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PubMed1997

Effects of methylphenidate on preschool children with ADHD: cognitive and behavioral functions.

OBJECTIVE: To report on implications for methylphenidate treatment of this very young age group and the need to examine factors related to achieving compliance. METHOD: Thirty-one children with attention-deficit hyperactivity disorder (ADHD), aged 4 to 6 years, participated in a double-blind, placebo-controlled study using placebo, 0.3 mg/kg, and 0.5 mg/kg of methylphenidate twice per day. RESULTS: Improvements related to medication were obtained on cognitive tests of attention and impulsivity as well as behaviors assessed by parent rating scales. In an interactive setting with their mothers, attentional abilities and the children's ability to work more productively also showed improvement. However, no changes were obtained with respect to the children's tendency to comply with parental requests. Side effects increased slightly with the high dosage of medication but remained mild. CONCLUSION: The results suggest that methylphenidate can be used to improve the functioning of preschool-age children with ADHD, in a manner similar to their school-age counterparts.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

Differential effects of methylphenidate on attentional functions in children with attention-deficit/hyperactivity disorder.

OBJECTIVE: To examine the effects of methylphenidate on different attentional functions and behavior in children with attention-deficit/hyperactivity disorder (ADHD). METHOD: A total of 60 ADHD children aged between 8 and 12 years completed a randomized, double-blind, placebo-controlled, within-subject crossover trial with two doses of methylphenidate (0.25 and 0.5 mg/kg body weight) and placebo. A comprehensive neuropsychological test battery was applied, including tests of alertness and sustained, focused, and divided attention as well as two executive tests, the stop-signal paradigm and a visual set-shifting task. RESULTS: A linear improvement was identified for both medication conditions in the alertness and focused and sustained attention task, but no significant improvement was found for divided attention. Quadratic trends were found for both executive tasks. Responders defined by behavior ratings did not differ from nonresponders. CONCLUSIONS: Results indicate that attentional functions are influenced differentially by methylphenidate: intensity-dimension functions are best influenced by higher doses, executive functions by moderate doses, and selectivity-dimension functions by variable doses. In addition, divergent results from behavior rating scales and from attentional paradigms emphasize that clinicians have to decide what constitutes an appropriate clinical response. A more comprehensive assessment of attention may help to find an individually optimal dose for the treatment of attentional dysfunctions.

Attention↗
PubMed1982

Effect of methylphenidate on thought processing time in children.

Methylphenidate is commonly prescribed for children in order to improve attentional aspects of their behavior. However, resultant long-term academic improvement in these children is negligible. To investigate this discrepancy, a reaction time paradigm was utilized with 10 males and 2 females (mean age was 9.8 years; SD, 1.6 years) diagnosed as having an attentional deficit disorder. Using a double-blind procedure with methylphenidate and a placebo, a decrease in simple reaction time was found in the medication condition. However, no drug effect was found on decision times using a choice reaction time task. It was concluded that methylphenidate and perhaps other stimulant medications affect attentional processes in hyperactive youth but may not affect those higher cortical processes required to make long-term academic gains.

Achievement↗
PubMed1984

Effects of two doses of methylphenidate on verbal information processing in hyperactive children.

Nine hyperactive children participated in three sessions. During each they were given one of three drugs (placebo, 10 mg, or 21 mg of methylphenidate) in a double-blind crossover study. Following drug administration they were tested on three cognitive tasks. For one task, structural, acoustic, or semantic degrees of encoding of verbal information were induced. Memory for the verbal information was then tested. The 10-mg dose resulted in overall improvement of word recognition and recall. The 21-mg dose did not result in improvement. Amount of improvement was not related to degree of encoding of words. Two other tasks, learning a list of words and visual search of letters from a briefly presented display, were not affected by either the 10- or 21-mg dose. The results indicate that verbal learning can be facilitated by a low dose of methylphenidate but that the dose range may be narrow. Also, certain individuals did not respond favorably to either dose. In discussing the results, the possibility is presented that methylphenidate-induced facilitation may be restricted to certain types of learning or certain methods of assessing retrieval of information.

