Tom Humphries

Sleep Problems in Children With Attention‐Deficit/Hyperactivity Disorder: Impact of Subtype, Comorbidity, and Stimulant Medication

OBJECTIVE To determine the relationship of sleep problems to attention-deficit/hyperactivity disorder (ADHD), diagnostic subtype, comorbid disorders, and the effects of stimulant treatment. METHOD On the basis of clinical diagnostic interviews, children aged 6 to 12 years were assigned to 4 groups: unmedicated ADHD (n = 79), medicated ADHD (n = 22), clinical comparison (n = 35), and healthy nonclinical comparison (n = 36). These groups were compared on 2 sleep questionnaires completed by the parents that assessed current sleep problems and factors associated with sleep difficulties (i.e., sleep routines, sleep practices, child and family sleep history). RESULTS Factor analysis revealed 3 sleep problem categories: dyssomnias, parasomnias, and sleep-related involuntary movements. Linear regression analyses showed that (1) dyssomnias were related to confounding factors (i.e., comorbid oppositional defiant disorder and stimulant medication) rather than ADHD; (2) parasomnias were similar in clinical and nonclinical children; and (3) the DSM-IV combined subtype of ADHD was associated with sleep-related involuntary movements. However, sleep-related involuntary movements were more highly associated with separation anxiety. CONCLUSIONS The results suggest that the relationship between sleep problems and ADHD is complex and depends on the type of sleep problem assessed as well as confounding factors such as comorbid clinical disorders and treatment with stimulant medication.

Listening comprehension and working memory are impaired in attention-deficit hyperactivity disorder irrespective of language impairment.

This study investigated listening comprehension and working memory abilities in children with attention-deficit hyperactivity disorder (ADHD), presenting with and without language impairments (LI). A 4-group design classified a community sample (n = 77) of boys aged 9–12 into ADHD, ADHD + LI, LI, and Normal groups. Children completed tests of basic language and cognitive skills, verbal and spatial working memory, and passage-level listening comprehension. Multivariate analyses and post hoc comparisons indicated that ADHD children who did not have co-occurring LI comprehended factual information from spoken passages as well as normal children, but were poorer at comprehending inferences and monitoring comprehension of instructions. ADHD children did not differ from normal children in verbal span, but showed significantly poorer verbal working memory, spatial span, and spatial working memory. The ADHD + LI and LI groups were most impaired in listening comprehension and working memory performance, but did not differ from each other. Listening comprehension skills were significantly correlated with both verbal and spatial working memory, and parent–teacher ratings of inattention and hyperactivity/impulsivity. Findings that children with ADHD but no LI showed subtle higher-level listening comprehension deficits have implications for both current diagnostic practices and conceptualizations of ADHD.

Support for EKN1 as the susceptibility locus for dyslexia on 15q21.

Dyslexia has been linked to a number of chromosomal regions including 15q. Recently a gene, EKN1, with unknown function in the linked region, was identified via a translocation breakpoint. This gene was further supported as a susceptibility locus by association studies in a Finnish sample. We investigated the possibility of this locus as a susceptibility gene contributing to dyslexia, analyzed as a categorical trait, and analyzed key reading phenotypes as quantitative traits using six polymorphisms including the two previously reported to be associated with dyslexia. In our sample of 148 families identified through a proband with reading difficulties, we found significant evidence for an association to dyslexia analyzed as a categorical trait and found evidence of association to the reading and related processes of phonological awareness, word identification, decoding, rapid automatized naming, language ability, and verbal short-term memory. However, association was observed with different alleles and haplotypes than those reported to be associated in a Finnish sample. These findings provide support for EKN1 as a risk locus for dyslexia and as contributing to reading component processes and reading-related abilities. Based on these findings, further studies of this gene in independent samples are now required to determine the relationship of this gene to dyslexia.

