Impulsive aggression in adults with attention-deficit/hyperactivity disorder

J. H. Dowson, A. D. Blackwell
Article first published online: 19 AUG 2009

DOI: 10.1111/j.1600-0447.2009.01460.x

© 2009 John Wiley & Sons A/S
Issue
Acta Psychiatrica Scandinavica
Volume 121, Issue 2, pages 103–110, February 2010
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How to CiteAuthor InformationPublication History

Keywords:

adult attention deficit/hyperactivity disorder;aggression

Abstract
Dowson JH, Blackwell AD. Impulsive aggression in adults with attention-deficit/hyperactivity disorder.

Objective:  DSM-IV criteria for attention-deficit/hyperactivity disorder (ADHD) include examples of ‘impulsivity’. This term can refer to various dysfunctional behaviours, including some examples of aggressive behaviour. However, impulsive aggression is not included in the DSM-IV criteria for ADHD. The associations of impulsive aggression with ADHD were investigated.

Method:  Seventy-three male adults with DSM-IV ADHD, and their informants, completed questionnaires. Impulsive aggression was assessed by ratings of two criteria for borderline personality disorder (BPD), involving hot temper and/or self-harm.

Results:  Logistic regression indicated that features of DSM-IV ADHD were predictors of comorbid impulsive aggression. However, compared with ADHD features, verbal IQ and comorbid psychopathology were more strongly associated with impulsive aggression.

Conclusion:  The findings support the inclusion of features of impulsive aggression, such as hot temper/short fuse, in the ADHD syndrome in adults. These overlap with features of BPD. The findings inform the selection of research samples.

Significant outcomes
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In male adults with ADHD, the main domains of DSM-IV ADHD were predictors of comorbid impulsive aggression.
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Compared with ADHD features, verbal IQ and comorbid psychopathology were more strongly associated with impulsive aggression.
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In adults, impulsive aggression can be considered as a part of the ADHD syndrome, which overlaps with features of borderline personality disorder. The findings are relevant for the selection of research samples.

Limitations
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There is limited reliability for current assessments of ADHD.
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Heterogeneity of subjects with ADHD can involve ADHD features, IQ, comorbidity and previous treatment.
• 
The present study did not include women.

Introduction
There is uncertainty about the status of impulsive aggression as a feature of the syndrome of attention-deficit/hyperactivity disorder (ADHD), because aggression is found in the context of disorders which are commonly comorbid with ADHD, such as conduct disorder (CD) and, in adults, antisocial and borderline personality disorders (1). The syndromal context of impulsive aggression in subjects with ADHD may have important implications for the selection of research samples and the efficacy of drug treatments and other interventions which have a specific role for the treatment of ADHD.

The DSM-IV ADHD criteria (2) include examples of ‘impulsivity’. This term can refer to several variably co-occurring behaviours with different neurobiological substrates, which are features of several psychiatric syndromes (3–6). Impulsivity has been considered to be reflected by some examples of impaired focusing on a task, rapid poorly planned responses to stimuli, lack of perseverance and disorganization.

Impulsivity has also been associated with some forms of aggression (7) and one definition of impulsivity is ‘a lowered threshold for motoric actions, particularly aggressive behaviour, in response to environmental stimuli’ (8). Aggression can be reflected by verbal aggression (i.e. expressions of anger and/or threats of violence to self or others), aggression against property, autoaggression (i.e. various forms of self-harm) and physical aggression to others (9). Although impulsive aggression is not included in the DSM-IV criteria for ADHD, aggression has often been reported in subjects with ADHD (10–13) and is included in the ‘Utah’ criteria for adult ADHD (14). Also, aggression in subjects with ADHD has been reported to be modified by drug treatments for ADHD (15, 16).

Various associations with aggression have been reported in subjects with ADHD. In children with ADHD, impulsivity and emotional lability predicted adult antisocial behaviour (17) and, in children and young adults, the DSM-IV ‘combined’ ADHD type predicted more self-harm and antisocial behaviour compared with the ‘inattentive’ type (18, 19). In addition, ADHD has been associated with increased risk of suicidal ideation in female adolescents (20) and of attempted and completed suicide in male adolescents and young adults (19, 21, 22). In another study in children, ADHD comorbid with CD predicted more physical aggression compared with ADHD alone, while comorbid oppositional defiant disorder (ODD) predicted more verbal aggression (23, 24). However, there are conflicting claims about the associations of ADHD with aggression in the absence of comorbid disorders which involve aggression, in particular, of CD and, in adults, of DSM-IV ‘cluster B’ personality disorders (PDs) (25). The latter include borderline personality disorder (BPD), some features of which can be considered as examples of impulsive aggression, i.e. temper outbursts, hitting people, throwing things and some examples of repeated self-harm. Although a follow-up study to adulthood of clinic-referred boys found that CD, but not ADHD, significantly predicted antisocial PD (26), another follow-up study involving official arrest data found that even ADHD boys with ‘low defiance ratings’ had significantly higher offender rates than normal controls (27).

Aims of the study
The aim was to investigate associations of impulsive aggression in adults with ADHD, to evaluate the validity of impulsive aggression as a part of the ADHD syndrome in adults and to inform the selection of subjects for future research into treatments for ADHD.

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