Vanshdeep Sharma

Developmental analysis of three aspects of information processing: Sustained attention, selective attention, and response organization

The development of cognitive abilities associated with Lunas (1973) three functional units of the brain was investigated in a sample of 62 children, ages 7 to 11 years, and 16 adults, ages 21 to 48 years. Selective attention, associated primarily with Lurias sensory‐input unit, showed no demonstrable development within the age ranges studied. However, sustained attention, presumably mediated through Lurias arousal unit and its ascending fibers to the cortex, as well as response organization, associated with Lunas organization‐and‐ planning unit, did reflect differential development Capacity for sustained attention showed no appreciable development between 7 and 11 years of age, but there was significant growth in this ability between age 11 and adulthood. Response organization, on the other hand, was found to develop most rapidly between 7 and 11 years of age. These findings are partially consistent with Lurias model of neurodevelopment as well as with research investigating the functional and physio...

Age-related changes in the association between serotonergic function and aggression in boys with ADHD.

The results of several studies have indicated an inverse relationship between central serotonergic (5-HT) mechanisms and aggression in animals and adults, but studies in children have yielded conflicting results. This study assessed 5-HT function, using a fenfluramine (FEN) challenge procedure, in an attempt to replicate a previously reported enhancement of the prolactin (PRL) response to FEN in aggressive relative to nonaggressive ADHD boys. The study failed to replicate the previous finding. Samples from both studies were then examined to reconcile the discrepant findings. The samples differed significantly in age. The entire group (n = 50) was then divided into older and younger subgroups and reanalyzed using a two-way (age-group x aggression) analysis of covariance (ANCOVA) controlling for plasma medication level. The ANCOVA generated a significant age-group x aggression interaction. Young aggressive boys had a significantly greater PRL response to FEN than young nonaggressive boys, but no such difference existed in the older age-group. These findings raise the possibility of different developmental trajectories in 5-HT function between aggressive and nonaggressive boys.

Plasma Cortisol and Aggression in Boys With ADHD

OBJECTIVE The results of several studies suggest an inverse relationship between cortisol secretion and aggressive behavior. This study examined basal plasma cortisol levels in aggressive and nonaggressive boys with attention-deficit hyperactivity disorder (ADHD). METHOD The subjects were 23 aggressive and 27 nonaggressive boys with ADHD, aged 7 to 11 years. After 3 days of a low monoamine diet and an overnight fast, an indwelling catheter was inserted into a forearm vein. Samples for plasma cortisol levels were obtained 105 and 115 minutes after insertion of the catheter. RESULTS A one-way analysis of covariance (ANCOVA) controlling for body mass revealed no significant difference in plasma cortisol between the aggressive and nonaggressive boys. Furthermore, when the children were alternatively divided on the basis of the presence or absence of a DSM-III-R diagnosis of conduct disorder, a one-way ANCOVA again revealed no significant difference in cortisol levels. CONCLUSIONS The hypothesized inverse relationship between cortisol secretion and aggressive behavior in boys with ADHD was not found. These findings are consistent with a large body of literature indicating that the biological substrate of aggression is complex and that the identification of biological laboratory markers of aggressive behavior is not a clinically useful strategy at this time.

Serotonin, Aggression, and Parental Psychopathology in Children With Attention-Deficit Hyperactivity Disorder

OBJECTIVE To explore the relationship between central serotonergic (5-HT) function and history of parental aggression in aggressive and nonaggressive boys with attention-deficit hyperactivity disorder (ADHD). METHOD History of psychiatric symptoms was assessed in the biological parents of 41 boys with ADHD. The relationship between 5-HT function in aggressive and nonaggressive probands, as assessed via the prolactin response to fenfluramine (FEN) challenge, and parental history of aggression was examined. RESULTS Aggressive boys with a parental history of aggressive behavior had a significantly lower prolactin response to FEN challenge than aggressive boys without a parental history of aggression. Nonaggressive boys had a prolactin response midway between those of the two aggressive subgroups, and their prolactin response did not vary as a function of parental aggression. Children subdivided on the basis of parental history of other psychiatric symptoms did not differ in their response to the FEN challenge. CONCLUSIONS These data indicate an association between parent aggressive behavior and lower 5-HT function in aggressive boys with ADHD but do not indicate the extent to which this association is environmentally and/or genetically transmitted. There may be different neurochemical mechanisms in familial and nonfamilial aggressive children, which have clinical implications for pharmacological interventions.

Inattentive and noninattentive ADHD children: do they constitute a unitary group?

