- Comorbid ADHD and conduct disorder were identified in a 15-year-old with severe aggression and domestic violence after standard psychosocial interventions failed.
- Methylphenidate titrated to 36 mg daily produced rapid, sustained reductions in impulsivity, antisocial behaviour and complete cessation of domestic violence.
- Objective measures normalised: QbTest activity and impulsivity percentiles fell to low ranges and parent Conners-4 conduct scores dropped to zero.
Cureus. 2026 Sep 5;18(9):e115810. doi: 10.7759/cureus.115810. eCollection 2026 Sep.
ABSTRACT
Attention-deficit hyperactivity disorder (ADHD) and conduct disorder (CD) are diagnoses that are frequently comorbid. CD is characterised by persistent dissocial, aggressive, and defiant behaviors that defy age-appropriate expectations. This is the case of a 15-year-old male adoptee referred to Tier 3 Child and Adolescent Mental Health Service (CAMHS) for severe aggression, impulsivity, and domestic violence. The patient exhibited coercive control toward his mother, physical violence involving weapons, and property damage, necessitating police involvement and risking family placement breakdown. Following a failure of psychosocial interventions, the patient underwent the Quantified Behavioral (Qb) Test and Conners-4 assessments and review by a consultant psychiatrist confirming ADHD and conduct disorder diagnosis. Methylphenidate was initiated and titrated to 36mg daily. Outcomes were significant. Within one month, antisocial behaviors reduced markedly. At seven months, domestic violence had ceased, and social care involvement ended. The patient successfully completed his General Certificates of Secondary Education (GCSE). Repeat testing on medication showed normalisation of scores: QbTest activity dropped to the 23rd percentile and impulsivity to the 21st percentile. Crucially, parent-rated Conners-4 scores for CD dropped to zero. This case highlights the importance of identifying and treating underlying ADHD in adolescents presenting with severe conduct issues. Higher doses of methylphenidate are often cited as beneficial for CD symptom reduction; this patient achieved remission of aggression at 36mg/day. The case shows that delaying ADHD diagnosis in favor of solely managing behavioral conduct symptoms can risk education and family stability. Treating the ADHD effectively mitigated the emotional dysregulation and violence and reduced the negative impact on this patient during a crucial period of his life as he was completing high school. This case highlights the importance of considering comorbid ADHD and CD in patients presenting with impulsive behaviours and aggression as their primary presenting complaints. Appropriate management with methylphenidate could have a significant therapeutic effect on these patients and their antisocial behaviours.
PMID:42835890 | PMC:PMC13635929 | DOI:10.7759/cureus.115810
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