Aggression, nonadherence, stereotypies, property destruction, and self-injury are challenging behaviors commonly associated with ASDs. These problems can initially be screened for with a standard Likert scale, such as the Behavior Problems Inventory.13 This measure has good psychometrics and can help pinpoint specific challenging behaviors. A positive finding for challenging behaviors is followed by a functional assessment. Clinicians continue to debate whether challenging behaviors are behavioral equivalents of symptoms of psychopathology in the developmentally disabled population. However, the best evidence at present suggests that they are not. Nonetheless, in rare instances, challenging behaviors may be linked to psychopathology or to a developmental disability.
The functional assessment helps the clinician determine whether medication is appropriate. The Questions About Behavior Function (QABF) is a 25-item test designed for this purpose and can be completed in about 5 minutes.14 These potential causes of the challenging behavior are evaluated:
• The need for attention
• An attempt to escape from a task or environment
• Receipt of a tangible reward
• Physical illness or pain
An escape function may suggest the need to develop more rewarding or enriched environments. Pain may result in a conventional medical treatment (eg, head-banging because of an earache). The failure to identify 1 of these 4 underlying causes enhances the likelihood but does not confirm that the challenging behaviors are associated with physiological factors that are in turn associated with ASDs, comorbid psychopathology, or intellectual disability.
Intellectual disability and ASDs may co-occur in up to 3 of 4 affected children. While each disorder offers special challenges to the clinician, establishing the coexistence of these 2 conditions is important. Accurate diagnosis and treatment also depend on establishing the severity of intellectual disability. IQ is a particularly significant factor in poorer treatment outcomes and limits the types of psychological interventions that are appropriate. Inattention and lack of motivation to perform on cognitive tasks—which are common in children with ASDs—can result in marked underestimates of cognitive abilities. Therefore, ensuring good on-task behavior and motivation for individualized testing is essential. If this set of conditions is not possible, secondary measures of IQ—such as the Bailey Scales of Infant Development or the Vineland Social Maturity Scale—are advisable.
Concomitant psychiatric conditions occur in persons with ASDs. The type of ASD influences rates of specific psychiatric conditions. Rett syndrome and disintegrative childhood disorder are both rare forms of ASD, and little to nothing is known about coexisting psychiatric conditions.
In addition to type of ASD, intelligence and age are major moderating variables. For IQ, individuals can be grouped into HFA and Asperger syndrome, or autism and PDD-NOS where intellectual disability is present. Age often plays a role in comorbid conditions; for example, depression is more common in adolescents and adults than in young children. Notable psychiatric conditions that co-occur with ASDs are depression, anxiety, psychosis, bipolar disorder, ADHD, phobias, and OCD.6,7,15
To date, the ASD-Comorbid scale and the Psychopathology in Autism Checklist (PAC) have been developed to assess comorbid psychopathology in persons with ASDs. (We anticipate a good deal more activity in the near future.) The ASD-Comorbid scale has an adult version (intellectual disability only) and a child and toddler version (BISCUIT-2) . The adult version includes factors for anxiety/repetitive behavior, conduct problems, irritability/behavioral excesses, ADHD, and depression. The child version has factors on tantrum behavior, repetitive behavior, depression, social avoidant behavior, under- and over-eating, and conduct.2,16
The scales were developed using symptoms that typically characterize psychopathology in people with ASDs, including depression, phobia, OCD, eating disorders, conduct disorder, tic disorder, and ADHD. Cri-teria from DSM-IV-TR and ICD-10 were used in addition to symptom descriptions in the literature and related scales (such as the Diagnostic Assessment for the Severely Handicapped–II [DASH-II]). Endorsement of multiple symptoms on one of the factors may indicate comorbid psychopathology with ASDs. For example, endorsement of items such as crying, tearful or weepy, and low energy or fatigue may point to comorbid depression with ASDs.
The PAC was developed in Norway.6 It measures psychosis, depression, anxiety, and OCD. It contains 30 items that represent symptoms indicative of a major psychiatric disorder, based on DSM-IV and ICD-10 criteria, that do not overlap with core ASD symptoms (ie, hallucinations, rapid mood fluctuations, and weight change). For example, while lack of social interaction may be a symptom of both depression and autism, other symptoms of depression such as fatigue, weight change, and sad affect are not considered core symptoms of autism. By assessing the presence of these criteria, clinicians can discriminate between ASD symptoms and symptoms of psychiatric disorders.