Stimulant-related state-dependent learning in hyperactive children

Methylphenidate induces state-dependency of social recognition learning: Central components

Methylphenidate (MPH) is a widely prescribed drug for the treatment of attention-deficit hyperactivity disorder. Findings in the literature suggest that the effects of MPH on memory may result from increased extracellular levels of norepinephrine (NE) and dopamine (DA). Here, we report that the systemic administration of MPH before the acquisition phase in a social discrimination task impaired the retrieval of the social recognition memory (SRM), but made it state-dependent: another administration of MPH before the retention test recovered the SRM. We observed that the induction of state dependency by MPH relies on the ventromedial prefrontal cortex (vmPFC), but not on the CA1 region of the hippocampus (CA1). Also, the inhibitors of NE and DA, nisoxetine and GBR12909, respectively, restored the SRM when infused into the vmPFC. Only the GBR12909 was able to restore the SRM in the CA1, whereas nisoxetine could not restore and even caused an impairment on memory retrieval when infused alone before the retention test. The data suggest that the state-dependence of SRM induced by MPH depends on an influence of both catecholamines on the vmPFC, while NE inhibits the retrieval of SRM on the hippocampus.

Attention-Deficit Hyperactivity Disorder

Attention-deficit hyperactivity disorder (ADHD) is the most common of the childhood psychiatric disorders, with a prevalence rate of up to 20%, and is probably genetically transmitted. ADHD is characterized by impulsive behavior, hyperactivity, and decreased attention span. It is often extremely disruptive to the afflicted individuals social interactions and school performance. Therapeutic approaches to ADHD should be multimodal, including medications, family, and educational therapies. The pathophysiology of ADHD is not yet fully understood. Catecholoamines are believed to play a significant role with serotonin in an adjunctive role. Pathophysiological theories are supported by useful drug therapies that are known to affect dopamine and norepinephrine metabolism. Stimulants remain the drugs of choice, with methylphenidate most commonly used. Dextroamphetamine and pemoline are also effective. The rational use of these drugs is discussed. Antidepressants are second-line drug therapies; their usefulness is most apparent in patients who have high levels of anxiety and/or depression. Other potentially useful medications, including clonidine and the antipsychotics, are discussed. Adult populations can also express ADHD; treatment is similar to that used in children. Overall, ADHD is an important illness with significant morbidity. Pharmacotherapy is highly effective for its treatment and forms the cornerstone of therapy. This review of ADHD seeks to promote a greater understanding of this disorder and its appropriate drug therapy.

Cocaine induces state-dependent learning of sexual conditioning in male Japanese quail

State dependent learning effects have been widely studied in a variety of drugs of abuse. However, they have yet to be studied in relation to sexual motivation. The current study investigated state-dependent learning effects of cocaine in male Japanese quail (Coturnix japonica) using a sexual conditioning paradigm. Cocaine-induced state-dependent learning effects were investigated using a 2×2 factorial design with training state as one factor and test state as the other factor. During a 14-day training phase, male quail were injected once daily with 10mg/kg cocaine or saline and then placed in a test chamber after 15min. In the test chamber, sexual conditioning trials consisted of presentation of a light conditioned stimulus (CS) followed by sexual reinforcement. During the state dependent test, half of the birds received a shift in drug state from training to testing (Coc→Sal or Sal→Coc) while the other half remained in the same drug state (Coc→Coc or Sal→Sal). Results showed that male quail that were trained and tested in the same state (Coc→Coc or Sal→Sal) showed greater sexual conditioning than male quail that were trained and tested in different states (Sal→Coc) except when cocaine was administered chronically prior to the test (Coc→Sal). For the latter condition, sexual conditioning persisted from cocaine training to the saline test. The findings suggest that state dependent effects may alter sexual motivation and that repeated exposure to cocaine during sexual activity may increase sexual motivation which, in turn, may lead to high risk sexual activities. An alternative explanation for the findings is also discussed.

