Journal of Attention Disorders

Objective: To investigate the interaction between childhood trauma exposure with the catechol-O-methyltransferase (COMT) and dopamine receptor D4 (DRD4) polymorphisms in relation to neuropsychological measures in children with ADHD. Method: A cross-sectional examination of early traumatic experiences and the continuous performance test (CPT) were performed in 55 children with ADHD. Participants were also genotyped for the DRD4 exon III 48-bp variable number of tandem repeats (VNTR) polymorphism and the COMT Val¹⁵⁸-Met (rs4680) polymorphism. Results: There was significant interaction between the effects of the COMT genotype and trauma in commission errors. In participants with ADHD carrying the COMT Val/Val genotype, the group exposed to trauma showed significantly higher commission errors than the non-traumatized group. However, for the participants with other genotypes, no significant differences were found. Conclusion: This study suggests that there exists a genetic influence on the association between childhood trauma and the severity of inhibitory deficits in children with ADHD.

Objective: We examined the presence of cerebellar symptoms in ADHD and their association with behavioral markers of this disorder. Method: Sixty-two children with ADHD and 62 typically developing (TD) children were examined for cerebellar symptoms using the ataxia rating scale and tested using Conners’ Continuous Performance Test. Results: Children with ADHD had significantly more cerebellar symptoms compared with the TD children. Cerebellar symptom scores decreased with age in the ADHD group; in the TD group remained stable. In both groups, cerebellar symptoms were associated with parent-rated hyperactive/impulsive symptoms, variability of response time standard error (RT-SE) and increase of RT-SE as the test progresses. More variables were associated with cerebellar symptoms in the ADHD group including omission errors, overall RT-SE and its increase for prolonged interstimulus intervals. Conclusion: Our results highlight the importance of research into motor functions in children with ADHD and indicate a role for cerebellar impairment in this disorder.

Objective: ADHD is frequently detected in boys though there is no established cause. One possibility is that genes predisposing to ADHD have sexually dimorphic effects. With an aim to find out the reason for this male biasness, contribution of 14 functional polymorphisms was investigated in ADHD subjects. Method: Genomic DNA of probands, their parents, and ethnically matched controls was subjected to analysis of single-nucleotide polymorphisms and variable number of tandem repeats (VNTRs). Results: Case–control analysis revealed significant higher occurrence of DAT1 intron 8 VNTR “5R” allele (p = .028), DBH rs1108580 “A” allele (p = .027), and MAOA-u VNTR-rs6323 3R-T haplotype (p = .007) in male probands. Family-based analysis showed significant preferential transmission of Dopamine receptor D4 exon 3 VNTR-rs1800955 7R-T haplotype from parents to male probands (p = .008). Interaction between DBH gene variants and low enzymatic activity was also noticed, especially in male probands. Conclusion: Data obtained may partly answer the male biasness of ADHD.

Objective: When behavioral problems resulting from attentional difficulties present, often in preschool, it is unknown whether these problems represent preexisting altered brain development or new brain changes. This study examines whether infant sensory gating of auditory evoked potentials predicts parent-reported behavior at 40 months. Method: P50 sensory gating, an auditory evoked potential measure reflective of inhibitory processes in the brain, was measured in 50 infants around 70 days old. Parents, using the Child Behavior Checklist, reported on the child’s behavior at 40 months. Results: Controlling for gender, infants with diminished sensory gating had more problems later with externalizing behavior (F = 4.17, ndf = 1, ddf = 46, p = .047), attentional problems (F = 5.23, ndf = 1, ddf = 46, p = .027), and anxious/depressed symptoms (F = 5.36, ndf = 1, ddf = 46, p = .025). Conclusion: Diminished infant P50 sensory gating predicts attention symptoms 3 years later. These results support the hypothesis that preschool attentional dysfunction may relate to altered brain development that is detectable years prior to symptom onset.

