June 17, 2008 11:43 am Published by Francisco Monegro, Ph.D., M.D.
From the perspective of the science of behavior, functional analysis has been one of the most used methodologies to assess severe problematic behaviors in autistic individuals. Functional analysis is a synthesis of the “cause-and-effect relationships” expressed in quantitative terms that identify the conditions that determine the occurrence or non-occurrence of a problematic behavior (Skinner, 2005; Iwata, Dorsey, Slifer, Bauman, & Richman, 1982/1994; Van Camp, et. al. 2000). However, functional analysis does not always give accurate information about the function of the behavior, especially for severe self-injurious behavior, property destruction, and aggression.
Dr. Henry Roane in his presentation at the 2008 Applied Behavior Analysis International Annual Convention (ABAI) in Chicago pointed out that for some autistic individuals with severe and complicated problematic behaviors, functional analysis does not easily identify the reinforcers that maintain the behavior. Dr. Roane found that “the outcome data presented by previous researchers suggest that 4-15% of functional analysis results yield undifferentiated outcomes.” Occasionally, the maladaptive behavior is maintained by idiosyncratic stimuli, which are unusual environmental stimuli such as an odor, color, noise, texture, or a person, a variety of repetitive behaviors among other conditions, that are not normally the focus of functional analysis or are often assumed to be maintained by automatic reinforcement. Normally, functional analysis identifies such causes as attention seeking, escape-avoidance from demands; obtainment of tangible items or edibles, and control conditions (e.g. lack of structure/boredom, limited repertoires or lack of sensory input) (Iwata et al. (1982/1994).
Descriptive observations may yield information that lead to the identification of idiosyncratic reinforcers that sustain the maladaptive behaviors. For instance, severe self-injurious behaviors, property destruction and aggressive behaviors may occur when repetitive behavior is interrupted or prevented, when staff may allow resumption of repetitive behavior contingent upon destructive behaviors or is reinforced by access to repetitive behavior. Dr. Roane reviewed several cases where a destructive behavior was maintained by access to items, such as when a consumer gains access to a wrist band that triggers a hand biting response.
Dr. Roane illustrated in his ABAI presentation in Chicago that Behavior Analysts face a number of challenges when using common functional analysis. One of the challenges is understanding that complex self-injurious behaviors or severe aggressive behaviors are not always maintained by the type of reinforcements that behavioral analysts generally look for. Behavior Analyst needs to identify the idiosyncratic stimuli before the implementation of functional analysis (Van Camp, et. al. 2000; Carr et. al. 1997). Anytime that the Behavior Analyst finds a discrepancy between the interview information and the functional analysis data, he or she should suspect that the severe problematic behavior is maintained by idiosyncratic stimulus. One issue Behavioral Analysts would need to discuss is how to develop a standard methodology to identify these kinds of stimuli. Without the identification of idiosyncratic stimuli that maintain severe problematic behaviors, the Behavior Analysts may generate an unclear functional analysis and a behavioral intervention that is less effective (Carr et. al. 1997).
June 4, 2008 4:44 am Published by Francisco Monegro, Ph.D., M.D.
Currently, scientists have developed different research approaches in associated areas and disciplines of the core symptom domains of autism spectrum disorder.
According to Dr. Daly, genetics in autism spectrum disorder are basically puzzles. Dr. Weiss (NEJM, 2008), in a study that involved 751 multiplex families withautism, concluded that heritability in autism seems to be idiopathic in about 90% [unknown causes] and about 10% of cases can be explained by genetic syndromes and chromosomal abnormalities. Dr. Arking and colleagues (AJHG, 2008) identified a common polymorphism in contactin-associated protein-like 2 (CNTNAP2), a member of the Neurexin super-family, that is, children with autism tended to have inherited the thymine rather than adenine variant of CNTNAP2.
Drs. Scherer and Szatmari from the Autism Genome Project (Nature Genetics, 2007) discovered a previously unidentified region of chromosome 11 the Neurexin 1 (NRXN1) gene, which is associated with the release of the neurotransmitter glutamate and plays an important role in early brain development.