Amphetamine fails to alter cued recollection of emotional images: study of encoding, retrieval, and state-dependency

Stimulant drugs facilitate both encoding and retrieval of salient information in laboratory animals, but less is known about their effects on memory for emotionally salient visual images in humans. The current study investigated dextroamphetamine (AMP) effects on memory for emotional pictures in healthy humans, by administering the drug only at encoding, only at retrieval, or at both encoding and retrieval. During the encoding session, all participants viewed standardized positive, neutral, and negative pictures from the International Affective Picture System (IAPS). 48 hours later they attended a retrieval session testing their cued recollection of these stimuli. Participants were randomly assigned to one of four conditions (N = 20 each): condition AP (20 mg AMP at encoding and placebo (PL) at retrieval); condition PA (PL at encoding and AMP at retrieval); condition AA (AMP at encoding and retrieval); or condition PP (PL at encoding and retrieval). Amphetamine produced its expected effects on physiological and subjective measures, and negative pictures were recollected more frequently than neutral pictures. However, contrary to hypotheses, AMP did not affect recollection for positive, negative, or neutral stimuli, whether it was administered at encoding, retrieval, or at both encoding and retrieval. Moreover, recollection accuracy was not state-dependent. Considered in light of other recent drug studies in humans, this study highlights the sensitivity of drug effects to memory testing conditions and suggests future strategies for translating preclinical findings to human behavioral laboratories.

The effects of methylphenidate on cognitive performance of healthy male rats

WE AIMED TO INVESTIGATE THE EFFECTS OF METHYLPHENIDATE (MPH) IN HEALTHY RATS ON TWO DISTINCT RADIAL MAZE TASKS WHICH RELY ON BRAIN STRUCTURES AND NEUROTRANSMITTERS KNOWN TO BE AFFECTED BY MPH: the Random Foraging Non-Delay Task (RFNDT) and the Delayed Spatial Win Shift Task (DSWT). Hooded Lister rats were trained to complete either the RFNDT or the DSWT having received oral treatment of either a vehicle or MPH (3.0 mg/kg and 5.0 mg/kg for RFNDT, 3.0 mg/kg for DSWT). We found no effect of MPH on the RFNDT relative to the control group. However, those treated with 5.0 mg/kg MPH did take significantly longer to reach criterion performance than those treated with the 3.0 mg/kg MPH, suggesting some doses of MPH can have detrimental effects. For the DSWT, if MPH was present in both phases, performance did not differ from when it was absent in both phases. However, when present in only one phase there was an increase in errors made, although this only reached significance for when MPH was present only in the test-phase. These data suggest that MPH may have detrimental effects on task performance and can result in state-dependent effects in healthy individuals.

Safety and efficacy of donepezil in children and adolescents with autism: neuropsychological measures

OBJECTIVE

There has been recent interest in the use of cognitive enhancing drugs, such as cholinesterase inhibitors, as a possible treatment for executive functioning (EF) deficits in autism spectrum disorder (ASD). The goal of this study was to assess the tolerability, safety, and efficacy of donepezil on EF in a sample of children and adolescents with ASD.

METHOD

Thirty-four children and adolescents with ASD (age range 8-17 years; IQ >75) were enrolled in a 10-week, double-blind, placebo-controlled trial of donepezil (doses of 5 and 10 mg), followed by a 10-week open label trial for placebo nonresponders.

RESULTS

The effect of donepezil treatment on EF was examined. Despite improvement on a number of EF measures, no statistically significant between-group differences were found (with gains observed for both the placebo and donepezil groups).

CONCLUSIONS

The results suggest that short-term treatment with donepezil may have limited impact on cognitive functioning in ASD. Future controlled trials may need to consider a longer treatment period to detect significant gains on EF measures.

Treatment of a 7-Year-Old Hyperactive Boy with Educational Problems

A 7-year-old hyperactive boy with multiple problems was treated using a combination of interventions, applied sequentially over 14 months. The first phase of treatment was participation in a drug trial (placebo, then drug) and this was followed by cognitive-behavioural training designed to teach strategies with which to approach academic work. Teacher and parent behaviour ratings showed improvement over the drug trial period and educational gains were made during the cognitive-behavioural training, both in the area specifically taught and other academic subjects. The problems choosing appropriate targets and of disentangling the effects of different treatment components are discussed.