Attention↗
PubMed2002

Comparative efficacy of Adderall and methylphenidate in attention-deficit/hyperactivity disorder: a meta-analysis.

Because methylphenidate is currently the most widely prescribed medication for attention-deficit/ hyperactivity disorder, several studies have used it as the active comparator medication for evaluating the efficacy of a newer stimulant, Adderall. These prior studies show Adderall to be superior to placebo and suggest it is at least as effective as the standard-release form of methylphenidate and has a longer duration of action. Although these initial studies provide useful information for clinicians treating children with attention-deficit/hyperactivity disorder, they are difficult to interpret because findings vary among studies and among the different types of measures used within each study. To provide a clearer picture of what conclusions can be drawn from these studies, we performed a meta-analysis. Data from the four available studies suggest that Adderall has a small but statistically significant advantage over the standard-release form of methylphenidate. This advantage was observed for both symptom measures and global ratings but was strongest for global ratings. The effect of Adderall was significant for clinician and parent ratings but not for teacher ratings and was significant for both fixed-dose and best-dose designs.

Adolescent↗
PubMed2002

Abuse and toxicity of methylphenidate.

The therapeutic use of methylphenidate for the management of attention-deficit hyperactivity disorder in children is increasing. As therapeutic use increases, the risk increases of unintentional overdoses, medication errors, and intentional overdoses caused by abuse, misuse, or suicide gestures and attempts. Side effects during therapy, which include nervousness, headache, insomnia, anorexia, and tachycardia, increase linearly with dose. Clinical manifestations of overdoses include agitation, hallucinations, psychosis, lethargy, seizures, tachycardia, dysrhythmias, hypertension, and hyperthermia. Methylphenidate tablets can be abused orally, or they can be crushed and the powder injected or snorted. Despite its abuse potential, there is disagreement regarding the extent to which methylphenidate is being diverted from legitimate use to abuse in preteens and adolescents.

Adolescent↗
PubMed2006

Pharmacogenetics of methylphenidate response in preschoolers with ADHD.

OBJECTIVE: The authors explored genetic moderators of symptom reduction and side effects in methylphenidate-treated preschool-age children diagnosed with attention-deficit/hyperactivity disorder (ADHD). METHOD: DNA was isolated from 81 subjects in a double-blind, placebo-controlled, crossover methylphenidate titration. Parents and teachers completed ADHD symptom scales and side effect ratings for each of five randomly administered weekly conditions that included immediate-release methylphenidate 1.25, 2.5, 5.0, 7.5 mg and placebo given three times daily. Candidate genes hypothesized to influence stimulant effects or individual risks for ADHD were genotyped. RESULTS: Although the primary analysis did not indicate significant genetic effects, secondary analyses revealed associations between symptom response and variants at the dopamine receptor (DRD4) promoter (p=.05) and synaptosomal-associated protein 25 (SNAP25) allelesT1065G (p=.03) andT1069C (p=.05). SNAP25 variants were also associated with tics (p=.02), buccal-lingual movements (p=.01), and irritability (p=04). DRD4 variants were also associated with picking (p=.03). Increasing dose predicted irritability (p=.05) and social withdrawal (p=.03) with DRD4 variants. There were no significant effects for the dopamine transporter (DAT1). CONCLUSIONS: Emerging evidence suggests the potential for understanding the individual variability of response to and side effects of ADHD medications from the study of genetics, although additional research is required before these findings are proven to have clinical utility.

Attention Deficit Disorder with Hyperactivity↗
PubMed2005

A controlled trial of methylphenidate in adults with attention deficit/hyperactivity disorder and substance use disorders.