The Autism Genetic Resource Exchange (AGRE), a collaborative gene bank created and managed by the Cure Autism Now Foundation, has been facilitating more rapid progress in the identification of the genetic variations of autism spectrum disorders by making this information available to the scientific community.
The M.I.N.D. institute has been a pioneer in autism research in neurodevelopment. Dr. Amaral and colleagues from the M.I.N.D. Institute are interested in a neurodevelopment genomics program with the goal of identify “biomarkers.” Dr. Amaral stated, “Our goal is to develop a diagnostic test within five years to accurately identify those newborns who are likely to develop autism. Identification of susceptible children is the first step to prevention of full-blown autism, and if we can prevent even 10 percent of the new cases of autism that will be a major accomplishment.” In a study conducted by Grether et al., (2001), researches revealed elevated levels of neuropeptides and neurotropins for children who have autism and are mentally retarded. Another area of study at the M.I.N.D Institute is the effect of the maternal immune system and environmental insults during pregnancy to understand the gene-environment interactions and their role in the development of autism.
Some patterns of neuropathologies have been examined and correlated with autism spectrum disorder such as greater brain size and weight; abnormalities in the limbic system (amygdala, thalamus, hippocampus), basal ganglia, medial temporal lobe, vestibular system, fewer Purkinje cells in the cerebellum; age-dependent cellular abnormalities in cerebellar nuclei, and cortical dysgenesis (Chugan; Kemper & Bauman, 1998). In addition, Dr. Chugani studies the role of the Serotonin in autism. According to several studies elevated blood serotonin is present in approximately 30%-50% of autistic subjects and their families, and tryptophan depletion exacerbates autism symptoms. Dr. Chugani suggests that although autism spectrum disorder shares multiple causes there is the possibility of a common neuro-chemical mechanistic feature (MP, 2002).
For example, by using MRI scans and longitudinal studies of head circumference, Dr. Piven found indications that autism onset seems to occur in the early postnatal period, around 12 months of age. He also discovered that toddlers with autism had generalized enlargement of gray and white matter cerebral volumes, but not cerebellar volumes. In addition, head circumference appeared normal at birth in autistic individual, but the rate of growth began to increase significantly more than in the control children at around 12 months of age (Piven, 2005).
Tuberous sclerosis and epilepsy are two conditions that may relate with mutations in two genes that regulate cell growth, TSC1 and TSC2. Some studies show evidences for the role of cerebellar abnormalities in autistic children with tuberous sclerosis may be lesions in the cerebellum. Changes in the pathway of Tryptophan’s metabolism in the brain may be associated with tuberous sclerosis complex, epilepsy, and autism. Neurotoxity is another area that is gaining attention from researchers. Understanding how neurochemistry is altered in autism may help for new strategies for pharmacological intervention.
Other line of neurobiological research has implicated the dopamine, serotonin and recently glutamate systems in the pathogenesis of autism (McDougle et. al. 1998). The Research Units on Pediatric Psychopharmacology (RUPP) Autism Network is testing new treatments for children and adolescents with autism and related disorders (Scahill, 2007-NYAS) Dr. Scahill quoted a line he attributed to Donald Cohen: “When there is no cure, there are 100 treatments.”
Currently, drugs used for autism come from many different classes of compounds such as Clonidine, Propranolol, Depakote, D-Cycloserine, Oxytocin, Memantine, Minocycline, Riluzole and parasite treatment (Trichuris Suis Ova [TSO]. Some studies show results that are insignificant, that used small sample sizes and targeted unclear symptoms. For instance, Dr. Scahill points out that randomized controlled trials with Naltrexone targeted increased communication and utterance, instead of self-injurious behaviors. Several studies with Selective Serotonin Reuptake Inhibitors (SSRIs) have been insufficient in term of the design features and targeted autistic population. According to Dr. Scahill, another important challenge and research agenda is to combine medication with behavioral interventions.
Since Autism Spectrum Disorder (ASD) is not a single condition, it makes very difficult to segregate individuals into homogeneous subgroups that can be studied. While the research is growing, scientists need to redefine autism phenotypes, genotypes and the neurobiology and neuropathology of autism spectrum disorder (Schmitz & Rezaie, 2008; Gilliam, 2007-NYAS).