Targeted treatments in autism and fragile X syndrome

Autism is a neurodevelopmental disorder consisting of a constellation of symptoms that sometimes occur as part of a complex disorder characterized by impairments in social interaction, communication and behavioral domains. It is a highly disabling disorder and there is a need for treatment targeting the core symptoms. Although autism is accepted as highly heritable, there is no genetic cure at this time. Autism is shown to be linked to several genes and is a feature of some complex genetic disorders, including fragile X syndrome (FXS), fragile X premutation involvement, tuberous sclerosis and Rett syndrome. The term autism spectrum disorders (ASDs) covers autism, Asperger syndrome and pervasive developmental disorders (PDD-NOS) and the etiologies are heterogeneous. In recent years, targeted treatments have been developed for several disorders that have a known specific genetic cause leading to autism. Since there are significant molecular and neurobiological overlaps among disorders, targeted treatments developed for a specific disorder may be helpful in ASD of unknown etiology. Examples of this are two drug classes developed to treat FXS, Arbaclofen, a GABA_B agonist, and mGluR5 antagonists, and both may be helpful in autism without FXS. The mGluR5 antagonists are also likely to have a benefit in the aging problems of fragile X premutation carriers, the fragile X-associated tremor ataxia syndrome (FXTAS) and the Parkinsonism that can occur in aging patients with fragile X syndrome. Targeted treatments in FXS which has a well known genetic etiology may lead to new targeted treatments in autism.     

Association of fragile X syndrome with autism

The fragile X syndrome has been associated with autism. Blood samples from 37 autistic children and a control group were negative for fragile X chromosome. Large numbers of nonrandom autosomal lesions were observed in both the autistic and control groups.     

Behavioral observations concerning differential diagnosis between the Rett syndrome and autism

The behavior of girls with the Rett syndrome was compared to that of patients with infantile autism (Kanner syndrome) and with autism associated with infantile organic brain damage. Visual, acoustic, tactile and gustatory stimuli, and social contact were used. Motor stereotypes and disturbances were recorded and the mental development was categorized. Behavioral traits were classified into 4 groups: Behavior observed only in the Rett syndrome (at least optionally), Behavior observed in each case of the Rett syndrome (at most optionally in the autistic syndrome), Behavior observed only in the autistic syndrome (at least optionally), Behavior observed in each case of the autistic syndrome (at most optionally in the Rett syndrome). These traits were adequate criteria for differential diagnosis. It was concluded that the Rett syndrome is characterized by definite signs of dementia with almost overall developmental retardation and that it does not show several attributes regularly found in autistic children. A neuropsychological theory was proposed to explain the coming about of specific autistic behavior.     

Aripiprazole in autism spectrum disorders and fragile X syndrome

Autism spectrum disorders (ASDs) are childhood onset developmental disorders characterized by impairment of social skills and repetitive behavior, and also for classic autistic disorder, a significant impairment of communication. In addition to these core symptom domains, persons with ASDs frequently exhibit interfering behavioral symptoms, including irritability marked by aggression, self-injurious behavior, and severe tantrums. Aripiprazole is an atypical or newer generation antipsychotic with a unique mechanism of action impacting dopaminergic and serotonergic neurotransmission. The drug has been found efficacious for several indications, including most recently for use targeting irritability associated with autistic disorder in youth. Fragile X syndrome is the most common inherited cause of developmental disability and the most common known single gene cause of ASDs. As in idiopathic ASDs, irritable behavior is often exhibited by persons with fragile X syndrome. However, research to date in this disorder has not focused on this target symptom cluster. An initial pilot study has begun to assess the impact of aripiprazole on irritability in youth with fragile X syndrome.     

Behavioral phenotype of fragile X syndrome in adolescence and adulthood

The present study explored the behavioral profile of individuals with fragile X syndrome during adolescence and adulthood. Individuals with both fragile X syndrome and autism (n = 30) were compared with (a) individuals diagnosed with fragile X syndrome (but not autism; n = 106) and (b) individuals diagnosed with autism (but not fragile X syndrome; n = 135) on measures of autism symptoms, adaptive functioning, behavior problems, and psychological symptoms. Results indicated that individuals dually diagnosed with fragile X syndrome and autism displayed greater communication and social reciprocity impairments than individuals with fragile X syndrome only. Individuals in the dually diagnosed group also exhibited higher levels of repetitive and challenging behaviors than either comparison group, suggesting a unique profile of vulnerability for those diagnosed with both fragile X syndrome and autism.     

Behavioral style of young boys with fragile X syndrome

To study the behavioral style or temperament of 45 boys, aged 47 to 88 months, with full-mutation fragile X syndrome (FXS), 102 parent ratings on the Behavioral Style Questionnaire (McDevitt and Carey 1978) were recorded. These ratings were analysed with a variety of statistical techniques. Considerable variability was evident in temperament profiles; consequently, a characteristic profile was not identified for FXS. Boys with FXS differed significantly from the reference sample on five of nine temperament dimensions. They were more active and less intense, approachable, adaptable, and persistent. No significant differences were found in distractibility, rhythmicity, mood, or sensory threshold. Only 16 of the 45 boys in the sample could be classified as easy, difficult, or slow to warm up. There was no link between severity of developmental disability and temperament ratings. This supports the theory that intelligence and temperament are separate constructs. Scores on temperament dimensions were stable over time. Our results suggest that many of the behaviors observed in boys with FXS may be related to temperament. Consequently, parent counseling and environmental modifications should be considered as first line treatment. The question of whether the behavior problems observed in boys with FXS are innate or whether they result from poorness of fit between child and environment is an important issue that needs further study.     

