Violence & the brain
Lecture 1 :
Reading 1. Fairchild et al. (2019). Conduct Disorder Primer. Nature Reviews Disease Primers
Conduct disorder (CD)
- Behaviors that violate the rights of others (physical aggression towards people or
animals, theft, property damage and rule violations)
- Emerges in childhood or adolescence
- Leading cause of referral to mental health services
- Least recognized and studied psychiatric disorders
- Associated with high societal and economic burden
- Resembles a personality disorder
- Heterogenous disorder
60% of adults with mental disorder -> had CD
Oppositional defiant disorder of CD -> ODD
Criticism of diagnostic criteria for CD:
- Based on behavioral symptoms -> uninformative about the underlying cognitive or
emotional processes that drive symptoms
Diagnostic criteria:
- Age of onset of symptoms
- Presence or absence of limited prosocial emotions (LPEs)
LPEs: symptoms such as deficits in empathy
Dimensional or categorical construct: focus on CD as a category
Overview of diagnostic approaches, review evidence regarding aetiology (the cause, set of
causes, or manner of causation of a disease or condition.) and pathophysiology of CD, and
consider effective interventions.
Epidemiology:
Prevalence
2-2.5% worldwide prevalence of CD.
10% of individuals are affected at some point during childhood and adolescence.
Twice as common in males as in females
No differences in prevalence between ethnic groups
Apparent differences account for by socio-economic status disparities
Typical age at onset of CD is during middle childhood or early adolescence
Studies typically focus on children between 5 and 18 years old
Strong evidence supports age related changes in symptoms (aggressive behaviors decline in
frequency with increasing age, non-aggressive symptoms increase across adolescence).
The prevalence of CD is relatively stable, the specific symptoms that qualify children for a
diagnosis change over time.
,Comorbidities
Co-occurrence of CD with other emotional and behavioral problems is very common
- 15 times higher risk for children with CD for ODD (temper outbursts, defiant
behaviors, irritability)
- 10 times higher risk for children with CD for ADHD (earlier age of onset, more severe
symptoms and more persistent course)
- In adolescence, CD is often associated with substance misuse.
- CD frequently occurs with major depressive disorders, especially in girls
- CD often associated with anxiety disorders
Mechanisms / Pathophysiology
Environmental risk factors
50% of variance in CD is attributable to environmental influences (prenatal, perinatal, familial
and neighborhood risk factors are thought to have a role).
Prenatal risk factors: effects of maternal stress during pregnancy on the development of the
prefrontal cortex of offspring might mediate the association of stress with CD symptoms
- Maternal smoking
- Alcohol use -> increase the risk of childhood onset conduct problems.
- Drug abuse
- Stress during pregnancy
Maternal anxiety during the last trimester of pregnancy is associated with childhood onset
conduct problems that persist from childhood into adolescence.
Perinatal risk factors:
- Obstetric complications: increased risk of early-onset serious violence. Can
compromise brain development, leading to dysfunction later in life
- Parental psychopathology
- Malnutrition: can lead to neurocognitive impairments through neuronal loss, changes
in neurotransmitter function and neurotoxicity, which might increase the risk of CD.
Frequent hunger during childhood: greater impulsivity, poorer self-control, increased
violence in adulthood.
- Exposure to heavy metals (such as lead)
Familial environment:
- Maladaptive parenting (harsh, coercive and inconsistent discipline)
- Parent-child conflict
- Especially a risk factor for CD for children at high genetic risk (first degree relatives
with antisocial behavior)
Other environmental risk factors:
- Deviant peers : reflects both social selection and social causation
- Low socio-economic status (low)
- Poverty
- Community violence (stressful life events, peer and parent-child conflict and maternal
stress)
, Heritability
Estimates between 5% and 74%
2 separate genetic factors that contribute to CD:
1. Rule breaking
2. Overt aggression
This suggests that CD is not a unified construct in terms of its genetic architecture
Higher heritability estimates in males than in females
Genetic contribution increased from childhood to adolescence
Future research:
- Dimensional approaches might be better suited than categorical approaches to
investigate the heritability of CD and its underlying mechanisms
Molecular genetics
- The genetic architecture in most individuals involves additive effects of many genetic
variants
- CD has a complex multifactorial aetiology, characterized by polygenic inheritance and
genetic heterogeneity across individuals, supplemented by the effects of
environmental factors that may interplay with genetic factors at any point during
development
Lecture 1 :
Reading 1. Fairchild et al. (2019). Conduct Disorder Primer. Nature Reviews Disease Primers
Conduct disorder (CD)
- Behaviors that violate the rights of others (physical aggression towards people or
animals, theft, property damage and rule violations)
- Emerges in childhood or adolescence
- Leading cause of referral to mental health services
- Least recognized and studied psychiatric disorders
- Associated with high societal and economic burden
- Resembles a personality disorder
- Heterogenous disorder
60% of adults with mental disorder -> had CD
Oppositional defiant disorder of CD -> ODD
Criticism of diagnostic criteria for CD:
- Based on behavioral symptoms -> uninformative about the underlying cognitive or
emotional processes that drive symptoms
Diagnostic criteria:
- Age of onset of symptoms
- Presence or absence of limited prosocial emotions (LPEs)
LPEs: symptoms such as deficits in empathy
Dimensional or categorical construct: focus on CD as a category
Overview of diagnostic approaches, review evidence regarding aetiology (the cause, set of
causes, or manner of causation of a disease or condition.) and pathophysiology of CD, and
consider effective interventions.