Effect of Methylphenidate on Attention in Children with Attention Deficit Hyperactivity Disorder (ADHD): ERP Evidence

Methylphenidate is the most common treatment for attention deficit hyperactivity disorder (ADHD) and has been shown to improve attention and behaviour. However, the precise nature of methylphenidate on specific aspects of attention at different dose levels remains unclear. We studied methylphenidate effects in ADHD from a neurophysiological perspective, recording event-related potentials (ERPs) during attention task performance in normal controls and children with ADHD under different dose conditions. Twenty children with ADHD and 20 age matched controls were assessed with a continuous performance task requiring subjects to identify repeating alphabetic characters. ERPs and behavioural measures were recorded and analyzed for trials where a correct response was made. The ADHD group was assessed off drug (baseline) and on placebo, low (0.28 mg/kg) and high (0.56 mg/kg) dose levels of methylphenidate. The results showed that the ADHD group at baseline was more impulsive and inattentive than controls and had shorter P2 and N2 latencies and longer P3 latencies. Low dose methylphenidate was associated with reduced impulsivity (fewer false alarms) and decreased P3 latencies, whereas the higher dose level was associated with reduced impulsivity and less inattention (more hits), as well as increased P2 and N2 latencies and decreased P3 latencies. Amplitudes were unaffected and there were no adverse effects of the higher dose for any of the children. These results suggest differential dosage effects and a dissociation between dose levels and aspects of processing.

Spatial and emotional aspects of language inferencing in nonverbal learning disabilities.

Although subtle linguistic deficits have been postulated for children identified with nonverbal learning disabilities (NLD), there is little empirical evidence to support this contention. Two experimental language inferencing measures that have been demonstrated to be problematic for individuals with right hemisphere brain damage (RHBD) and one norm-referenced inferencing task were examined in three groups of children aged 9-13: (1) children with NLD (n = 14), (2) children with verbal impairments (VI) (n = 14), and (3) children without learning disabilities who served as controls (n = 19). The NLD and VI groups did not differ from one another on any of the three measures, indicating a generalized language inferencing deficit in the NLD group. Relative to the control group, however, the NLD group experienced specific difficulties with spatial and emotional inferencing. The implications for right hemisphere involvement in the NLD profile are examined in relation to the effects of working memory on inferential abilities.

A comparison of the effectiveness of sensory integrative therapy and perceptual-motor training in treating children with learning disabilities.

This study compared the effect of sensory integration therapy (SI), perceptual-motor training (PM) and no treatment (NT) on the performance of 103 children with learning disabilities and sensory integrative dysfunction, aged 58 to 107 months, who were randomly assigned to one of the two treatment groups or to no treatment. After receiving a total of 72 1-hour sessions of therapy for 3 hours per week, PM-treated subjects showed significant gains over the other two groups, primarily in gross motor performance. SI-treated subjects showed an advantage in motor planning. There were no accompanying group differences in visual perception, handwriting readiness, copying ability, cognitive, academic, language and attentional skills or in self-concept. These findings demonstrate motor gains resulting from motor treatments without carry-over to functional skills and abilities more directly associated with school performance. J Dev Behav Pediatr 13:31–40, 1992. Index terms: motor treatments, learning disabilities.

Association of reading disabilities with regions marked by acetylated H3 histones in KIAA0319

Reading disabilities (RDs) have been associated with chromosome 6p with recent studies pointing to two genes, DCDC2 and KIAA0319. In this study, markers across the 6p region were tested for association with RD. Our strongest findings were for association with markers in KIAA0319, although with the opposite alleles compared with a previous study. We also found association with markers in VMP, but not with DCDC2. Current evidence indicates that differential regulation of KIAA0319 and DCDC2 contributes to RD, thus we used chromatin immunoprecipitation coupled with genomic tiling arrays (ChIP‐chip) to map acetylated histones, a molecular marker for regulatory elements, across a 500 kb genomic region covering the RD locus on 6p. This approach identified several regions marked by acetylated histones that mapped near associated markers, including intron 7 of DCDC2 and the 5′ region of KIAA0319. The latter is located within the 70 kb region previously associated with differential expression of KIAA0319. Interestingly, five markers associated with RD in independent studies were also located within the 2.7 kb acetylated region, and six additional associated markers, including the most significant one in this study, were located within a 22 kb haplotype block that encompassed this region. Our data indicates that this putative regulatory region is a likely site of genetic variation contributing to RD in our sample, further narrowing the candidate region.