The laboratory school protocol: its origin, use, and new applications

OBJECTIVE

ADHD is the most common childhood psychiatric disorder, with impairments seen in home and academic settings. To investigate such impairments in a school-like setting, the laboratory school protocol (LSP) was developed at the University of California, Irvine.

METHOD

This model provides a rigorously controlled environment to examine pharmacodynamic and pharmacokinetic aspects of responses to treatment. A key principle of this methodology is to exercise tight control of the timing and context of measurements by establishing a cycle of activities repeated across each study day. In addition, the LSP approach has been extended to both younger and older populations than the typically studied school-aged group. This extension requires corresponding modifications in measures to characterize drug efficacy and to allow evaluation of ADHD symptoms in a highly standardized setting.

RESULTS

This article provides guidelines for employing the LSP for the assessment of medication effects for both preschool and adolescent/adult populations.

CONCLUSION

The LSP can be modified to form either an Adult Workplace Environment or a Preschool Assessment Laboratory.

Effect of methylphenidate on time perception in children with attention-deficit/hyperactivity disorder

The effects of methylphenidate (MPH) on performance of a time-production task were studied in 17 children with attention-deficit/hyperactivity disorder who participated in 1 test session on and 1 off MPH. Participants held a response lever down for at least 10 but no longer than 14 s. Administration of MPH had no effect on the number of correct responses or on the mean duration of lever holds. MPH administration significantly decreased timing response variability, increased holds of 10- to 11-s duration, and decreased lever holds of extremely short durations. These results indicate that administration of MPH resulted in more precise timing performance without changing the mean duration of lever holds, suggesting an enhancement in working memory.

Pharmacokinetic and pharmacodynamic properties of stimulants: implications for the design of new treatments for ADHD

In the USA, the stimulant drug methylphenidate (MPH) is used to treat a large number (2 million or more per year) of children with Attention Deficit Hyperactivity Disorder (ADHD). Although the US FDA approved MPH in the 1960s, the pharmacokinetic (PK) properties of serum concentrations of MPH in children with ADHD were not described until the 1980s, and then in only a few cases. Recently, information from drug development programs have increased our knowledge about the serum PK and some pharmacodynamic (PD) characteristics of MPH in ADHD children, and studies based on positron emission tomograpy (PET) in adult volunteers have provided new knowledge about the PK properties of MPH at the primary site of action in the brain. We will review these two topics and use this new information to evaluate the mechanisms of action of MPH.

The imbalanced brain: from normal behavior to schizophrenia

An outstanding problem in psychiatry concerns how to link discoveries about the pharmacological, neurophysiological, and neuroanatomical substrates of mental disorders to the abnormal behaviors that they control. A related problem concerns how to understand abnormal behaviors on a continuum with normal behaviors. During the past few decades, neural models have been developed of how normal cognitive and emotional processes learn from the environment, focus attention and act upon motivationally important events, and cope with unexpected events. When arousal or volitional signals in these models are suitably altered, they give rise to symptoms that strikingly resemble negative and positive symptoms of schizophrenia, including flat affect, impoverishment of will, attentional problems, loss of a theory of mind, thought derailment, hallucinations, and delusions. This article models how emotional centers of the brain, such as the amygdala, interact with sensory and prefrontal cortices (notably ventral, or orbital, prefrontal cortex) to generate affective states, attend to motivationally salient sensory events, and elicit motivated behaviors. Closing this feedback loop between cognitive and emotional centers is predicted to generate a cognitive-emotional resonance that can support conscious awareness. When such emotional centers become depressed, negative symptoms of schizophrenia emerge in the model. Such emotional centers are modeled as opponent affective processes, such as fear and relief, whose response amplitude and sensitivity are calibrated by an arousal level and chemical transmitters that slowly inactivate, or habituate, in an activity-dependent way. These opponent processes exhibit an Inverted-U, whereby behavior becomes depressed if the arousal level is chosen too large or too small. The negative symptoms are owing to the way in which the depressed opponent process interacts with other circuits throughout the brain.