Epidemiology:
Prevalence
2-2.5% worldwide prevalence of CD.
10% of individuals are affected at some point during childhood and adolescence.
Twice as common in males as in females
No differences in prevalence between ethnic groups
Apparent differences account for by socio-economic status disparities
Typical age at onset of CD is during middle childhood or early adolescence
Studies typically focus on children between 5 and 18 years old
Strong evidence supports age related changes in symptoms (aggressive behaviors decline in
frequency with increasing age, non-aggressive symptoms increase across adolescence).
The prevalence of CD is relatively stable, the specific symptoms that qualify children for a
diagnosis change over time.
,Comorbidities
Co-occurrence of CD with other emotional and behavioral problems is very common
- 15 times higher risk for children with CD for ODD (temper outbursts, defiant
behaviors, irritability)
- 10 times higher risk for children with CD for ADHD (earlier age of onset, more severe
symptoms and more persistent course)
- In adolescence, CD is often associated with substance misuse.
- CD frequently occurs with major depressive disorders, especially in girls
- CD often associated with anxiety disorders
Mechanisms / Pathophysiology
Environmental risk factors
50% of variance in CD is attributable to environmental influences (prenatal, perinatal, familial
and neighborhood risk factors are thought to have a role).
Prenatal risk factors: effects of maternal stress during pregnancy on the development of the
prefrontal cortex of offspring might mediate the association of stress with CD symptoms
- Maternal smoking
- Alcohol use -> increase the risk of childhood onset conduct problems.
- Drug abuse
- Stress during pregnancy
Maternal anxiety during the last trimester of pregnancy is associated with childhood onset
conduct problems that persist from childhood into adolescence.
Perinatal risk factors:
- Obstetric complications: increased risk of early-onset serious violence. Can
compromise brain development, leading to dysfunction later in life
- Parental psychopathology
- Malnutrition: can lead to neurocognitive impairments through neuronal loss, changes
in neurotransmitter function and neurotoxicity, which might increase the risk of CD.
Frequent hunger during childhood: greater impulsivity, poorer self-control, increased
violence in adulthood.
- Exposure to heavy metals (such as lead)
Familial environment:
- Maladaptive parenting (harsh, coercive and inconsistent discipline)
- Parent-child conflict
- Especially a risk factor for CD for children at high genetic risk (first degree relatives
with antisocial behavior)
Other environmental risk factors:
- Deviant peers : reflects both social selection and social causation
- Low socio-economic status (low)
- Poverty
- Community violence (stressful life events, peer and parent-child conflict and maternal
stress)
, Heritability
Estimates between 5% and 74%
2 separate genetic factors that contribute to CD:
1. Rule breaking
2. Overt aggression
This suggests that CD is not a unified construct in terms of its genetic architecture
Higher heritability estimates in males than in females
Genetic contribution increased from childhood to adolescence
Future research:
- Dimensional approaches might be better suited than categorical approaches to
investigate the heritability of CD and its underlying mechanisms
Molecular genetics
- The genetic architecture in most individuals involves additive effects of many genetic
variants
- CD has a complex multifactorial aetiology, characterized by polygenic inheritance and
genetic heterogeneity across individuals, supplemented by the effects of
environmental factors that may interplay with genetic factors at any point during
development