AIMS: Attention deficit/hyperactivity disorder (ADHD) is common among adult patients with substance use disorders. The benefits of treating ADHD in these patients are uncertain and the prescription of psychostimulants is disputed, because of the risk of abuse. This study examined the short-term effectiveness of methylphenidate treatment for ADHD in adults with substance use disorders. DESIGN: Double-blind, placebo-controlled, multiple cross-over (A-B-A-B design) comparative trial of methylphenidate versus placebo. SETTING: In-patient addiction treatment facility. PARTICIPANTS: Twenty-five patients with ADHD who were receiving in-patient treatment for various substance use disorders. INTERVENTION: During the course of 8 weeks, each participant completed two phases of placebo and two phases of active medication treatment, in a fixed low-dosage schedule (up to 0.6 mg/kg/day). Abstinence was maintained during the study. MEASUREMENTS: The outcome measure was ADHD symptomatology, as measured with the ADHD rating scale-IV. The results were compared using MANOVA repeated measures. FINDINGS: Nineteen of the 25 patients completed the trial. A significant reduction in ADHD symptoms was observed in the first week in both conditions. The positive response to active treatment (nine patients; 36%) was not significantly higher than that to placebo (five patients; 20%). CONCLUSIONS: In this small pilot study, the effect of low-dose methylphenidate in adult ADHD patients with concomitant substance use disorders is limited. ADHD symptoms in adults were susceptible to a distinct short-term placebo response.

Adult↗
PubMed1979

Pharmacokinetics of methylphenidate in hyperkinetic children.

1 Pharmacokinetic study has been carried out following oral administration of 10-20 mg of methylphenidate hydrochloride to four behaviorally disorders children. 2 It is indicated that the drug is metabolized to ritalinic acid with an apparent plasma half life of 2.5 h. 3 The variability in magnitude of plasma concentration seems to be due not to its metabolism to ritalinic acid but due to the variability in the apparent volume of distribution. 4 The brief half life of methylphenidate which parallels the short duration of action of methylphenidate in behaviorally disordered children may be explained in part by its low protein binding which results in high percentage of free drug being made available for metabolism to pharmacologically inactive metabolites.

Biotransformation↗
PubMed1985

Dyskinetic symptoms in profoundly retarded residents following neuroleptic withdrawal and during methylphenidate treatment.

This is a between-groups comparison of chronic drug therapy in profoundly retarded residents. One group of residents received maintenance antipsychotic medication before the study, whereas the control group had been drug-free. Both groups were assessed for dyskinetic symptoms at ten weekly intervals as dosage was phased out in the neuroleptic group. During weeks seven to nine, a double blind, placebo controlled, crossover trial of methylphenidate (Ritalin) took place. Although the original purpose of this was to determine whether methylphenidate helped to suppress chronic behaviour problems, its effects on dyskinetic symptoms were studied as well. Dyskinetic symptoms were marginally higher within the neuroleptic group but they increased strikingly over time irrespective of group membership. Drug consumption, expressed in terms of chlorpromazine equivalents and effect on the dopamine system, was found to be associated with total dyskinetic symptoms at one of two follow-up intervals. Methylphenidate caused a significant increase in dyskinesia scores but this occurred on a minority of subscales.

Adolescent↗
PubMed1991

Methylphenidate-induced changes in ADDH information processors.

In a randomized double-blind placebo-controlled crossover study, 17 hyperactives, clinically considered as drug responders, were administered a battery of information processing tasks to assess the efficacy of methylphenidate. The investigation concentrated on sustained attention, and, following a linear stage model of information processing (divided and focused attention), encoding, filtering, selective set and response organization operations. Methylphenidate did not affect short-term memory or visual retention, baseline motor speed and encoding. Methylphenidate improved vigilance aspects of sustained attention. The drug did not improve filtering but did enhance selective set (target search) operations. The decline in speed and speed variability as a result of medication could not readily be explained in terms of response organization processes. An attempt was made to unite the experimental results through the concept of signal-response frequency.

