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Biomedical subjects

R Schachar

Publications and source records attributed to R Schachar.

14 recordsLinked to original sources
PubMed1992

Methylphenidate and cognitive perseveration in hyperactive children.

Effects of methylphenidate on cognitive flexibility were investigated in 26 children with Attention Deficit Hyperactivity Disorder (ADHD), by assessing perseverative errors on the Wisconsin Card Sorting Test (WCST) and the emergence of clinical symptoms indicative of cognitive perseveration. A double-blind, placebo-control, randomized crossover design was used in which each child was assessed twice in each drug condition (placebo, 0.3 and 1.0 mg/kg). Results indicated that methylphenidate increased perseverative errors on the first assessment but decreased them on the second; clinical symptoms of perseveration occurred at both assessments. Findings suggest that MPH may reduce cognitive flexibility temporarily in some ADHD children.

Attention↗
PubMed1991

Childhood hyperactivity.

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Attention Deficit Disorder with Hyperactivity↗
PubMed1990

Are hyperactive children deficient in attentional capacity?

A dual task was used to study attentional capacity in three groups: in 6- to 12-year-old boys with attention deficit disorder plus hyperactivity (ADDH) or with ADDH and conduct disorder, and in normal children. Subjects performed a primary-choice reaction-time task first without and then with a secondary task that also required a response. Our prediction that the reaction time of ADDH subjects to the secondary task would increase more with increasing temporal overlap of the primary and secondary stimuli, if they were deficient in capacity, was not supported. However, the performance of ADDH subjects on the primary task deteriorated more than that of control subjects with the introduction of the secondary task, indicating a greater concurrence cost or a different allocation policy. Moreover, ADDH subjects had longer reaction times to the secondary task, indicating greater refractory effects or difficulty shifting capacity from primary- to secondary-task processes.

Attention↗
PubMed1990

Oppositional disorder in children: a validation study comparing conduct disorder, oppositional disorder and normal control children.

Subjects with oppositional disorder (OD, N = 21) and conduct disorder (CD, N = 22) were compared with normal controls (NC, N = 20) to determine whether OD is a distinct disorder. OD subjects exhibited high rates of associated attention deficit, emotional and learning disorders. Compared with NC, OD subjects had high rates of problems in social relationships and came from families characterized by marital fights, dysfunction, and paternal psychopathology. Compared with CD, OD was less often characterized by undersocialization and separations from fathers and more often characterized by dissatisfaction in the marital relationship. These results suggest that OD is a variant of CD rather than of normality.

Achievement↗
PubMed1990

Hyperactivity and parental psychopathology.

The association of child hyperactivity and parental psychopathology was explored by establishing lifetime DSM-III diagnoses and histories of childhood hyperactivity among the parents of boys, aged 7-11 yrs, in five diagnostic groups: attention deficit disorder with hyperactivity (ADDH), conduct disorder (CD), ADDH + CD, emotional disorder (ED) and no disorder (NC). These groups were differentiated by a family history of parental psychopathology or childhood hyperactivity. ADDH + CD, CD and ED groups all had significantly higher rates of parental psychopathology than the ADDH and NC groups, for which rates were similar. Significantly more boys in the ADDH, CD and ADDH + CD groups had family histories of parental childhood hyperactivity than did boys in the ED and NC groups.

Anxiety Disorders↗
PubMed1990

Aspartame: effects on learning, behavior, and mood.

The effect of aspartame on the learning, behavior, and mood of children was evaluated in two experiments. After an overnight fast and a standard breakfast, 20 healthy 9- to 10-year-old children were given the treatments in a double-blind crossover design at 10:30 AM. Lunch was served at 12:00 noon. In experiment 1, the treatment consisted of an ice slurry of strawberry Kool-Aid containing 1.75 g/kg of carbohydrate (polycose) plus either aspartame (34 mg/kg) or the equivalent sweetness as sodium cyclamate and amino acids as alanine. In experiment 2, the treatment consisted of a drink of cold unsweetened strawberry Kool-Aid, containing either 1.75 g/kg of sucrose or 9.7 mg/kg of aspartame. Measures of associative learning, arithmetic calculation, activity level, social interaction, and mood were unaffected by treatment in experiment 1. In experiment 2, the only significant treatment effect was that on the frequency of minor and gross motor behaviors, which were less frequent after the consumption of sucrose than after aspartame. Thus, the effect of aspartame on the short-term behavior of healthy 9- to 10-year-old children appears to be related to its absence of metabolic consequences rather than to its amino acid composition and putative neurochemical impact.

Affect↗
PubMed1989

Effects of event rate and display time on sustained attention in hyperactive, normal, and control children.

Two experiments were conducted to determine whether hyperactive boys have a unique deficit in sustained attention. Groups with DSM-III diagnoses of attention deficit disorder (ADDH), conduct disorder (CD), ADDH + CD, and learning disorder were compared with normal controls on the Continuous Performance Task. In Experiment 1, stimulus presentation rate (stimulus onset asynchrony, SOA) and display time were varied to manipulate attentional demand, and speed and accuracy of performance were measured. The ADDH group was uniquely affected, with less accurate performance at the fastest and slowest SOA. To distinguish the effects of time on task and SOA, the duration of each SOA condition was held constant in Experiment 2. The poorer performance of the ADDH group at the fastest SOA was no longer evident. This finding indicates that the deficit of sustained attention in boys who have ADDH is associated with a greater susceptibility to refractory effects, which is influenced by practice.

