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Summary of a presentation by Dr. Kevin Antshel, Children’s Hospital-Boston and Harvard Medical School
There have been no research studies indicating an increased risk or prevalence of Attention Deficit Hyperactivity Disorder (ADHD) in PKU. However, there has been much speculation in the medical literature as well as anecdotal reports that ADHD may be present at a rate above what is expected in the general population. I highlighted three papers that deal with PKU in the reference list that I distributed at the Ohio conference. All report neuropsychological profiles consistent with ADHD in some children and adolescents with PKU. These include deficits in sustained attention. Such deficits are certainly not enough to warrant a diagnosis of ADHD although they are often part of a larger, more complex clinical picture that also can involve executive dysfunction problems (for example, problem-solving).
Higher blood phe levels have been implicated in the development of such problems in children with PKU. It seems reasonable to postulate that poor or erratic metabolic control might result in symptoms of ADHD in some children. However, it is critical to remember that PKU and ADHD, even though they may share some features in common (especially in cases of poor metabolic control in PKU), are not the same clinical condition.
There is certainly research that does not delineate a neuropsychological profile consistent with ADHD in PKU populations. Clearly, attention deficit problems are not an inevitable consequence of having PKU.
Since there is a great deal of interest these days about ADHD, my talk in Ohio was an attempt to increase the general knowledge base about ADHD. Approximately one child in every U.S. classroom has been formally diagnosed with the disorder (it is much more common in boys than girls). This represents 3 to 5 % of all school-age children. ADHD is the most common childhood-onset neurodevelopmental disorder, yet the underlying cause is still unknown.
Diagnostic Criteria
ADHD is characterized by a persistent pattern of inattention and/or hyperactivity-impulsivity that is displayed more frequently and more severely than is typically seen in children at a similar developmental level. Hyperactive-impulsive or inattentive symptoms that cause impairment must be present before age 7, and be present in at least two settings (for example, at home and at school). There must be clear evidence of interference with developmentally appropriate social or academic functioning. This disturbance cannot be primarily attributable to a pervasive developmental disorder, nor be better accounted for by another disorder (for example, depression) Finally, symptoms must be present for at least six months.
In order to receive a diagnosis of ADHD, children or adolescents also must exhibit at least six symptoms of either inattention (ADHD-Inattentive subtype) or hyper-activity/impulsivity (ADHD-Hyperactive/Impulsive subtype). Or, if the child meets criteria for both, a diagnosis of ADHD-Combined type is more appropriate. This latter type represents 50-60% of all ADHD. The current diagnostic criteria are listed in the table above. Arriving at a diagnosis of ADHD is a multifaceted endeavor that can be complicated by many factors.
Evaluation and Treatment
A comprehensive diagnostic evaluation is critical to have prior to considering various treatment options. Typically evaluations include the following: (a) a detailed family and developmental history, (b) a detailed medical history and medical evaluation to rule-out medical causes for symptoms, (c) parent report such as checklists, (d) classroom observations including teacher ratings, and (e) a comprehensive neuropsychological evaluation. In short, there is no single test for ADHD and a multifaceted evaluation is critical for making an accurate diagnosis as well as ensuring effective treatment.
Comparing various treatments for ADHD is complicated because of the variability of children and adolescents with the disorder, the inconsistency of treatment effects on different aspects of functioning, and the complexity of the child’s family, school, and peer environments. Still, it does appear that a combination of both medication and “psychosocial” treatment approaches is most effective in treating ADHD.
Medication treatments for ADHD continue to receive considerable public attention, largely due to the increase in the use of medications such as Ritalin. The controversy over medication use relates more to diagnostic issues and not to effectiveness of the treatment. Psychostimulants like Ritalin are generally considered to be safe and effective for treating ADHD symptoms. A common fear of parents is that placing their child on a psychostimulant will increase the likelihood that he or she will eventually turn to substance abuse. Presently, no such association is thought to exist. Some researchers and clinicians argue that adolescents with ADHD who were not treated with stimulants were more likely to have substance abuse problems. The most common reason for this finding is that treated children and adolescents are more likely to remain in school and not become involved in a deviant peer group.
In addition to the psychopharmacological treatments, psychosocial interventions are also important to include. Family therapy, behavioral management training (for example, point systems or “time-out”), and social skill training for the child or adolescent are critical to include. Controlled studies have not proved the effectiveness of mineral or amino acid supplements, megavitamins, chelating agents, allergy treatments, biofeedback, sensorimotor integration, or perceptual motor training.
Conclusions
ADHD has a long and extensive history spanning a number of professional disciplines. Despite extensive research on both diagnosis and treatment, the condition continues to be controversial, and the lack of definitive diagnostic criteria and the non-specific nature of treatments have made it difficult to resolve these concerns. This is certainly an area that deserves well-designed, controlled studies to determine if the rates of ADHD in PKU exceed those found in the general population. Results from such studies might provide important information about PKU as well as about ADHD.