Naltrexone in young autistic children: replication study and learning measures

OBJECTIVE

This study expanded upon previous work on naltrexone efficacy and safety in young autistic children and assessed performance on learning measures.

METHOD

Eleven children with autistic disorder, aged 3.0 to 8.3 years, were studied in home, school, and outpatient laboratory, bringing to 24 the combined study sample. Naltrexone, 1.0 mg/kg, was given daily in a randomized, double-blind, crossover design. Dependent measures were parent and teacher Clinical Global Impressions (CGI) and Naltrexone Side Effects Rating Scale (SE), Conners Parent Impulsivity/Hyperactivity Factor, Teacher Hyperactivity Factor, laboratory CGI, and analysis of videotaped behavior. Learning measures were the Early Intervention Developmental Profile-Language and paired-associate learning.

RESULTS

Comparisons between naltrexone and baseline, but not naltrexone and placebo, on parent and teacher ratings showed statistical significance. Three of 11 subjects improved in two or more settings. Side effects were mild. Administering naltrexone was a challenge. The combined study sample showed improvement on all parent measures and on Teacher CGI and SE-Restlessness compared with baseline and placebo. Eleven of the 24 children improved in two or more settings. Scores on learning measures did not change across conditions.

CONCLUSIONS

Naltrexone was associated with modest improvement of behavior in 11 of 24 children, but learning did not improve.

Mood-state-dependent retrieval: the effects of induced mood on memory reconsidered

Analysis of studies investigating mood-state-dependent retrieval identifies methodological problems that may have contributed to the controversy surrounding the reliability of the effect-in particular, the possible confounding of encoding and retrieval in previous studies. Five experiments are reported investigating the effects of mood on learning and recall. Mood-state-dependent retrieval was observed in Experiment 1a (using Velten's Mood Induction Procedure); Experiment 1b (using a music MIP); and Experiment lc (using Velten's MIP at encoding and a music MIP at retrieval). Subjects who learned and recalled in different moods had significantly greater decrements in recall than did subjects in the same moods. Experiments 2 and 3 investigated the effect of observable retrieval cues on mood-state-dependent retrieval. In Experiment 2, the presence of observable retrieval cues at recall overrode state-dependent retrieval. In Experiment 3, by manipulating the presence or absence of observable cues at recall, both the occurrence and the erasure of the mood-state dependency was demonstrated. Mood state during learning and cued recall was also shown to affect performance in a third session under conditions of free recall.

NIMH collaborative multisite multimodal treatment study of children with ADHD: I. Background and rationale

OBJECTIVE

The National Institute of Mental Health's recently initiated 5-year, multisite, multimodal treatment study of children with attention-deficit hyperactivity disorder (MTA) is the first major clinical trial in its history focused on a childhood mental disorder. This article reviews the major scientific and clinical bases for initiating the MTA.

METHOD

A selective review of the literature is presented in the service of describing the estimated prevalence of ADHD among children and adolescents, its core clinical features, evidence concerning psychopharmacological and psychosocial treatment effects, and related research issues and trends leading to the development of the MTA.

RESULTS

Despite decades of treatment research and clinical practice, there is an insufficient basis for answering the following manifold question: under what circumstances and with what child characteristics (comorbid conditions, gender, family history, home environment, age, nutritional/metabolic status, etc.) do which treatments or combinations of treatment (stimulants, behavior therapy, parent training, school-based intervention) have what impacts (improvement, stasis, deterioration) on what domains of child functioning (cognitive, academic, behavioral, neurophysiological, neuropsychological, peer relations, family relations), for how long (short versus long term), to what extent (effect sizes, normal versus pathological range), and why (processes underlying change)?

CONCLUSIONS

The important scientific, clinical, and public health issues nested within this manifold question provide both the impetus and scaffolding for the MTA.

