Movement disorders: neurodevelopment and neurobehavioural expression

Relations between fine motor skills and intelligence in typically developing children and children with attention deficit hyperactivity disorder

BACKGROUND

The embodied cognition hypothesis implies a close connection between motor and cognitive development. Evidence for these associations is accumulating, with some studies indicating stronger relations in clinical than typically developing samples.

AIMS

The present study extends previous research and investigates relations between fine motor skills and intelligence in typically developing children (n = 139, 7-13 years) and same-aged children with attention deficit hyperactivity disorder (ADHD, n = 46). In line with previous findings, we hypothesized stronger relations in children with ADHD than in typically developing children.

METHODS AND PROCEDURE

Fine motor skills were assessed using the standardized Movement Assessment Battery for Children. Intelligence was measured with the standardized Wechsler Intelligence Scale for Children.

OUTCOMES AND RESULTS

Regression analyses indicated significant relations between fine motor skills and full-scale IQ, perceptual reasoning, working memory, and processing speed. Moderation analyses identified stronger relations between fine motor skills and full-scale IQ, perceptual reasoning, and verbal comprehension in children with ADHD compared to typically developing children.

CONCLUSIONS AND IMPLICATIONS

Results suggest a close relation between fine motor skills and intelligence in children with and without ADHD, with children diagnosed with ADHD showing stronger relations. Findings support combined motor-cognitive interventions in treating children with ADHD.

ADHD and poor motor performance from a family genetic perspective

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is frequently accompanied by motor problems (MPs). We investigated a possible shared etiology between the two traits in the Dutch sample of the International Multicenter ADHD Genetics study comprising 275 children with ADHD and their affected or unaffected sibling and 146 unrelated control children.

METHOD

Exploratory data analysis and bivariate structural equation modeling were used to estimate the familiality of MP rated by parents (Developmental Coordination Disorder Questionnaire [DCD-Q]) or teachers (Groningen Motor Observation Scale [GMO]) and to determine the familial and environmental correlation between MP and ADHD. Furthermore, the nature of the familiality was explored by studying the siblings of ADHD-affected children.

RESULTS

The ADHD-affected children had significantly more MP than their unaffected siblings, who in turn had significantly more MP than the control subjects. The familial component of MP measured by DCD-Q and GMO was 47% and 22%, respectively. The familial correlation between motor performance measures and ADHD was -0.38 for DCD-Q and -0.40 for GMO. Our data suggested that co-occurrence of ADHD and MP possibly marks a distinct subtype of ADHD, rather than signaling increased severity of disease.

CONCLUSIONS

Attention-deficit/hyperactivity disorder and MP have a common basis that may be due to genetic factors and/or shared environmental factors. Attention-deficit/hyperactivity disorder accompanied by MP may behave like a distinct subtype of ADHD, but more research will be needed to support that hypothesis.

Motor coordination problems in children and adolescents with ADHD rated by parents and teachers: effects of age and gender

OBJECTIVE

ADHD is frequently accompanied by motor coordination problems. However, the co-occurrence of poor motor performance has received less attention in research than other coexisting problems in ADHD. The underlying mechanisms of this association remain unclear. Therefore, we investigated the prevalence of motor coordination problems in a large sample of children with ADHD, and the relationship between motor coordination problems and inattentive and hyperactive/impulsive symptoms. Furthermore, we assessed whether the association between ADHD and motor coordination problems was comparable across ages and was similar for both genders.

METHOD

We investigated 486 children with ADHD and 269 normal controls. Motor coordination problems were rated by parents (Developmental Coordination Disorder Questionnaire) and teachers (Groningen Motor Observation Scale).

RESULTS

Parents and teachers reported motor coordination problems in about one third of children with ADHD. Problems of fine and gross motor skills, coordination skills and motor control were all related to inattentive rather than hyperactive/impulsive symptoms. Relative to controls, motor coordination problems in ADHD were still present in teenagers according to parents; the prevalence diminished somewhat according to teachers. Boys and girls with ADHD were comparably affected, but motor performance in controls was better in girls than in boys.

CONCLUSIONS

Motor coordination problems were reported in one third of children with ADHD and affected both boys and girls. These problems were also apparent in adolescents with ADHD. Clinicians treating children with ADHD should pay attention to co-occurring motor coordination problems because of the high prevalence and the negative impact of motor coordination problems on daily life.