Screening for cognitive and social–emotional problems in individuals with PKU: Tools for use in the metabolic clinic

Abstract

Cognitive deficits, learning difficulties, and emotional problems occur at significantly higher rates in individuals with phenylketonuria (PKU) than in the general population. The relationship between elevated blood phenylalanine (Phe) levels and the severity of these problems often remain unrecognized. Children and adults with PKU require ongoing screening so that referrals to psychologists or psychiatrists familiar with metabolic disorders can be made when necessary for in-depth evaluation and treatment. To identify screening instruments that can be used by non-psychologists as well as psychologists, a group of 10 psychologists and a psychiatrist in the United States with expertise in neuropsychological assessment and PKU proposed a Uniform Assessment Method for PKU. Questionnaires were selected that reliably detect problems in adaptive behavior, executive function, and emotional well-being, representing the most vulnerable areas for individuals with PKU. These questionnaires are appropriate for individuals from infancy through adulthood, may be administered in less than 1 h, have computerized scoring accessibility, have no practice effects, and are available in Spanish and English. In addition to assessing function at a single point in time, the screening measures may be administered at each clinic visit to assess changes in function related to metabolic status or treatment (e.g., Phe-restricted diet, food supplements). The following questionnaires comprise the Uniform Assessment Method for PKU: for 0–2 years, Adaptive Behavior Assessment System – Second Edition (ABAS-II); for 2–17 years, Behavior Rating Inventory of Executive Function (BRIEF) and Behavior Assessment System for Children – Second Edition (BASC-II); and for adults, BRIEF, Beck Anxiety Inventory (BAI), and Beck Depression Inventory – Second Edition (BDI-II). In addition to long-term monitoring of outcomes in PKU, this uniform screening approach facilitates PKU research, as data may be pooled across multiple clinics using a consistent battery of assessment measures.