Journal of Abnormal Child Psychology

, Volume 42, Issue 1, pp 63-75

A Twin Study of the Relationships among Inattention, Hyperactivity/Impulsivity and Sluggish Cognitive Tempo Problems

  • Sara MoruzziAffiliated withThe Academic Centre for the Study of Behavioural Plasticity, Vita-Salute San Raffaele University Email author 
  • , Fruhlling RijsdijkAffiliated withMRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King’s College London
  • , Marco BattagliaAffiliated withDepartment of Psychiatry and Neurosciences, Laval University and Institut Universitaire en Santé Mentale de Québec

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We investigated the etiological relationships between the three ADHD dimensions of Inattentive Problems (INP), Hyperactivity-Impulsivity Problems (HIP) and Sluggish Cognitive Tempo (SCT) as measured by the CBCL 6–18 questionnaire. Multivariate models were applied to 398 twin pairs (374 boys and 422 girls) aged 8 to 17 years (M = 13.06, SD = 2.59) belonging to the population-based Italian Twin Registry. The INP, HIP and SCT problem scores were moderately-to-substantially (range 0.29–0.47) intercorrelated. The best fitting model showed that these 3 dimensions are correlated both at the genetic (correlations’ range: 0.65–0.83) and the environmental (correlations: 0.29 and 0.44) levels, but they are also distinct. While SCT showed moderate heritability and large non-shared environmental influences, variance for both INP and HIP was substantially explained by genetic influences. We also found evidence of negative sibling interaction for INP, implying that a given behavior in one twin leads to an opposite behavior in the co-twin. Our results support at the etiological level the findings of previous psychometric and longitudinal studies of ADHD, which yielded evidence of the 3 distinct—albeit correlated—problem dimensions of inattentiveness, hyperactivity-impulsivity, and sluggish cognitive tempo.


ADHD Sluggish cognitive tempo Multivariate twin studies CBCL