Arousal↗
PubMed1991

A divided attention analysis of the effects of methylphenidate on the arithmetic performance of children with attention-deficit hyperactivity disorder.

Thirteen boys with Attention-Deficit Hyperactivity Disorder (ADHD) completed 80 arithmetic problems presented on a computer screen by typing a two digit answer. On half the trials, a foot press was required to terminate a computer-generated tone presented 2 seconds before, 1 second before, 1 second after, and 2 seconds after arithmetic problem presentation. Compared to placebo, methylphenidate resulted in significantly faster reaction times (RTs) to tone probes and faster answers to arithmetic problems when the two tasks did not overlap in time, but not when simultaneous processing was required when the probe was presented 2 seconds after arithmetic problems. When dual processing taxed cognitive capacity, methylphenidate still improved accuracy on the primary arithmetic task relative to placebo, but at the expense of speed of performance on the secondary RT task. When ADHD children fail to allocate available resources to a primary cognitive task, treatment with methylphenidate may result in reallocation of existing cognitive capacity from a secondary task to the primary task.

Attention↗
PubMed1982

Effect of methylphenidate hydrochloride on stature of hyperactive children.

Twenty-six hyperactive children receiving methylphenidate hydrochloride, eight hyperactive non-medicated children and 25 normal children participated in a study of the effect of such medication on stature of hyperactive children. All the children were below 13 years of age and all but two were male. Predicted adult stature before methylphenidate treatment and predicted adult stature after one year, two years and three years of treatment were calculated by means of the Roche-Weiner-Thissen Adult Stature Prediction Formula. Total milligrams per day dosage, milligrams per kilogram per day dosage and duration of treatment per year were analysed in the medicated hyperactive children and their growth was compared with the other two groups. No significant differences were found for any of the above variables. This study indicates that stature suppression does not occur in male children below 13 years of age when methylphenidate is used up to 0.8mg/kg/day for one or two years and up to 0.6mg/kg/day for three years.

Attention Deficit Disorder with Hyperactivity↗
PubMed1994

Methylphenidate and ADHD: influence of age, IQ and neurodevelopmental status.

Sixty-nine children with attention deficit hyperactivity disorder (ADHD) underwent blind methylphenidate trials. 36 had ADHD alone (with or without a learning disability) and 33 had additional neurodevelopmental disorders. Of the children with ADHD alone, 88 per cent improved significantly on methylphenidate. This did not differ significantly from the 69 per cent response rate for children with ADHD and other neurodevelopmental disorders. The results confirm and add to the research literature indicating that ADHD children who are of preschool age and/or who have co-existing neurological disorders may benefit from methylphenidate.

Adolescent↗
PubMed2005

A triple mutation in the second transmembrane domain of mouse dopamine transporter markedly decreases sensitivity to cocaine and methylphenidate.

Previously, we reported that Phe105 in transmembrane domain 2 of the mouse dopamine transporter (DAT) is crucial for high-affinity cocaine binding. In the current study, we investigated whether other residues surrounding Phe105 also affect the potency of cocaine inhibition. After three rounds of sequential random mutagenesis at these residues, we found a triple mutant (L104V, F105C and A109V) of mouse DAT that retained over 50% uptake activity and was 69-fold less sensitive to cocaine inhibition when compared with the wild-type mouse DAT. The triple mutation also resulted in a 47-fold decrease in sensitivity to methylphenidate inhibition, suggesting that the binding sites for cocaine and methylphenidate may overlap. In contrast, the inhibition of dopamine uptake by amphetamine or methamphetamine was not significantly changed by the mutations, suggesting that the binding sites for the amphetamines differ from those for cocaine and methylphenidate. Such functional but cocaine-insensitive DAT mutants can be used to generate a knock-in mouse line to study the role of DAT in cocaine addiction.