The KIAA0319-like (KIAA0319L) gene on chromosome 1p34 as a candidate for reading disabilities.

A locus on chromosome 1p34-36 (DYX8) has been linked to developmental dyslexia or reading disabilities (RD) in three independent samples. In the current study, we investigated a candidate gene KIAA0319-Like (KIAA0319L) within DYX8, as it is homologous to KIAA0319, a strong RD candidate gene on chromosome 6p (DYX2). Association was assessed by using five tagging single nucleotide polymorphisms in a sample of 291 nuclear families ascertained through a proband with reading difficulties. Evidence of association was found for a single marker (rs7523017; P=0.042) and a haplotype (P=0.031), with RD defined as a categorical trait in a subset of the sample (n=156 families) with a proband that made our criteria for RD. The same haplotype also showed evidence for association with quantitative measures of word-reading efficiency (i.e., a composite score of word identification and decoding; P=0.032) and rapid naming of objects and colors (P=0.047) when analyzed using the entire sample. Although the results from the current study are modestly significant and would not withstand a correction for multiple testing, KIAA0319L remains an intriguing positional and functional candidate for RD, especially when considered alongside the supporting evidence for its homolog KIAA0319 on chromosome 6p. Additional studies in independent samples are now required to confirm these findings.

Mediators of the Risk for Problem Behavior in Children with Language Learning Disabilities

A developmental-organizational perspective was employed to explore underlying risk for problem behavior in children with language learning disabilities. The independent and relative influences of social discourse and social skills on problem behavior were examined in 50 children with language learning disabilities (LLD) and 50 control children (children without LLD) aged 8 to 12 years. Hierarchical regression analyses revealed that when examined independently, both impaired social discourse skill and poor social skills accounted for the negative effect of LLD status on childrens problem behavior. When social discourse and social skills were examined simultaneously in relation to problem behavior, social discourse no longer retained its predictive value. This result suggests that childrens impaired social interactional functioning is central to the development of behavioral symptomatology. However, the importance of social discourse cannot be overlooked, given the significant correlation between social discourse and social skills ratings. Though these results are correlational in nature, it is argued that the impaired communicative competence of some children with LLD may contribute to poor social skills that ultimately manifest themselves as more clinical problem behaviors characterized by internalizing and externalizing symptomatology. Finally, differences were confirmed in social discourse performance, social skills, and problem behaviors between the children with LLD and the control group children. Findings emphasize the importance of the routine assessment and monitoring of broader social discourse skills, in addition to social competence, in children with LLD.

Attention deficit hyperactivity disorder : does cognitive behavioral therapy improve home behavior?

This study evaluates the effectiveness of cognitive behavioral therapy (CBT) in improving the home behavior of children with attention deficit hyperactivity disorder (ADHD). Twenty-five boys (age 7 to 13) with a diagnosis of ADHD were randomized to a CBT or supportive therapy control group. Outcome measures included parent and teacher ratings of the child on the Behavior Problem Checklist-Attention Problem Subscale (BPC-AP), and the Self-Control Rating Scale (SCRS), parent ratings on the Modified Werry Weiss Activity Scale, and child ratings on the Piers Harris Self-Concept Scale and Matching Familiar Figures Task. Data were analyzed using a two-way analysis of variance for main effects. A significant improvement favoring CBT was found on the Werry Weiss Scale, which measures the parents perception of the childs hyperactivity in the home, and the childs rating of his/her self-esteem on the Piers Harris Self-Concept Scale. Other outcome measures did not demonstrate statistical differences. This research provides support for the use of CBT in children with ADHD. CBT was found to improve the parents perception of the childs hyperactivity in the home as well as the childs self-esteem.