disorder. Arch Gen Psychiatry. 2005; 62(11), 1275-1278.
Fergusson, D. M., Boden, J. M., & Horwood, L. J. (2012). Moderating role of the MAOA genotype in antisocial behavior. Journal of Psychiatry, 200(2), 116-123.
Nilsson, K. W., Sjöberg, R. L., Damberg, M., Leppert, J., Öhrvik, J., Alm, P. O and Oreland, L. (2006). Role of Monoamine Oxidase A Genotype and Psychosocial Factors in Male Adolescent Criminal Activity. Biological Psychiatry, 59(2), 121-7.
