Update on Autism
Update on Autism
Autism is demanding increased attention by professional and lay audiences; prevalence seems to be increasing. There are differing opinions about whether the increase is due to greater recognition and reporting, diagnostic expansion and substitution, or increasing acceptability. On the other hand, the increase may be a consequence of environmental toxins or infectious and immune vulnerability and epigenetics or perhaps a combination of social and environmental factors.
Clearly, autism has a large genetic component and multiple genes are involved in various combinations. Nevertheless, the prevalence of autism in the United States and in other countries has increased exponentially; this trend would not happen with a purely genetic disorder. Most autism researchers accept a theory of etiology that starts with a genetic neurodevelopmental vulnerability combined with an environmental stressor through such epigenetic processes as immune function.1
Increasingly, researchers and clinicians refer to autism to describe a wide variety of phenotypes that start with genes and gene expression and range through a variety of metabolic functions to symptoms that cluster diagnostically but have a great deal of individuality. Symptoms can range from mild to severe and may be associated with mental retardation; GI and neurological involvement; and behavioral, emotional, cognitive, and whole body pathology.2
Here we discuss diagnostic assessment and classification, co-occurring or comorbid psychiatric disorders and their differential diagnosis, the medical workup, and possible medical comorbidities. We also review a model for psychosocial treatment as well as psychopharmacological and alternative treatments. We conclude with a brief look at the future of research and treatment.
Diagnostic assessment and classification
The term “autism (or autistic) spectrum disorder” (ASD) is likely to be replaced with “pervasive developmental disorder” in DSM-5. ASD is a collection of neurodevelopmentally based conditions of social and communicative impairments, each with varying severity and broadness of expression.
Autism was originally described by Leo Kanner in the early 1940s and termed “early infantile autism” of unknown etiology. By the 1960s, work on high concordance of autism in monozygotic twins and lower concordance in dizygotic twins and siblings led to the present-day understanding of ASD as a developmental and neurobiological condition with heterogeneous genetic and possible epigenetic triggers.
Diagnosis of ASD remains an empirical and behavioral procedure with no clear or single biological marker or assay. This has made reliable and valid diagnosis problematic: signs of ASD selected for inclusion in DSM have had fairly high diagnostic sensitivity but often poor specificity.3-5 Symptoms of ASD overlap with those of other neurodevelopmental disorders. Accurate differential diagnosis and diagnosis of comorbid conditions in ASD are therefore difficult.
The best practice for clinical assessment of ASD involves multiple methods of measuring multiple traits (Figure). Both parents and child contribute to data collection via interview and record review. The child is also observed directly or on video in the home, at school, and in the clinic under structured and unstructured conditions.6-8 The Autism Diagnostic Interview-Revised (ADI-R) and Autism Diagnostic Observation Schedule (ADOS) are considered to be the gold standard in ASD diagnosis and are widely used in research.
Psychiatric workup and comorbidity
Because a behavior can reflect different etiologies and symptoms can overlap, other disorders need to be carefully considered. Within the differential for ASD are anxiety disorders, attention-deficit/hyperactivity disorder (ADHD), and even prodromal schizophrenia or schizoid personality disorder.
When children are anxious, particularly when they have symptoms consistent with obsessive-compulsive disorder, they can manifest an inflexibility about routines (serving to bind their anxiety) and exhibit tics or behavioral compulsions that can be mistaken for stereotypies. Likewise, it can be difficult to delineate anxiety from the overwhelming biological basis for ASD in which learning deficits lead to anxious behavior.
Children with ADHD can seem socially impaired. But rather than having a deficit in theory of mind, the ability to understand another’s perspective through one’s own similar reasoning and experience, these children miss social cues (because they do not attend to them) or behave impulsively around peers, which can result in their being ostracised. The social withdrawal associated with thought disorders can be mistaken for the impairments in social interaction characteristic of ASD.
? Signs of autism spectrum disorder (ASD) selected for inclusion in DSM have had fairly high sensitivity to the clinical diagnosis of autism, but they often show poor specificity.
? A diagnosis of autism can be made only if the child’s social interactions are not commensurate with his or her developmental level.
? Psychiatric comorbidities, such as anxiety and attention-deficit/hyperactivity disorder, and medical comorbidities, such as epilepsy, sleep disorders, and Tourette syndrome, are frequent in ASD.
? ASD is heterogeneous in expression, and treatment plans must target ASD and comorbid disorders that may require integrated yet separate treatment..
? Psychopharmacological agents can help with symptoms of ASD, such as irritability, impulsivity, and anxiety; however, they do not seem to help directly with core symptoms of social reciprocity or communication, although they may do so indirectly through improved availability for treatment.
ASD can also be misdiagnosed in children who have a language disorder.9 Communication deficits can lead to social impairment, but these are secondary to limitations in reciprocal exchanges (and resultant frustration). In addition, the classification of receptive and expressive language disorders in DSM is nosologically different from American Speech-Language-Hearing Association standards.