What do we know about Behavioural Disorders

By A/P Yeo Lay See
Psychology and Child & Human Development Academic Group, NIE, NTU
Published: 1 August 2022


Overview of Behavioural Disorders

Behavioural disorders fall into a category called ‘Disruptive, Impulse-Control and Conduct Disorders’ in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) (American Psychiatric Association, 2013). A key characteristic is difficulty in controlling one’s emotions and behaviours. Under normal circumstances, over a long period of time, having a behaviour disorder can adversely affect a student’s day-to-day functioning, such as academic performance, social adjustment and interpersonal relationships. Because these behaviours are visible and draw negative attention, they are aptly termed ‘externalising behaviours.’

The common behavioural disorders include oppositional defiant disorder (ODD), intermittent explosive (IED) disorder, conduct disorder (CD), and anti-social personality disorder (ASPD). Attention deficit hyperactivity disorder (ADHD) is no longer classified as a disruptive behavioural disorder but a neurodevelopmental disorder. Nonetheless, Individuals with ADHD may also exhibit impulsive, aggressive behaviours.

The above-mentioned behavioural disorders each have their own diagnostic criteria. Details can be found in the DSM-5 (American Psychiatric Association, 2013). However, they share key characteristics. In all, the behavioural challenges occur frequently and exceed what is normal for the individual’s age, gender and culture. Obvious behavioural difficulties that cut across ODD, CD, IED, ASPD are poor self-control, irritability, impulsivity, temper tantrums, arguments, fights, and physical aggression. Students with behaviour disorders are hostile and uncooperative, thus they often experience conflict with teachers and authority figures. Those with CD are apt to attract the attention of the law as their behaviours (e.g., theft, assault, cruelty to animals, vandalism) infringe on the basic rights of others and violate societal norms. Salient to individuals who develop ASPD is a blatant disregard for others’ safety and a lack of remorse for wrongdoing.

Below is a brief description of each behavioural disorder.

Oppositional Defiant Disorder (ODD)

ODD is characterized by a frequent and persistent pattern of angry/irritable mood, argumentative/defiant behaviour or vindictiveness lasting at least six months. Children and adolescents with ODD are hostile and uncooperative. They have temper tantrums and get into arguments with authority figures. These behaviours occur so frequently they exceed what is normal for the individual’s age, gender and culture. (American Psychiatric Association, 2013). It is concerning as ODD is a common precursor to the childhood-onset type of CD.

Intermittent Explosive Disorder

As its name suggests, intermittent explosive disorder is a condition in which a person explodes in anger. Poor regulation of emotions is seen in recurrent behavioural outbursts. They stem from a failure to inhibit aggressive impulses in response to provocation. Behaviours include temper tantrums, arguments, fights, physical aggression towards people, animals or property. This diagnosis is made when these behaviours occur twice weekly, on average, for a period of 3 months. The behavioural outbursts may also involve physical assault or destruction or damage to property occurring within a period of 12 months (American Psychiatric Association, 2013).

Conduct Disorder (CD)

More serious than ODD is CD. It attracts the attention of the law. Youth with CD repeatedly and repetitively behave in ways that infringe on the basic rights of others or that break social rules. They have significant difficulty following school rules and behaving in a socially appropriate manner. Behaviours in CD may include aggression towards people or cruelty to animals, vandalism, damage to property, theft and serious violation of societal norms (American Psychiatric Association, 2013). Like their counterparts with ODD, students diagnosed with CD have conduct problems that often lead to conflict with teachers and authority figures (American Psychiatric Association, 2013). Compared to typically developing peers, they are more likely to exhibit aggressive behaviours (Moffitt, 1993).

Anti-Social Personality Disorder

When a student has any of the above behavioural disorders and does not receive help to manage their inability to regulate their emotions and behaviours, over time they can become adults with an anti-social personality disorder. It is characterized by a pervasive pattern of disregard for, and violation of, the rights of others. Behaviours can include engaging in unlawful behaviours, repeated lying, impulsivity, repeated fights or assaults. These behaviours are very similar to what is observed in the above-mentioned behavioural disorders. What is salient in this personality disorder is blatant disregard for others’ safety and lack of remorse for wrongdoing. This personality disorder begins in childhood or early adolescence (i.e., occurring since age 15) and continues into adulthood. The student has to be at least age 18 and has a history of conduct disorder behaviours before age 15 for this diagnosis to be given (American Psychiatric Association, 2013).

Behavioural disorders that are untreated have short-term and long-term impact on the affected individual’s life (e.g., poor academic performance, suspension, expulsion, probation). ODD is a common precursor to the childhood-onset type of CD. Aggressive behaviours tend to predict delinquency, criminality and substance abuse (Fite et al., 2007; Loeber & Farrington, 2000; Piquero & Chung, 2001). Many children with conduct problems associated with behavioural disorders also show internalising behaviours such as depression and anxiety (Polier et al., 2012). Externalising disorders frequently co-occur with internalising disorders (Pesenti-Gritti et al., 2008). We call this comorbidity

What ‘Causes’ Behavioural Disorders?

An ecological perspective can help us to conceptualize the factors that can contribute to behavioural disorders. Urie Bronfenbrenner’s bioecological theory of development (Bronfenbrenner & Morris, 2006) elucidates the sociocultural influences that shape behaviour. It takes into account the effects of bi-directional interactions between the child and their environment which includes their family members, teachers, the community and society at large.

