PubMed · 16006370
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Eric Taylor. 2005. ADHD.. https://doi.org/10.1080/15265160500194337
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Attention deficit hyperactivity disorder (ADHD) is a highly disabling, early onset childhood neurobehavioral disorder with a higher occurrence in boys as compared to girls. Pharmacological and molecular genetic studies have revealed the influence of dopaminergic and serotonergic systems in the etiology of the disorder. Monoamine oxidase A (MAOA) is a mitochondrial enzyme that regulates the dopaminergic signals in the pre-synaptic region. Polymorphism in the promoter region of the MAOA gene, which comprises of 30 bp repeats with repeat number varying between 2.5, 3.5, 4.5, and 5.5, has been shown to be associated with various neurobehavioral disorders including ADHD. This is the first study on Indian ADHD cases to validate an association between transmission of MAOA promoter polymorphism and risk of ADHD. We have analyzed the MAOA promoter polymorphism in a group of ADHD probands, their parents and ethnically matched controls by UNPHASED. Our findings indicate significant difference in the frequency of 3.5 repeat allele (P = 0.02) between cases and controls and preferential transmission of the short allele (3.5 repeat) from mothers to male ADHD probands (P = 0.005). We conclude that the short 3.5 repeat allele of the MAOA-u VNTR is probably associated with ADHD in our population and could be the reason for making boys prone to ADHD as compared to girls.
Few long-term studies have yet described neuropsychological outcome in preterm twins. Our aim was to assess, by long-term evaluation, neuropsychological outcome in preterm twins in order to define a correct follow-up program. Our study was a cohort one, with an index and a comparison group. Neonatal medical records of all preterm newborns admitted to our centre between 1991 and 1997 were reviewed and selected patients were recalled. The sample population included two matched groups of children aged 6-12 years, 86 twins and 86 singletons, submitted to paediatric, neurological, psychological, and ophthalmological examinations. Inclusion criteria were twin pregnancy and gestational age 27-36 weeks for index group; same gestational age, but single pregnancy, for the comparison group. All children underwent paediatric and neuropsychiatric examinations, cognitive assessment, and psychological evaluation by standardized tests for screening of learning specific disorders and language difficulties, and finally, ophthalmological examination. In order to study their role in predicting neuropsychological outcome, we examined some perinatal prognostic factors by statistical analysis. Unfavourable neuropsychological outcome was observed in 55/172 (32%) children, with different prevalence in the two groups, 42/172 (24%) in twins and 13/172 (8%) in singletons. Statistical analysis performed for examined prognostic factors showed significant differences in neuropsychological outcome with regard only to gestational age < 32 weeks, low birth weight, intraventricular haemorrhage, and periventricular leukomalacia. The incidence of neuropsychological diseases in the two groups showed significant difference about language and learning difficulties. Our data suggest that preterm twins represent a particular high-risk category of premature babies, mostly regarding the risk of so-called "minimal brain dysfunction", so a careful follow-up is recommended.
OBJECTIVE: The aim of this study was to examine the relationship between executive functions (EFs), as measured by neuropsychological tests, and symptoms of attention deficit hyperactivity disorder (ADHD) and comorbid behavior, as rated by parents and teachers. As intelligence and language ability are important covariates they were also assessed. METHOD: The sample consisted of 43 children aged 7-11 years who were referred for neuropsychological assessment at a tertiary clinical facility. Most of the children had the diagnosis of ADHD combined or inattentive type. Different aspects of EFs were assessed. RESULTS: EFs were not significantly related to symptoms of ADHD, but only to comorbid symptoms of depression and autistic symptomatology. Language ability rather than EFs best predicted teacher ratings of inattention. CONCLUSIONS: The results of the study do not support the EF theory of ADHD. The importance of screening for comorbid language disorders in children referred for ADHD is emphasized.