Arousal↗
PubMed1988

Attaining and maintaining preparation: a comparison of attention in hyperactive, normal, and disturbed control children.

The hypothesis that hyperactive children have a deficit in sustained attention was investigated. Eighteen children who had attention deficit disorder with hyperactivity (ADDH), aged 7 to 11 years, were compared with children who had conduct disorder (n = 15), mixed conduct disorder and ADDH (n = 26), emotional disorder (n = 18), or learning disability (n = 22), and with normal controls (n = 15). The subjects were tested on three versions of the Continuous Performance Task. Sustained attention was assessed from performance with increasing time on task and from ability to prepare attention in response to a warning. Performance of all subjects deteriorated with increasing time and improved with the opportunity to prepare attention. Hyperactive subjects were not more adversely affected by increasing time, nor did they benefit less than controls from the opportunity to prepare attention. Data reanalysis after rediagnosis according to ICD-9 criteria did not change the results. This study did not confirm the hypothesis that hyperactive children have a unique sustained attention deficit.

Affective Symptoms↗
PubMed1987

Which boys respond to stimulant medication? A controlled trial of methylphenidate in boys with disruptive behaviour.

Thirty-eight boys, referred for psychiatric treatment because of serious problems of behaviour, underwent a double-blind, placebo-controlled, crossover trial of methylphenidate and placebo. Methylphenidate was an effective treatment over a 3-week period. A good response to methylphenidate was predicted by higher levels of inattentive and restless behaviour, impaired performance on tests of attention, clumsiness, younger age and by the absence of symptoms of overt emotional disorder. DSM-III and ICD-9 diagnoses of 'hyperactivity' were not good predictors. The results support the validity of a construct of hyperactivity in describing childhood psychopathology, but emphasize the need for a refinement of diagnostic criteria.

Attention↗
PubMed1986

Agreement between teachers' ratings and observations of hyperactivity, inattentiveness, and defiance.

The relationship of directly observed classroom behavior and teacher ratings on questionnaires with a judgemental (Conners Teacher Rating Scale) or operational format was examined for 33 boys aged 6 years 5 months to 7 years 7 months. Results showed a high degree of association between observed and rated behavior. This association did not vary with the format of the rating scales but did vary with the nature of the behavior being rated. Defiance was more reliably rated than hyperactivity or inattentiveness. Several behaviors exerted a halo effect on ratings of hyperactivity, inattentiveness, and behavior problems. In particular, defiance toward a teacher increased the likelihood that a child would be rated as hyperactive or inattentive regardless of his observed level of activity or attentiveness. These results support the validity of behavior rating scales as screening measures for hyperactivity, inattentiveness, and defiance and indicate that a child's defiance and disobedience are significant causes of misclassification.

Attention↗
PubMed1986

Conduct disorder and hyperactivity: I. Separation of hyperactivity and antisocial conduct in British child psychiatric patients.

The distinction between hyperactivity and conduct disorder was explored in a mixed group of 64 children referred to psychiatric clinics because of antisocial or disruptive behaviour. A semi-structured interview measure (the Parental Account of Children's Symptoms, PACS) proved to have adequate inter-rater reliability, internal consistency and factorial validity. The PACS scales of defiance and hyperactivity, and similar subscales from Conners' Teacher Rating Scale, were tested against laboratory and clinical measures of activity, attention, cognitive performance, psychosocial background and family relationships. The hyperactivity (but not the defiance) scales were associated with greater activity, younger age, poorer cognitive performance and abnormalities on a developmental neurological examination. The defiance (but not the hyperactivity) scales were associated with impairment of family relationships and adverse social factors. It was concluded that a dimension of inattentive, restless activity should be separated from one of antisocial, defiant conduct in children with psychiatric disorder.

Antisocial Personality Disorder↗
PubMed1986

Conduct disorder and hyperactivity: II. A cluster analytic approach to the identification of a behavioural syndrome.

Sixty boys, aged from 6 to 10 years, were studied after their referral to psychiatric clinics for antisocial or disruptive behaviour. Their scores on reliable measures of hyperactivity, defiant behaviour, emotional disorder and attention deficit were taken for the home, school and clinic settings; and subjected to two techniques of cluster analysis. Both gave a similar set of clusters, one of which had high scores on all measures of hyperactivity and attention deficit. Membership of this cluster was associated with a lower IQ, a younger age of problem onset and referral, an abnormal neurological examination, a history of developmental delay, smaller family size, poor peer relationships and a high rate of accidental injuries; and it predicted a good response to stimulant medication in a controlled trial. Other research on the classification of hyperactivity is discussed, and proposals are made for the criteria of a rather narrow definition of 'hyperkinetic conduct disorder'.

Antisocial Personality Disorder↗