Teacher-rated ADHD and normal control children were administered a continuous performance test (CPT), and were then further subdivided based upon the presence or absence of objectively assessed attentional deficits. In addition, children were assessed using several measures of cognitive and behavioral functioning. Attentional deficits were signficantly more prevalent among the ADHD group, but about half of the ADHD children showed no evidence of objectively assessed attentional dysfunction. Further group analyses indicated that ADHD children with objectively assessed attentional dysfunction appeared cognitively impaired, while ADHD children without objective evidence of attentional dysfunction had more conduct problems. CPT inattention was not related to the presence of cognitive impairments or conduct problems in the control group. These data must be considered preliminary because teacher ratings were the only source of diagnosis and a single measure of inattention was used. However, they suggest that two subtypes of ADHD children can be identified, one characterized by inattention and learning problems, and the other by conduct problems.

Differential diagnosis of ADHD: Are objective measures of attention, impulsivity, and activity level helpful?

Abstract The diagnostic utility of objective measures of inattention, impulsivity, and activity level was assessed by examining the classification of ADHD and non-ADHD patients, as well as normal children. Discriminant function analyses correctly classified 72.4% of subjects in the ADHD versus normal control comparison, and 66.2% in the ADHD versus non-ADHD comparison. Poor performance on objective measures was generally indicative of ADHD relative to normal controls, but “average” performance could not be used to rule out ADHD. Diagnostic classification indices were much lower in the ADHD versus non-ADHD patient discrimination. CPT-inattention scores had moderate sensitivity, but low specificity; CPT-impulsivity and actigraph scores had low sensitivity but high specificity. These findings are discussed in terms of the utility of these objective measures for assessing ADHD in clinical and nonclinical populations.

Children's Motor Activity: Reliability and Relationship to Attention and Behavior

This study examines the relationships between activity level, as measured using solid‐state actigraphs, continuous‐performance test‐measured attention, and behavior ratings in 73 nonreferred children. Activity level and attention, after controlling for age, were unrelated to each other, but were both related to teacher ratings of inattention and overactivity. Furthermore, activity level and attention were differentially related to IQ, academic achievement, and other teacher and parent ratings of behavior. These data suggest that objectively assessed activity level and attention are independent in nonreferred children. Further studies using these measures in clinical groups are necessary.

Parent and teacher ratings of attention-deficit hyperactivity disorder symptoms: implications for case identification

This study was designed to evaluate the relationship between the DSM-III criteria for attention-deficit disorder with hyperactivity (ADDH) and the DSM-III-R criteria for attention-deficit hyperactivity disorder (ADHD). Seventy-two children from an inner-city elementary school were evaluated using parent and teacher ratings on a scale consisting of the symptoms of DSM-III-R ADHD and oppositional-defiant disorder and DSM-III ADDH. Each child was also assessed using a psychometric test battery designed to examine cognitive function, attention, and activity level. Teacher ratings identified more children as DSM-III-R ADHD than DSM-III ADDH. Among these ADHD children, those who also met the ADDH criteria missed more targets on a continuous performance test (CPT) and were rated more overactive than controls. They also had a greater likelihood of being rated ADHD by parents. Children rated as meeting criteria for DSM-III-R ADHD, but not DSM-III ADDH, were not substantially different from controls on teacher ratings of overactivity, CPT performance, or parent ratings of ADHD, which raises questions regarding the nature and severity of the pathology in this group. J Dev Behav Pediatr 15:86–91, 1994. Index terms: diagnosis, DSM-III-R, attention-deficit disorder.

Attention, Response Inhibition, and Activity Level in Children: Developmental Neuropsychological Perspectives

Injury to the brain early in life frequently leads to a variety of cognitive and behavioral disturbances. The most common of these are mental retardation, deficits in linguistic, perceptual, motor, and attentional functioning, overactivity, and inhibitory control problems. Factors that have been implicated in causing early brain injury include, but are not limited to, perinatal anoxia or hypoxia, exposure to environmental toxins, infections, and malnutrition. Yet, it is noteworthy that many children present with the above problems in the absence of known neurologic insult.

Relationship between central serotonergic function and aggression in prepubertal boys: effect of age and attention-deficit/hyperactivity disorder

Data indicate that diminished central serotonergic (5-HT) function is related to aggression in adults, but discrepant findings in children suggest that age or the presence of attention-deficit/hyperactivity disorder (ADHD) may influence this relationship. This study examined whether age or ADHD affects the association between 5-HT and aggression in 7-11-year old clinically-referred boys. Forty-six boys were divided into non-aggressive ADHD, aggressive ADHD, and aggressive non-ADHD groups based on responses to interviews and ratings of behavior. Central 5-HT function was assessed by measuring the prolactin response to a 1-mg/kg oral dose of D,L-fenfluramine. There was no significant difference in the prolactin response across the three groups of boys. Furthermore, when examined dimensionally, prolactin response was largely unrelated to ratings of aggression, even after controlling for ADHD. Finally, age was not associated with prolactin response, and had no effect on the relationship between prolactin response and aggression. This study provides further evidence that there is no clear relationship between central 5-HT function and aggression in disruptive boys. Moreover, these data do not confirm the hypothesis that age or the presence of ADHD influence the relationship between 5-HT and childhood aggression.