Distinguishing features of autism in boys with fragile X syndrome

Background Males with fragile X syndrome and autism (FXS/autism) represent a distinct subgroup of males with FXS at risk for markedly poorer outcomes. Early identification and intervention can improve outcomes for males with autism spectrum disorder. Method To advance the development of a specialised autism screening tool for young males with FXS that could assist in early identification, backward regression was used to identify the combination of parent‐report questionnaire items that best predicted autism symptoms in a sample of 60 males with FXS, ages 4–18 years old. Results Both social and repetitive behaviours distinguished males with FXS/autism, with repetitive behaviours playing a more prominent role than previously documented in the literature. Conclusions Healthcare workers and early interventionists may be able to interview parents about a few key behaviours to determine if young child with FXS should be formally evaluated for autism. Evidence‐based practices identified for children with autism spectrum disorder can be implemented as early as possible.     

Narrative development in adolescents and young adults with fragile x syndrome

The narratives of 18 adolescents and young adults with fragile X syndrome were compared to those of 23 adolescents with Down syndrome and 21 typically developing children matched for nonverbal MA. Narratives were elicited using a wordless picture book and analyzed for use of narrative evaluation, linguistic productivity, and complexity. Results revealed that the individuals with fragile X syndrome produced significantly fewer different types of narrative evaluation, but more grammatically acceptable utterances than did the youth with Down syndrome. There was no significant difference between the participants with fragile X syndrome and their typically developing nonverbal-MA matches. Results suggest that a variety of language measures and contexts are needed to gain a full understanding of the language abilities of individuals with fragile X syndrome.     

Early identification of autism in fragile X syndrome: a review

Fragile X syndrome (FXS) is the leading genetic cause of autism, accounting for approximately 5% of autism cases with as many as 50% of individuals with FXS meeting DSM‐IV‐TR criteria for autistic disorder. Both FXS and idiopathic autism (IA) are attributed to genetic causes; however, FXS is an identified single gene disorder whereas autism is a complex disorder with multiple potential causes, some of which have been identified. Studies in IA have focused on the prospective longitudinal examination of infant siblings of children with autism as a target group due to their high risk of developing the disorder. We propose that this same model be applied to the study of infants with FXS. There is a lack of research focusing on the early development of autism within FXS and debate in the literature regarding how to best conceptualise this co‐morbidity or whether it should be considered a co‐morbid condition at all. Studying the emergence and stability of autism in infants with FXS has multiple benefits such as clarifying the underlying mechanisms of the development of autism in FXS and solidifying similarities and differences between co‐morbid FXS with autism and IA. Infant research in both IA and FXS are discussed as well as conclusions and implications for practice and future research.     

Motor abilities of children diagnosed with fragile X syndrome with and without autism

Background   Previous studies suggested that children diagnosed with fragile X syndrome (FXS) often meet criteria for autism or PDD. This study describes the fine motor abilities of children diagnosed with FXS with and without autism spectrum disorder, and compares the motor scores of those groups controlling for cognitive level.
Method   Forty-eight children, ages 12–76 months (SD = 16) diagnosed with FXS were assessed with the Mullen Scales of Early Learning, and the Autism Diagnostic Observation Schedule. Their parents were interviewed with the Autism Diagnostic Interview-Revised. We used a one-way analysis of variance to determine if the fine motor scale of the Mullen would show group differences based on autism classifications for the sample. In addition, we used Pearson correlation coefficient to examine the relationship between the cognitive level, the autism severity and the motor abilities. Lastly, we conducted a one-way analysis of covariance to determine the difference between the motor abilities of the Autism Spectrum Disorder groups controlling for cognitive level.
Results   We found that 60% of the children with FXS met criteria for autism or Pervasive Developmental Disorder – Not otherwise specified (PDD-NOS). Children with FXS with autism and PDD-NOS had lower fine motor scores than those without. However, there was no significant association between degree of motor impairment and communication and social impairments after controlling for cognitive level, indicating that cognitive level contributes to impaired motor abilities of children diagnosed with FXS and autism, more than the severity of autism symptoms.
Conclusion   children with FXS and autism are at risk for impaired motor abilities. Implications for development and intervention are discussed.     

Behavioral intervention for problem behavior in children with fragile X syndrome

Parents and professionals typically report problem behavior as a significant concern for children with fragile X syndrome. In the present study, the authors explored whether behaviorally based interventions would result in a reduction in problem behavior and an improvement in quality of life for 3 children with fragile X syndrome and their families. A multiple baseline design was used to demonstrate intervention effects for specific high-priority contexts (i.e., bedtime, running errands, and toileting). A multicomponent intervention plan was developed to teach the parents and child to effectively cope with the particular context. After intervention, there were substantial improvements in problem behavior and family quality of life within the given contexts. Results of this study demonstrated the effectiveness of behavioral intervention for children with fragile X syndrome.     

Linguistic and cognitive functioning and autism symptoms in young children with fragile X syndrome

Linguistic and cognitive profiles were examined in 18 children with autism and 18 children with fragile X syndrome (mean ages = 34 months). State-of-the-art diagnostic procedures for autism symptom identification were administered. Eight children with fragile X met criteria for autism. Comparison of linguistic and cognitive profiles (autism, fragile X without autism, fragile X with autism) revealed that children with fragile X (with autism) were more impaired in nonverbal cognition and expressive language. Receptive language was a relative strength for children with fragile X (without autism). There were no differences in receptive language in children with autism, regardless of fragile X status. Low receptive language may be a marker for autism symptoms in young children with fragile X.