One factor is the child’s biological make-up and personality. Each person is born with unique hereditary traits (e.g., intelligence, health condition, self-esteem) that may predispose us to respond to situations in specific ways. Biological factors that can contribute to behavioural disorders are brain dysfunction (especially in the amygdala which regulates emotions), malnutrition or ill health. Negative emotionality, for example, has been identified as a heritable underlying trait common to both internalising and externalising behaviours (Rhee et al., 2015).

Environmental factors such as a student’s home and/or school may offer some clues to their behavioural problems. Discord within the family (e.g., parents’ marital issues, separation or divorce), absence or lack of parental supervision, maternal depression, abuse, harsh discipline and inconsistent parenting can mess up a child’s apprehension and acquisition of good behaviours. Within the school, negative social experiences (e.g., prejudice, discrimination, coercive discipline, bullying, victimization, peer conflicts, learning difficulties, academic failure) can also cause and exacerbate behavioural difficulties. Recent research suggests that genetic and environmental influences play a part in the comorbidity of depression, conduct problems and hyperactivity across the teenage years (Waszczuk et al., 2021).

The Singapore Context

The first large-scale mental health survey of 2,139 Singaporean children, aged 6-12 years, was conducted in 2007 by the Department of Child & Adolescent Psychiatry, Institute of Mental Health. Findings estimated a prevalence rate of 12.5% for emotional and behavioural problems amongst children in Singapore, excluding those who have special needs. This rate is comparable to that in the West and India (Woo et al., 2007). Of this, 5% of typically developing children exhibit externalising problems, such as aggression, hostility, and anti-social behaviour towards others. Apart from ADHD, the most common behavioural disorders referred to local mental health centers from schools are ODD and CD (Lee et al., 2003). Locally, more boys than girls have emotional and behavioural problems (Woo et al., 2007).


In Practice

Children behave differently in different contexts. A student’s behavioural issues may occur in one or multiple settings. In school, a student may display more behavioural difficulties in certain classes. Students who have behavioural disorders may also experience learning difficulties or have a learning disability. Educators will do well to take time to be acquainted with their needs and concerns, and to appreciate circumstances or events that may be stressful and overwhelming. The earlier a behavioural disability is identified or diagnosed and properly managed, the greater the likelihood that the affected youth will be able to regulate their behaviour.

An evidence-based practice for managing children with challenging behavioural difficulties in the school system is the use of FBA and positive behaviour interventions (Dutt et al., 2018). FBA is first conducted to determine the underlying function or purpose of behaviour in order to inform planning for behavioural remediation (Alberto & Troutman, 2013; Gresham et al., 2001). Effort is made to describe the problem behaviours in specific and observable terms (e.g., what does the student do when he has a melt-down in class) and to identify the environmental events (e.g., antecedents and consequences) linked to the behaviours (Gresham et al., 2001). Most importantly, FBA seeks to delineate the purpose or function of a problematic behaviour. For example, does a child throw a hissy fit to get attention or to escape from an undesired task? Understanding the function of a behaviour can help the teacher to plan and put in place positive strategies that teach the affected students more adaptive ways of meeting their needs (i.e., positive replacement behaviours that achieve what they hope to gain by their difficult behaviours). Positive behavioural interventions can translate into modeling and teaching socially appropriate behaviours that serve the same purpose as the challenging behaviours, pre-empting situational triggers that fuel problematic behaviours, creating conducive support for learning and reducing frustration, and minimizing rewards for negative behaviours (O'Neilll et al., 1997).

CBT is another empirically validated intervention for a range of internalising and externalising problems. In individual or group settings, children can be taught skills in anger management, emotional regulation and social problem-solving. In Singapore, the effectiveness of CBT-based intervention programs has been demonstrated in several studies (Ang, 2003; Krishnan et al., 2012; Ooi et al., 2007; Yeo & Choi, 2011). CBT-based programs teach children how thoughts, feelings and behaviours are connected, and how changing the way we think can influence and shape how we feel and respond to situations (Kendall, 2012). Apart from helping students to identify feelings and environmental triggers that engender strong emotions, CBT provides training in changing distorted thoughts or core beliefs that can then alter corresponding feelings and subsequent behaviours. In situations where there are bona fide reasons that prompt anger and the impulse to retaliate (e.g., when one is being bullied or unfairly treated), CBT teaches coping and problem-solving skills. CBT has been known to produce lasting effects as individuals learn a set of portable life skills that are applicable for a range of difficulties encountered in our daily lives.

REACH (Response, Early intervention and Assessment in Community mental Health), a community-based mental health service in Singapore, has adopted a CBT-based Social Problem-Solving Skills Training program (SPSST) to help children who have significant behavioural disorders (Ooi et al., 2013). Students are taught identification of feelings, anger coping skills, social-cognitive skills, and prosocial skills that can buffer them from behavioural problems (Ang & Ooi, 2003).

Schools can refer children who have behavioural disorders to REACH or MOE’s Psychological Services Branch for assessment and remediation support.



  • Behavioural disorders are chiefly characterized by an inability to regulate emotions and behaviours.
  • The most common behavioural disorders that are referred to local mental health centers are ODD and CD.
  • Behavioural disorders can co-occur with learning disabilities and internalising behaviours such as anxiety and depression.
  • It is important to get help early for children with behavioral disorders before the difficulties become chronic and deep-seated.
  • Functional behavioural assessment, positive behavioural interventions, and cognitive-behavioural therapy are empirically validated treatments for behavioural disorders.
  • Schools can access support from REACH and MOE Psychological Services Branch.



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Yeo, L.S. (2022, August 1). What do we know about Behavioural Disorders. Child and Human Development, Life@NIE SG®. https://nie.edu.sg/chd/topics/special-education/behavioural-disorders