A new study reviews existing research on the link between various psychotic symptoms such as hallucinations, problems with concentration or anxiety, and the drug methylphenidate (Concerta, Ritalin) — researchers found 1 or 2 percent of treated patients may experience such adverse effects.

Their paper is published in the Scandinavian Journal of Child and Adolescent Psychiatry and Psychology.

Methylphenidate is a stimulant drug commonly prescribed as a treatment for attention-deficit/hyperactivity disorder (ADHD) and narcolepsy. The drug increases activity in the central nervous system and is supposed to help combat fatigue, improve attention and maintain alertness. Its medical use began in the year 1960 and has continued to grow ever since, reaching global consumption of 2.4 billion doses in 2013.

Some 5.3 percent of children and adolescents around the world have ADHD; psychostimulants, including methylphenidate, are often the first-choice drug treatment.

Clinical studies have previously confirmed the safety and effectiveness of methylphenidate and shown that its long-term use can reduce abnormalities in brain structure and function usually associated with ADHD.

Currently, there is very little evidence in the literature on the association between methylphenidate treatment and psychotic symptoms in children and adolescents with attention-deficit/hyperactivity disorder (ADHD).

For the new paper, study author Erica Ramstad and others reviewed the existing evidence to determine whether methylphenidate increases the risk of psychotic symptoms in children and adolescents affected with ADHD.

The researchers reviewed a total of 10 randomized trials (1,103 participants), 17 non-randomized studies (76,237 participants) and 12 patient reports or series (18 patients). They found 873 instances of psychotic symptoms in the non-randomized studies among 55,603 participants. In the comparative cohort study (a type of observational study), methylphenidate significantly increased the risk for any psychotic disorder by 36 percent.

Although the amount and quality of existing data did not allow the researchers to draw any strong conclusions, their findings suggest that possible adverse symptoms may affect around 1.1 percent to 2.5 percent of the ADHD patients being treated with methylphenidate.

The review has significant implications for patients, physicians and caregivers who should be aware of possible adverse effects of the drug. In case psychotic symptoms develop during methylphenidate treatment, clinicians should be able to address the problem, reduce or stop stimulant medication and ensure proper treatment in its place.

ADHD is a brain disorder characterized by an ongoing pattern of inattention, hyperactivity and/or impulsivity that interferes with functioning and development. For a person to receive a diagnosis, the symptoms must be chronic or long-lasting, impair the person’s functioning, and cause the person to fall behind normal development for his or her age, according to the National Institutes of Mental Health (NIMH).

Source: Exeley Inc.