Amino Acid Substitution↗
PubMed1996

The use of methylphenidate in the treatment of refractory neurocardiogenic syncope.

Recurrent neurocardiogenically mediated episodes of hypotension and bradycardia are a common cause of recurrent syncope that can be identified by head upright tilt table testing. While the use of beta-blockers, theophylline, fludrocortisone, disopyramide, and serotonin re-uptake inhibitors can be helpful in preventing further episodes, some patients are unresponsive to or poorly tolerant of these agents. We investigated the use of the central nervous system stimulant and peripheral vasoconstrictor methylphenidate in preventing both tilt induced and spontaneous neurocardiogenic syncope. Seven patients (all women, mean age 31 +/- 15 years) with recurrent syncope and positive head upright tilt induced hypotension/bradycardia (refractory to normal therapy) were placed on methylphenidate 10 mg orally three times per day. Six of the seven patients became both tilt negative and clinically asymptomatic over a 7-month follow-up period. We conclude that methylphenidate may be an effective therapy in patients with recurrent neurocardiogenic syncope refractory to other forms of therapy.

Administration, Oral↗
PubMed2006

Dopamine transporter density and behavioral response to methylphenidate in a hyperlocomotor rat model.

Rats exposed prenatally to 5-bromo-2'-deoxyuridine (BrdU-rats) display hyperlocomotive activity, making them a possibly useful animal model for the study of attention deficit hyperactivity disorder (ADHD). Using this model, we investigated dopamine transporter (DAT) density and behavioral outcomes in BrdU-rats, some of which were also administered methylphenidate, a psychostimulant that is widely used for the treatment of ADHD. Pregnant rats were exposed to BrdU from gestational day 9 through 15. In male offspring, DAT densities in different regions of the striatum were quantified at three weeks of age. At seven weeks of age, locomotor, rearing and grooming behaviors were evaluated in an open-field setting, with or without methylphenidate treatment (1 mg/kg or 4 mg/kg). The results revealed no significant changes in striatal DAT densities in BrdU-rats compared with controls. Extreme hyperlocomotion of BrdU-rats was detected in the open-field environment, an effect that was exacerbated following treatment with the lower and higher dose of methylphenidate. Such increase in locomotor activity was observed only with the higher dose in control animals. In summary, degeneration of dopaminergic neurons in the terminal field was not detected in juvenile BrdU-rats, although adult animals displayed hyperactive behavior in a mildly stressful environment as well as hypersensitivity to a psychostimulant that facilitates dopaminergic neurotransmission.

Animals↗
PubMed1977

Biochemical differentiation of amphetamine vs methylphenidate and nomifensine in rats.

Amphetamine-like stimulants were divided into two groups, one in which the stereotyped behaviour was not antagonized by reserpine [(+)-amphetamine, (-)-amphetamine, methamphetamine, phenmetrazine and phenethylamine] and another group in which the behavioural effects were blocked by reserpine (methylphenidate, nomifensine, pipradrol and amfonelic acid (NCA; Win 25978)). Both groups increased homovanillic acid (HVA) in whole brain 2 h after administration. The 'methylphenidate group' also increased brain 3,4-dihydroxyphenylacetic acid (DOPAC) in naive rats; whereas the '(+)-amphetamine group' decreased DOPAC in naive rats, as well as in reserpinized rats, alpha-methyl-p-tyrosine-treated rats and after acute hemisection. The reserpine antagonism of the 'methylphenidate group'-induced stereotyped behaviour was partially reversed by type A monoamine oxidase inhibition. The '(+)-amphetamine group'-induced stereotyped behaviour was not blocked by short time pretreatment with alpha-methyltyrosine, only by longer pretreatment intervals. The mechanisms by which the two groups are differentiated biochemically is discussed with special attention to possible intra-neuronal inhibition of dopamine oxidation by the '(+)-amphetamine group'.

3,4-Dihydroxyphenylacetic Acid↗