Phenytoin and phenobarbital: a comparison of their state-dependent effects

Two commonly used antiepileptic drugs, phenytoin sodium and phenobarbital sodium, were investigated for state-dependency effects at different doses. Male Wistar strain rats trained to a criterion in an inhibitory avoidance task and a food-motivated T-maze task under varying drug and nondrug states were subjected to retention tests 24 and 48 h, respectively, following acquisition. The treatment instituted at the time of retrieval was either the same as, or different from, that used during training. The results indicated that phenytoin produced state-dependency effects at test doses of 20, 40, and 60 mg/kg in the avoidance task and at test dose of 20 mg/kg in the T-maze task experiments. These state-specific effects were comparable to those of phenobarbital sodium (5 and 10 mg/kg). The reinstitution of the drug state in an additional test session produced approximately equal and significant recovery of conditioned responses in the T-maze paradigm both in phenytoin and phenobarbital groups. These results demonstrate, for the first time, the ability of phenytoin to produce state-dependency effects in a pattern similar to that observed with a widely studied compound such as phenobarbital. Overall, the data provide no support for the view that the degree of discriminability of a drug is an indicator of potential state-dependency effects and is restricted only to the dosage high enough to produce noticeable intoxication.

The utility of curriculum-based measurement for evaluating the effects of methylphenidate on academic performance

Two case studies were conducted to investigate the utility of curriculum-based measurement of math and reading for evaluating the effects of methylphenidate on the academic performance of 2 students diagnosed with attention deficit hyperactivity disorder. Following baseline measurement, double-blind placebo-controlled procedures were employed to evaluate each student's response to three levels (5 mg, 10 mg, and 15 mg) of the medication. Results of the first study suggest that the curriculum-based measures were sensitive indicators of the student's response to medication. This finding was replicated in the second study. In the second study, when the student's follow-up dose of medication was based on trial-phase data, follow-up performance was improved compared to baseline performance. These case studies suggest that further research is warranted on the utility of curriculum-based measurements for monitoring and evaluating stimulant medication interventions with children with this disorder.

Effects of a few food diet in attention deficit disorder

Seventy-eight children, referred to a diet clinic because of hyperactive behaviour, were placed on a 'few foods' elimination diet. Fifty nine improved in behaviour during this open trial. For 19 of these children it was possible to disguise foods or additives, or both, that reliably provoked behavioural problems by mixing them with other tolerated foods and to test their effect in a placebo controlled double blind challenge protocol. The results of a crossover trial on these 19 children showed a significant effect for the provoking foods to worsen ratings of behaviour and to impair psychological test performance. This study shows that observations of change in behaviour associated with diet made by parents and other people with a role in the child's care can be reproduced using double blind methodology and objective assessments. Clinicians should give weight to the accounts of parents and consider this treatment in selected children with a suggestive medical history.

Pharmacodynamics of pemoline in attention deficit disorder with hyperactivity

The onset, duration, and offset of pemoline action to improve cognitive performance is examined intensively in 25 prepubescent males suffering from attention-deficit disorder with hyperactivity (ADDH). The purpose was to characterize the pharmacodynamics of pemoline in ADDH patients through correlation of plasma pemoline concentration with psychometric measures of memory search efficiency and paired-associates learning, with the physiological effect of pemoline on dopaminergic transmission concurrently measured by analysis of plasma prolactin response. The effect of pemoline on neuroprocessing is apparent within the first 2 hours after administration with an inverse relationship between plasma pemoline and prolactin concentration present at hour one only (r = 0.84; p = 0.005). Pemoline therapy for 3 weeks does not significantly affect area under the curve for pemoline or prolactin nor did the effect on memory search efficiency decrease, suggesting no apparent tolerance.

Effect of naltrexone upon self-injurious behavior, learning and activity: a case study

Naltrexone significantly attenuated self-injurious behavior in a 20-year-old mildly retarded autistic male patient. The patient was videotaped daily and behavior was evaluated with a time-sampling procedure. Behavioral ratings of SIB frequency, SIB severity, and activity were collected automatically with a computerized system. Learning and memory were tested on a weekly basis with a modification of a paired associate learning test (PALT). Treatment with naltrexone resulted in (a) attenuation of SIB in the unstructured setting and (b) improvements in learning and memory without influencing activity levels.

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.

