Conduct Disorder: Predictors, Gender and Genetics

Genetic factors contribute to risk for many childhood mental disorders.

Gender issues in childhood psychopathology are also important factors.

Boys show higher rates for conduct disorder (CD), oppositional defiant disorder (ODD) and attention deficit hyperactivity disorder (ADHD).

Nora Kerekes and colleagues in Sweden and Australia examined a large twin study of childhood behavioral and neurobehavioral disorders. The aims of this study were to better understand the developmental and genetic features with attention to gender issues.

Key features of design of this study included:

• Twin status identical (monozygotic-MZ) vs fraternal (dizygotic-DZ) was assigned via algorithm and saliva samples
• Clinical features were assessed using the Autism-Tics, AD/HD and other Comorbidities inventory
• Data analysis included descriptive statistics and twin gene-environment modelling

As expected, ODD and CD rates were higher in boy twins than in girl twins. For ODD the boy:girl prevalence rates were 3.5%:2.1%. For conduct disorder the boy:girl prevalence rates were 1.3%:0.6%.

The research team found two distinct neurodevelopmental predictors. Early concentration/attention problems led to an increase in later ODD in both boys and girls. Additionally, early social interaction problems was linked to increased CD rates in both genders.

Higher monozygotic versus dizygotic twin concordance rates indicate a significant genetic contribution. The original figure above shows the MZ v DZ rates for the boy twins abstracted from the manuscript. All three behavioral disorders as well as autism spectrum disorder (ASD) showed significant genetic contributions in the boy twins.

For girl twins a genetic contribution was identified for ODD, ADHD and ASD. Of note, CD rates were not increased in MZ girl twins compared to DZ girl twins.

The authors note their findings have clinical implications including:

• Clinicians need to be aware of the differences between boys and girls with ODD and CD
• Inattention problems are important but less evident that behavioral problems. Clinicians should be diligent in looking for attentional problems in girls as a risk for later CD
• Social interaction problems are common predictors and common comorbid features in ODD and CD
• Treatment of ODD and CD in both boys and girls should include family interventions with multimodal interventions targeting improvement in "social interaction and communication abilities".

This is an important study that emphasizes a comprehensive surveillance and assessment program for behavioral problems in both boys and girls.

Readers with more interest in this study can access the free full-text manuscript by clicking on the DOI link in the citation below.

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Kerekes, N., Lundström, S., Chang, Z., Tajnia, A., Jern, P., Lichtenstein, P., Nilsson, T., & Anckarsäter, H. (2014). Oppositional defiant- and conduct disorder-like problems: neurodevelopmental predictors and genetic background in boys and girls, in a nationwide twin study PeerJ, 2 DOI: 10.7717/peerj.359