Objective: Patients with ADHD have been suggested to have increased risks of allergic diseases but without consistent results, and limited studies about the association between ADHD and autoimmune diseases were noted in the literature. Method: Utilizing the Taiwan National Health Insurance Research Database, ADHD patients were identified and compared with age- and gender-matched controls (1:4). Results: In all, 8,201 participants were identified as having ADHD, and an increased prevalence of allergic diseases, including asthma (odds ratio [OR] = 1.53), allergic rhinitis (OR = 1.59), atopic dermatitis (OR = 1.53), and urticaria (OR = 1.39), compared with the control group. Although the comorbidity of autoimmune diseases with ADHD was low, ADHD patients had a significantly greater prevalence of ankylosing spondylitis (OR = 2.78), ulcerative colitis (OR = 2.31), and autoimmune thyroid disease (OR = 2.53) than the controls. Conclusion: Our results supported the association between ADHD and allergic/autoimmune diseases. The further studies will be required to clarify the underlying mechanisms.

Objective: The present study investigated differences in attentional networks in typically developing (TD) boys and boys with ADHD or autism spectrum disorder (ASD). In addition, we investigated the relationship between networks and the relationship with effortful control (EC). Method: An Attention Network Test was used to assess alerting, orienting, and executive attention in 25 TD boys, 25 boys with ADHD, and 25 boys with ASD. Results: In the absence of warning signals, boys with ADHD performed poorer than other children. In all groups, the orienting and executive control networks and the alerting and orienting networks interacted. Executive attention and EC were unrelated. Conclusion: Results provided evidence of impaired tonic alertness in ADHD and support the idea of functional integration of attentional networks. Finally, findings suggest that the link between EC reports and indices of neural systems involved in the effortful regulation of behavior may not be as unambiguous as previously thought.

Objective: To test the hypothesis that thyroid functioning would be uniquely associated with sluggish cognitive tempo (SCT) symptoms but not Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) symptoms of ADHD. Method: Serum thyroid stimulating hormone (TSH) was collected from a sample of psychiatrically hospitalized children (N = 570; ages = 6-12), with rates of TSH similar to those found in the normative pediatric population. Caregivers completed narrowband measures of SCT and ADHD symptoms and broadband measures of internalizing/externalizing symptoms. Results: A significant, positive relation was found between TSH concentration and SCT symptoms, but not between TSH and ADHD symptoms. Furthermore, regression analyses indicated that the association between TSH and SCT remained significant after controlling for child demographic characteristics, broadband measures of internalizing and externalizing symptoms, and ADHD symptoms. However, effects were small in magnitude. Conclusion: Although preliminary, results indicate that thyroid functioning may be related to SCT. Given the small effects, however, it is important for future research to examine other endocrine and biological correlates that may inform models of the developmental psychopathology of SCT.

This study focuses on whether risk avoidance in decision making depends on negative affect or it is specific to anxious individuals. The Balloon Analogue Risk Task was used to obtain an objective measure in a risk situation with anxious, depressive, and control individuals. The role of attentional networks was also studied using the Attentional Network Test–Interaction (ANT-I) task with neutral stimuli. A significant difference was observed between anxious and depressive individuals in assumed risk in decision making. We found no differences between anxious and normal individuals in the alert, orientation, and congruency effects obtained in the ANT-I task. The results showed that there was no significant relationship between the risk avoidance and the indexes of alertness, orienting, and control. Future research shall determine whether emotionally relevant stimulation leads to attentional control deficit or whether differences between anxious and no anxious individuals are due to the type of strategy followed in choice tasks.

Objective: To determine the trend in cortisol levels in children with ADHD treated with methylphenidate (MPH) and nontreated healthy controls over a 6-month period. Method: The morning salivary cortisol levels of 50 patients with ADHD (40 boys and 10 girls, mean age = 7.6 years) and 50 age- and gender-matched healthy controls were measured at baseline and at 1, 3, and 6 months from baseline. The neuropsychological performance of the ADHD patients was measured via administration of the Continuous Performance Test. Results: The cortisol levels of ADHD patients increased significantly after 1 month of MPH treatment before decreasing to an intermediate level, but were significantly positively correlated with neuropsychological performance throughout the 6-month treatment period. The cortisol levels of the controls did not change significantly over the 6-month period. Conclusion: MPH administration appears to positively influence the functioning of the hypothalamic–pituitary–adrenal axis in ADHD patients.