Effects of caffeine on classroom behavior, sustained attention, and a memory task in preschool children

The effects of caffeine on the behavior of young children is an important issue, as children in our society consume considerable amounts of caffeine, primarily in soft drinks. This study investigated the effects of normative amounts of caffeine on the behavior of 6 normal children in a kindergarten setting. Using a reversal design, counterbalanced for order of conditions, children's behavior was examined during a baseline condition, a caffeinated beverage condition, and a noncaffeinated beverage condition. Measures included direct observation of off-task and gross motor activity, actometer readings of movement, a Continuous Performance Test, a Paired Associates Learning Test, and teacher ratings of classroom behavior. Results suggest that caffeine exerts only small and inconsistent effects on the classroom behavior of kindergarten children. These results cast doubt on the importance of caffeine as a variable controlling the classroom behavior of normal kindergartners.

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'.

Short term effects of methylphenidate on the cognitive, learning and academic performance of children with attention deficit disorder in the laboratory and the classroom

Sixteen children meeting diagnostic criteria for Attention Deficit Disorder with Hyperactivity (ADD-H) were tested on methylphenidate (0.3 mg/kg) and placebo on cognitive, learning, academic and behavioral measures in a double-blind study. Assessments were carried out in the laboratory and in the children's regular classrooms. Results indicate methylphenidate-induced improvements on a majority of the measures. Drug-induced changes reflected increased output, accuracy and efficiency and improved learning acquisition. There was also evidence of increased effort and self-correcting behaviours. It is argued that reviewers have underestimated the potential of stimulants to improve the performance of ADD-H children on academic, learning and cognitive tasks.

Methylphenidate in hyperactive children: differential effects of dose on academic, learning, and social behavior

Methylphenidate (Ritalin) has been shown to have differential effects on hyperactive children's behavior as a function of dose level. In the present investigation, a triple-blind, placebo-control, within-subject (crossover) experimental design was employed in which 12 hyperactive boys between 6 and 10 years received three different dosages of methylphenidate (5, 10, and 15 mg) in a randomly assigned sequence. Dosage effects were assessed on clinic-(PAL--Paired Associates Learning test) and school-(percent on task, teacher ratings, work completion rates, and accuracy) related behaviors. For 10 of the children, classified as responders to medication by the PAL using the criteria of Swanson, Kinsbourne, and colleagues, a series of ANCOVAs with repeated measures showed significant dosage effects on teacher ratings (p less than .01), percent on task (p less than .01), academic accuracy (p less than .05), and assignment completion rates (p less than .05). PAL performance was also significantly enhanced (p less than .01) after optimal dose levels were considered. Subsequent trend analysis showed a significant positive linear relationship between dose and each of the dependent variables. A comparison of fixed-dose and miligram-per-kilogram plots showed that children's performance across the different dosages were clearly individualistic and task-specific, even when similar body weights were compared. The implications of using clinic-based testing to determine optimal medication responsivity were discussed.

Effects of sucrose ingestion on the behavior of hyperactive boys

A challenge design was used in two separate studies to investigate the effects of sucrose ingestion on the behavior and learning of hyperactive boys. In both studies, 16 boys were admitted to a clinical research center for 3 successive days, on each of which they were given a sucrose-free diet. On day 1, baseline levels on the learning tasks were established; on days 2 and 3 a challenge drink of either sucrose 1.75 gm/kg or a placebo (aspartame in equivalent sweetness) was presented, in a counterbalanced order. In the first study the challenge drink was administered 1 hour after lunch; in the second study it was given in the morning after an overnight fast. On days 2 and 3 of both studies, 37 behavioral (playroom observation and examiner ratings) and cognitive (learning and memory tasks) measures were collected, starting 1/2 hour after ingestion of the drink. The results of both studies revealed no differences between the boys' performance on the two challenge days. These findings undermine the hypothesis that sucrose plays a major role in accounting for the inappropriate behavior of hyperactive boys.

