Search tips
Search criteria

Results 1-5 (5)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
Document Types
1.  Evidence for specificity of ERP abnormalities during response inhibition in ADHD children: A comparison with Reading Disorder children without ADHD 
Brain and cognition  2009;72(2):228-237.
Executive function and working memory deficits are not only present in ADHD, but also in Reading Disorder (RD). Here, high-density ERPs were recorded during the Stop Signal Task in 53 children and adolescents: An ADHD-combined type group, a group with RD, and a healthy control group. The ADHD-C group displayed unique abnormalities of the frontal N200. Both healthy controls and RD groups showed a success-related right frontal N200 modulation, which was absent in the ADHD group. Second, for Success Inhibition trials, the ADHD-C had smaller right frontal N200 waves relative to healthy controls, while the RD group didn't. In contrast, NoGo-P3 abnormalities were present both in the ADHD-C and RD groups. Impaired early response inhibition mechanisms, indexed by the frontal N200, appear to be limited to ADHD-C. In contrast, deficits in later cognitive control and error monitoring mechanisms, indexed by the NoGo-P3, appear to be present in both conditions.
PMCID: PMC4321824  PMID: 19850394
ADHD; Reading Disorder; Event-Related Potentials; Stop Signal Task; Inhibitory Control; N200; NoGo-P3
2.  Neuroanatomical and Neuropsychological Correlates of the Cerebellum in Children with Attention-Deficit/Hyperactivity Disorder – Combined Type 
Studies of healthy individuals and those with cerebellar damage have implicated the cerebellum in a variety of cognitive and behavioral processes. Reduced cerebellar volume has been found in children with ADHD and differentially related to behavioral outcomes. In the current study, we sought to determine if reduced cerebellar vermis volume was present in children with ADHD-Combined type (ADHD-C) compared to controls and whether volume related to parent and teacher reported levels of ADHD symptomatology.
2T MRI images and parent and teacher reported ADHD symptoms were acquired for 32 children diagnosed with ADHD-C and 15 typically-developing controls. Participants were right-handed, had no comorbid diagnoses of learning disabilities, conduct disorder, or affective/mood disorder, and were between the ages of 9 and 15.
Participants with ADHD-C showed significantly reduced volume in the posterior inferior vermis compared to controls. No statistically significant differences were observed for cerebral volume, anterior vermis volume, posterior superior volume, or total cerebellar volume. Regression analyses indicated that a significant amount of the variance in parent-reported BASC-II Hyperactivity and Attention and Conners’ Restless/Impulsive ratings was explained by volume of the posterior inferior vermis.
Consistent with previous studies, children with ADHD had reduced volume in the posterior inferior vermis. New findings emerged with reduced volume of the posterior inferior vermis predicting significant amount of the variance in parent-reported hyperactivity, attention, and restlessness/impulsivity. Thus, symptoms of hyperactivity and inattention in ADHD may be partially explained by reduced volume of the cerebellar vermis and its connections within the cerebrum.
PMCID: PMC3104210  PMID: 21621143
ADHD; cerebellum; vermis; hyperactivity; attention
3.  Developmental outcomes in Malawian children with retinopathy-positive cerebral malaria 
To assess children with retinopathy-positive cerebral malaria (CM) for neurocognitive sequelae.
Participants were selected from an ongoing exposure–control study. Eighty-three Malawian children averaging 4.4 years of age and diagnosed with retinopathy-positive CM were compared to 95 controls. Each child was classified as delayed or not using age-based norms for the Malawi Developmental Assessment Tool (MDAT) for developmental delay on the total scale and for the domains of gross motor, fine motor, language and social skills. Groups were also compared on the Achenbach Child Behaviour Checklist (CBCL) (1.5–5 years).
Children with retinopathy-positive CM were delayed, relative to the comparison group, on MDAT total development (P = 0.028; odds ratio or OR = 2.13), with the greatest effects on language development (P = 0.003; OR = 4.93). The two groups did not differ significantly on the Achenbach CBCL internalizing and externalizing symptoms total scores. Stepwise regression demonstrated that coma duration, seizures while in hospital, platelet count and lactate level on admission were predictive of assessment outcomes for the children with retinopathy-positive CM.
Children who suffer retinopathy-positive CM at preschool age are at greater risk of developmental delay, particularly with respect to language development. This confirms previous retrospective study findings with school-age children evaluated years after acute illness. The MDAT and the Achenbach CBCL proved sensitive to clinical indicators of severity of malarial illness.
PMCID: PMC3213405  PMID: 21143354
malaria; retinopathy; child development; language; motor function; social skills; brain; Malawi; Malawian developmental assessment tasks; Achenbach child behaviour checklist; Socioeconomic status; Africa
4.  Response Inhibition and Academic Abilities in Typically Developing Children with Attention-Deficit-Hyperactivity Disorder-Combined Subtype 
Research in Attention-Deficit/Hyperactivity Disorder (ADHD) generally utilizes clinical samples or children with comorbid psychiatric diagnoses. Findings indicated that children with ADHD experience academic underachievement and poor performance on measures of response inhibition (RI). Less is known, about the neuropsychological profile of typically developing children with ADHD. The aim of the current study was twofold: (1) determine if academic skills and RI were impaired in typically developing children with ADHD-combined subtype (ADHD-C) and (2) determine to what extent RI may predict academic abilities. Children with ADHD-C did not differ on any academic domain from controls. Children with ADHD-C performed more poorly than controls on RI measures. Regression analyses suggest that Written Expression ability was significantly influenced by RI. No other academic domain was related to RI. Results suggest that children with ADHD-C may experience impairments in RI despite adequate academic functioning. Impaired RI is not solely responsible for difficulties found in academic skills in ADHD-C.
PMCID: PMC2957960  PMID: 20605842
ADHD; Achievement; Executive functions; Response inhibition
5.  An MRI Study of the Cerebellar Vermis in Chronically-Treated and Treatment-Naïve Children with ADHD-Combined Type 
Biological psychiatry  2009;65(7):620-624.
Because of its dense connections to the prefrontal cortex and basal ganglia, the cerebellum is thought to play an important role in cognition. Numerous MRI studies have found abnormalities in the cerebellum in children with ADHD. While some studies in animal and human models suggest that the certain brain structures are affected by chronic stimulant medication, it is unclear whether the cerebellum is also affected. The purpose of the current study was to determine if cerebellar morphology was different in treatment-naïve vs. chronically-treated children with ADHD.
There were 32 boys and 15 girls total (N = 47) that comprised three groups: ADHD-C children with no history of stimulant medication treatment (n = 14), ADHD-C children chronically treated with stimulant medication (n = 18), and typically developing control children (n = 15).
Treatment-naïve children with ADHD had significantly smaller area in the posterior inferior vermis (lobules VIII-X) than both chronically-treated children with ADHD (p = .004) and typically developing controls (p = .001). No differences were observed between chronically-treated children with ADHD and controls.
The results from this study suggest that chronic stimulant treatment may normalize the development of important areas of the cerebellar vermis in children with ADHD.
PMCID: PMC2675536  PMID: 19150052
ADHD; cerebellum; MRI; medication treatment; vermis

Results 1-5 (5)