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.

Prospective follow-up studies found no chromosomal mutagenicity of methylphenidate therapy in ADHD affected children.

Walitza S, Kämpf K, Oli RG, Warnke A, Gerlach M, Stopper H

Department of Child and Adolescent Psychiatry, University of Zurich, Zurich, Switzerland.

Five to ten percent of all children suffer from attention-deficit/hyperactivity disorder (ADHD), which is often treated with the central nervous stimulant methylphenidate (MPH). In 2005 controversy arose due to a report of enhanced cytogenetic effects in 12 children after 3 months of MPH treatment. Since then, several prospective studies have been performed and published, which are summarized here. A table comparing the micronucleus frequencies, a marker investigated in all of these studies, is presented. An induction of cytogenetic effects by MPH was only reported in one, the 2005 study by El-Zein et al., while all other studies, with now altogether 110 MPH-exposed individuals, showed no elevation. To address the question of long-term use of MPH, we published the data of 30 chronically treated children and also saw no difference compared to untreated children. Here, we report as new follow-up data that an additional 12 months time point in a small group of 12 children who had begun MPH therapy within our published study also did not reveal elevated cytogenetic damage. Furthermore, a previously unpublished analysis of urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG; a non-invasive biomarker for DNA-base oxidation and its repair) in 11 children before and after 3 months of MPH exposure yielded no significant difference. Since gene mutations may not necessarily manifest as chromosomal aberrations, micronuclei or SCEs, we discuss the available data from animal models, which also do not reveal a mutagenic potential of MPH. Although the only two available epidemiological studies do not report elevated risk for MPH exposure, the results are not conclusive yet, and further monitoring of exposed populations is suggested.

Published 15 February 2010 in Toxicol Lett, 193(1): 4-8.
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Articles on Ritalin published 9 February 2010:

Flow cytometric detection of Pig-A mutant red blood cells using an erythroid-specific antibody: application of the method for evaluating the in vivo genotoxicity of methylphenidate in adolescent rats.   Environ Mol Mutagen, 51(2): 138-45.

A modified flow cytometry assay for Pig-A mutant rat red blood cells (RBCs) was developed using an antibody that positively identifies rat RBCs (monoclonal antibody HIS49). The assay was used in conjunction with a flow cytometric micronucleus (MN) assay to evaluate gene mutation and clastogenicity/aneugenicity in adolescent male and female rats treated with methylphenidate hydrochloride (MPH). Sprague-Dawley rats were treated orally with 3 mg/kg MPH (70/sex) or water (40/sex) 3 x /day on ... [Abstract] [Full-text]

Articles on Ritalin published 11 January 2010:

No increases in biomarkers of genetic damage or pathological changes in heart and brain tissues in male rats administered methylphenidate hydrochloride (Ritalin) for 28 days.   Environ Mol Mutagen, 51(1): 80-8.

Following a 2005 report of chromosomal damage in children with attention deficit/hyperactivity disorder (ADHD) who were treated with the commonly prescribed medication methylphenidate (MPH), numerous studies have been conducted to clarify the risk for MPH-induced genetic damage. Although most of these studies reported no changes in genetic damage endpoints associated with exposure to MPH, one recent study (Andreazza et al. [2007]: Prog Neuropsychopharmacol Biol Psychiatry 31:1282-1288) reported ... [Abstract] [Full-text]

Articles on Ritalin published 6 November 2009:

Descending glutamatergic pathways of PFC are involved in acute and chronic action of methylphenidate.   Brain Res, 1301: 68-79.

Progressive augmentation of behavioral response following repeated psychostimulant administrations is known as behavioral sensitization, and is an indicator of a drug's liability for abuse. It is known that methylphenidate (MPD) (also known as Ritalin), a drug used to treat attention-deficit hyperactivity disorder (ADHD), induces sensitization in animals following repeated injections. It was recently reported that bilateral electric (non-specific) lesion of prefrontal cortex (PFC) prevented MPD ... [Abstract] [Full-text]

Articles on Ritalin published 14 September 2009:

Methylphenidate for giggle incontinence.   J Urol, 182(4): 2028-32.

PURPOSE: Giggle incontinence or enuresis risoria is a socially embarrassing problem characterized by involuntary and complete bladder emptying in response to laughter. To our knowledge the cause of giggle incontinence is unknown, although a functional relationship to cataplexy was suggested. We retrospectively examined the effectiveness of methylphenidate for giggle incontinence in children. MATERIALS AND METHODS: We retrospectively reviewed the charts of patients referred to a pediatric ... [Abstract] [Full-text]

Articles on Ritalin published 19 August 2009:

Attention deficit hyperactivity disorder erroneously diagnosed and treated as bipolar disorder.   J Atten Disord, 13(2): 197-8.

OBJECTIVE: There is a dearth of literature on patients erroneously diagnosed and treated for bipolar disorder. METHOD: The authors report a case of an adult with attention deficit hyperactivity disorder erroneously diagnosed and treated for bipolar disorder for 6 years. At that point, methylphenidate was initiated. The patient was judged to be a good treatment responder with improvements noted in the clinical global impressions severity scale. It was seen that the improvement was maintained at ... [Abstract] [Full-text]

Articles on Ritalin published 17 August 2009:

Limits of meta-analysis: methylphenidate in the treatment of adult attention-deficit hyperactivity disorder.   J Psychopharmacol, 23(7): 733-44.

Guidelines for the treatment of attention-deficit hyperactivity disorder (ADHD) in adults advocate methylphenidate as first-line treatment. The aim of this study was to review the effectiveness of methylphenidate treatment of adult ADHD and to examine the influence of methods on meta-analytic results. Electronic databases were searched to identify clinical trials comparing methylphenidate with placebo in the treatment of adult ADHD. Studies were summarised with meta-analytic methods. Subgroup ... [Abstract] [Full-text]

Articles on Ritalin published 13 August 2009:

OROS methylphenidate for the treatment of adults with attention-deficit/hyperactivity disorder.   Expert Rev Neurother, 9(8): 1121-31.

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common behavioral disorders in childhood. It continues into adulthood in up to 65% of patients. Methylphenidate (MPH) is one of the most commonly used pharmacological treatments for ADHD. The osmotic-release oral system (OROS) formulation of MPH is an extended-release pharmaceutical form that delivers MPH in a controlled manner over a 12-h period, allowing management of symptoms for a full day. OROS-MPH has many advantages over ... [Abstract] [Full-text]

Articles on Ritalin published 11 August 2009:

Methylphenidate induction of complex visual hallucinations.   J Child Neurol, 24(8): 1005-7.

A 15-year-old boy with attention-deficit hyperactivity disorder (ADHD) presented with complex visual hallucinations of rats running around and touching and smelling him soon after receiving a first low dose of methylphenidate. The hallucinations resolved upon discontinuation of the drug. Reintroduction of the drug 7 years later at an even lower dose had the same effect. Other cases of vivid complex hallucinations of living creatures associated with methylphenidate have been reported in the ... [Abstract] [Full-text]

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