Amnesia for criminal offences

Nearly 10% of a sample of men charged with a variety of offences claimed amnesia for their offence. The amnesia occurred only among those who had committed violence and was most frequent following homicide. All the amnesics had a psychiatric disorder, four having a primary depressive illness and the remainder being almost equally divided between schizophrenia and alcohol abuse. None of the amnesias had any legal implications. The circumstances of the offences suggested a variety of mechanisms to account for the amnesia, including repression, dissociation and alcoholic black-outs. Psychological defence mechanisms were probably of some importance, even when alcohol was an important factor.

Effects of two doses of methylphenidate on cross-situational and borderline hyperactive children's evoked potentials

This study involved 27 children displaying cross-situational hyperactivity and 14 youngsters with borderline hyperactivity. For all patients, evoked potentials were recorded after receiving 0 (placebo), 0.3 and 0.6 mg/kg methylphenidate. Under each pharmacologic condition, subjects were administered: a photic stimulation procedure; two versions of the Continuous Performance Test (CPT), which varied in difficulty level; and a discrimination ('oddball') test. Under photic stimulation, methylphenidate reduced the impact of increasing brightness levels on the rates of amplitude increment and latency decrease in the P208 component of the visual evoked response. These results are similar to those obtained by Buchsbaum and Wender (1973) for hyperactive patients with a positive clinical response to amphetamine. In CPT and the discrimination test, the two active dosages of methylphenidate brought about a comparable reduction of placebo levels of errors and reaction time. Analogously, in both versions of CPT, the two active dosages resulted in comparable increases in the amplitude of two components of the late positive complex (LPC; P510 and P740). P510 was identified as a classical P300. In the discrimination test, the effect of the stimulant on the response evoked by the visual non-target was to increase the amplitude of a component (P463) previously identified as P300. These pharmacologic results were nearly identical for borderline and cross-situational patients. In general, the results confirmed previous observations that methylphenidate improves hyperactive children's performance and increases the amplitude of their LPC. Further, these findings support previous observations that hyperactive patients' cognitive processing is optimized by a dosage of 0.3 mg/kg methylphenidate. Finally, the similarity between findings for cross-situational and borderline hyperactive patients is consistent with other evidence that stimulant effects are not limited to classically hyperactive children.

Drug treatment of hyperactivity in children

Recently-developed quantitative reviewing procedures were applied to 61 selected studies in order to explore the efficacy of pharmacological management for children identified as hyperactive. Analysis of effect-size information derived from the studies revealed that the average child receiving drug treatment was less hyperactive than 88.5 per cent of the control children. 30 per cent of this effect could be attributed to placebo phenomenon. The analysis also indicated that drug therapy had the most pronounced effect on dependent variables consisting of standardized or informal measures of behaviour and the least effect on measures of IQ and academic achievement. The advantages of quantitative reviewing methodology for adding clarity and consensus to complex bodies of literature are demonstrated and discussed.

Effects of stimulant drugs on academic performance in hyperactive and learning disabled children

The effect of stimulant drugs upon academic performance in hyperactive (HA), learning disabled (LD), and hyperactive-learning disabled (HA-LD) children has been a matter of controversy for over a decade. Research on this topic is reviewed with attention to specific academic skills, methodological issues, relative efficacy of drug, educational, and multimodal interventions, and clinical implications. It is concluded that while stimulants may increase academic productivity, (a) the effect on standardized achievement test scores is not particularly robust; (b) individual reaction is quite variable; (c) the clinical implications for adult outcome appears to be minimal; and (d) some behavioral interventions are clearly superior. However, the number of pertinent subject, task, treatment, and setting variables is so great that a definitive answer with regard to the relationship between pharmacotherapy and academic performance is anything but close at hand.

Children with reading disorders--II. Effects of methylphenidate in combination with reading remediation

Sixty-six children received individual reading instruction for 18 weeks, in combination with methylphenidate (mean daily dose 44.2 mg/day) or a placebo. Assignment to medication was random and double blind. Children were re-evaluated at the end of treatment, and two and eight months later. Only occasional and weak methylphenidate effects were obtained on measures of reading performance. Highly significant improvement in some tests of mathematics was found. No treatment differences occurred at follow-up. The results do not support the hypothesis that the enhancement of attention with stimulant treatment facilitates the acquisition of reading skills in children with pure reading disorders.