As ADHD prevalence climbs, pediatricians play key role in diagnosis, medication guidance

Health care professionals should talk to parents so medications are resumed in a safe and timely manner.

From the late 1980s to the early 2000s, the rate of diagnosis of attention deficit/hyperactivity disorder (ADHD) soared 500%, and about 5% to 10% of all U.S. children between the ages of 6 and 18 have been diagnosed with ADHD.

There are myriad ideas as to why the prevalence of children with ADHD has increased — some studies have suggested diet, other studies suggest overdiagnosis of the condition. Whatever the reasons, the start of the school year presents an important opportunity for pediatricians to counsel patients about their medication.

Christopher Kratochvil, MD, Professor of Psychiatry and Pediatrics, University of Nebraska Medical Center, said that too often, “summer vacation” is synonomous with “medication holiday,” and these patients that take breaks from their medication need guidance on restarting for the school year. Stimulant medications have a rapid onset of action and can be restarted with relative ease, while the only two non-stimulant FDA-approved medications, atomoxetine (Strattera) and guanfacine (Intuniv), should be reinitiated several weeks prior to the start of the school year to achieve maximal effectiveness.

Medication overview

Short-acting stimulants are safe and highly effective, but may suffer from compliance issues due to the need for repeated dosing throughout the day, according to a review of ADHD pharmacotherapies published by Kratochvil and colleagues in the March 2009 issue of the Journal of the American Academy of Child and Adolescent Psychiatry. This can be addressed, to a significant degree, with sustained-release preparations.

“For most children, the first drug of choice is going to be a stimulant, either amphetamine or methylphenidate,” Mark Wolraich, MD, who is a professor of pediatrics at the University of Oklahoma Health Sciences Center, told Infectious Diseases in Children. “They have the strongest evidence. There have been more than 300 well-controlled studies and around 50 years of clinical experience with them, so we really know the demonstrated effects and side effects for those medications.”

Growth should be monitored in children taking stimulants, as some studies have shown a “temporary modest slowing in growth rate,” Kratochvil wrote in his pharmacotherapy review. Many parents who halt their child’s medication during the summer are hoping to initiate a growth spurt, Wolraich said.

Diet and ADHD

Despite decades of research into diet and ADHD, there is very little conclusive evidence of any relationship between how a child eats and how he or she behaves, according to Wolraich.

He pointed to a series of challenge studies conducted around the philosophies of Ben Feingold, MD, an allergist who proposed that food additives, preservatives and salicylate-containing products were major culprits in causing ADHD symptoms.

The challenge studies, which put children on restrictive diets and then challenged them by having them consume foods and beverages with the offending ingredients, “were inconclusive,” Wolriach said. “At best there was a small percentage that had a change in behavior with a challenge with a particular dye or additive. There was clearly not a consistent pattern in the studies as to whether most children were affected by it.”

Sugar, long believed to be a cause of hyperactive behavior, has not been conclusively linked to an increase in ADHD symptoms. Wolraich and colleagues conducted a double-blind, controlled trial in healthy preschoolers and elementary school-age children whose parents thought they responded adversely to sugar. They found that none of sweeteners used—either sucrose, aspartame or saccharin—had any measurable effect on the behavior and cognition. The following year, Wolraich performed a meta-analysis of the 23 studies and found that “sugar did not affect the behavior or cognitive performance of children.” A study by Hoover and Milich, in which all children were given placebo but parents of half the children were told there children were ingesting sugar, found that mothers who believed their children ingested sugar rated them significantly worse and were more likely than control mothers to maintain physical closeness, criticize, look at and talk to their children.

Likewise, there is little conclusive evidence on the effects of food additives and colorants on behavior in children with ADHD. Though research in this area has been conducted since the 1970s, “many of the studies are small or or not well constructed, and there is no consensus about how such additives might contribute to ADHD symptoms in children,” according to the June 2009 edition of the Harvard Mental Health Letter.

Recently, researchers in Britain conducted a randomized, double-blind, placebo-controlled study to examine the effects of six artificial food colorings and sodium benzoate, a preservative, on hyperactivity in 153 preschoolers. The children were from the general population and did not necessarily have ADHD, though hyperactivity was assessed in questionnaires. They found a small but significant increase in hyperactivity when children were consuming artificial colors, but when calculating “effect size,” they estimated that additives might only account for 10% of behavioral differences between children with and without ADHD.

Similarly, a Harvard meta-analysis of 15 trials concluded that removing artificial colorants from the diet of children with ADHD would be about one-third to one-half as effective as treatment with Ritalin.

But “so far, the results of additive-free diets are not all that convincing,” Wolraich said. “No diet has demonstrated the efficacy in rigorous studies that would meet the FDA requirements, or had more extensive 1-to-2-year observational studies to examine side effects and sustained efficacy.”

ADHD and age

While data are conflicting regarding food changes and ADHD, one study published last month suggested that inappropriate diagnosis may also be a contributor to the increasing rates of people with ADHD.

A recently published study by University of Notre Dame economist William Evans and colleagues at the University of Minnesota and North Carolina State University suggests that, at least in part, the epidemic may be driven by misdiagnosis. The economists reach that conclusion based on statistical analyses of data on ADHD diagnosis, medication treatment and the age of those diagnosed relative to peers enrolled in school.

The researchers noted that children who were “older for their grade” were less frequently diagnosed and treated for ADHD than classmates born just before the cutoff and, therefore, young for their grade.

Evans and his colleagues conclude in their study, published recently in the Journal of Health Economics, that some children may be mistakenly diagnosed with ADHD because they exhibit more immature behavior than older classmates.

According to the economists’ analysis, approximately 1.1 million children may have received an inappropriate diagnosis and more than 800,000 received stimulant medication due only to relative maturity.

Evans and colleagues noted in their study that diagnosing ADHD is a challenge, and the researchers called on physicians to consider factoring in school age when considering an ADHD diagnosis. – by Andy Moskowitz

References

• Pelham WE. J Consult Clin Psychol. 1990 Feb;58(1):130-3.
• Arnold LE. Arch Gen Psychiatry. 1997;54(9):865-70.
• Wolraich ML. N Engl J Med. 1994;330(5):301-7.
• Wolraich ML. JAMA. 1995;274(20):1617-21.
• Hoover DW. J Abnorm Child Psychol. 1994;22(4):501-15.
• McCann D. Lancet. 2007;370(9598):1560-7.
• Schab DW. J Dev Behav Pediatr. 2004;423-34.
• Daughton JM. J Am Acad Child Adolesc Psychiatry. 2009;240-8.