Ritalin Research Today is a free monthly online journal that collates and summarizes the latest research about Ritalin, including details on attention-deficit hyperactivity disorder, prescription, dosage, side-effects.

Methylphenidate has differential effects on blood oxygenation level-dependent signal related to cognitive subprocesses of reversal learning.

Dodds CM, Müller U, Clark L, van Loon A, Cools R, Robbins TW

Behavioral and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, United Kingdom. cd317@cam.ac.uk

Complete understanding of the neural mechanisms by which stimulants such as methylphenidate ameliorate attention deficit hyperactivity disorder is lacking. Theories of catecholamine function predict that the neural effects of stimulant drugs will vary according to task requirements. We used event-related, pharmacological functional magnetic resonance imaging to investigate the effects of 60 mg of methylphenidate, alone and in combination with 400 mg of sulpiride, on blood oxygenation level-dependent (BOLD) signal in a group of 20 healthy participants during probabilistic reversal learning, in a placebo-controlled design. In a whole-brain analysis, methylphenidate attenuated BOLD signal in the ventral striatum during response switching after negative feedback but modulated activity in the prefrontal cortex when subjects maintained their current response set. The results show that the precise neural site of modulation by methylphenidate depends on the nature of the cognitive subprocess recruited.

Published 5 June 2008 in J Neurosci, 28(23): 5976-82.
Full-text of this article is available online (may require subscription).

Articles on Ritalin published 22 May 2008:

Varying the wear time of the methylphenidate transdermal system in children with attention-deficit/hyperactivity disorder.   J Am Acad Child Adolesc Psychiatry, 47(6): 700-8.

OBJECTIVE: Children with attention-deficit/hyperactivity disorder often have varying needs for coverage of their symptoms throughout the day. The objectives of this study were to determine the efficacy, duration of action, and safety of methylphenidate transdermal system worn for variable times by children (ages 6-12) diagnosed with ADHD. METHOD: Methylphenidate dose was optimized over 5 weeks using 10-, 15-, 20-, or 30-mg patches worn for 9 hours. The efficacy of 4- and 6-hour wear times was ... [Abstract] [Full-text]

Articles on Ritalin published 2 April 2008:

Can methylphenidate reduce fall risk in community-living older adults? A double-blind, single-dose cross-over study.   J Am Geriatr Soc, 56(4): 695-700.

OBJECTIVES: To test the hypothesis that methylphenidate modifies markers of fall risk in older adults. DESIGN: Randomized, double-blind, placebo-controlled, single-dose cross-over study. SETTING: Outpatient movement disorders clinic. PARTICIPANTS: Twenty-six community-living older adults without dementia (mean age 73.8) with subjective complaints of "memory problems." INTERVENTIONS: The study examined the effects of a single dose of 20 mg of methylphenidate (MPH) on cognitive function ... [Abstract] [Full-text]

Articles on Ritalin published 26 February 2008:

Development and validation of a liquid chromatography-mass spectrometry assay for hair analysis of methylphenidate.   Forensic Sci Int, 176(1): 42-6.

Methylphenidate (MPH) is a phenethylamine derivative used in the treatment of childhood attention-deficit hyperactivity disorder. MPH is biotransformed in the body by the hydrolysis of the methyl ester linkage to its metabolite, ritalinic acid. Whereas both compounds are usually measured in plasma and urine, preliminary observations show that only the parent compound is present in hair from treated individuals. Since in children hair samples can be easily collected without the need for special ... [Abstract] [Full-text]

Articles on Ritalin published 15 January 2008:

Antidepressant treatment can normalize adult behavioral deficits induced by early-life exposure to methylphenidate.   Biol Psychiatry, 63(3): 309-16.

BACKGROUND: Methylphenidate (MPH) is prescribed for the treatment of attention-deficit/hyperactivity disorder. Exposure to MPH before adulthood causes behavioral deficits later in life, including anxiety- and depression-like behaviors and decreased responding to natural and drug rewards. We examined the ability of fluoxetine (FLX), a selective serotonin reuptake blocker, to normalize these MPH-induced behavioral deficits. METHODS: Male rats received MPH (2.0 mg/kg) or saline (VEH) during ... [Abstract] [Full-text]

Articles on Ritalin published 8 January 2008:

Functional magnetic resonance imaging of methylphenidate and placebo in attention-deficit/hyperactivity disorder during the multi-source interference task.   Arch Gen Psychiatry, 65(1): 102-14.

CONTEXT: Previous studies have reported hypofunction, structural abnormalities, and biochemical abnormalities of the dorsal anterior midcingulate cortex (daMCC) in attention-deficit/hyperactivity disorder (ADHD). Stimulant medications are effective treatments for ADHD, but their neural effects have not been fully characterized. OBJECTIVE: To determine whether the methylphenidate hydrochloride osmotic-release oral system (OROS) would increase functional magnetic resonance imaging (fMRI) ... [Abstract] [Full-text]

Articles on Ritalin published 21 December 2007:

An expert opinion on methylphenidate treatment for attention deficit hyperactivity disorder in pediatric patients with epilepsy.   Expert Opin Investig Drugs, 17(1): 77-84.

Methylphenidate (MPH) is one of the most commonly prescribed medications to treat attention deficit hyperactivity disorder (ADHD). Despite the elevated rates of ADHD in children with epilepsy, few studies have examined the use of MPH in this population. Case reports have warned about new-onset seizures in patients treated with MPH, and drug-drug interactions between MPH and antiepileptic drugs (AEDs), as well as antidepressants. However, retrospective chart reviews, open-label trials and ... [Abstract] [Full-text]

Articles on Ritalin published 11 December 2007:

Early stress and chronic methylphenidate cross-sensitize dopaminergic responses in the adolescent medial prefrontal cortex and nucleus accumbens.   J Neurochem, 103(6): 2234-44.

Methylphenidate (MP) is widely used to treat attention deficit/hyperactivity disorder in children. However, basic research has been mainly focused on MP treatment in adult, behaviorally normal rodents. Here we analyzed MP-evoked changes of dopamine (DA) release in the limbic system of juvenile rodents with hyperactive and attention deficit-like symptoms. Using dual probe in vivo microdialysis, DA levels were quantified in the medial prefrontal cortex and nucleus accumbens of juvenile and ... [Abstract] [Full-text]

Articles on Ritalin published 23 November 2007:

A phase III, double-blind, placebo-controlled prospective randomized clinical trial of d-threo-methylphenidate HCl in brain tumor patients receiving radiation therapy.   Int J Radiat Oncol Biol Phys, 69(5): 1496-501.

PURPOSE: The quality of life (QOL) and neurocognitive function of patients with brain tumors are negatively affected by the symptoms of their disease and brain radiation therapy (RT). We assessed the effect of prophylactic d-threo-methylphenidate HCl (d-MPH), a central nervous system (CNS) stimulant on QOL and cognitive function in patients undergoing RT. METHODS AND MATERIALS: Sixty-eight patients with primary or metastatic brain tumors were randomly assigned to receive d-MPH or placebo. The ... [Abstract] [Full-text]

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