Autism Spectrum Disorders

a. Autism

B. Childhood Disintegrative Disorder

c. Rett Syndrome

d. PDD-NOS

 

The diagnostic category of pervasive developmental disorders (PDD) refers to a group of four (4) disorders characterized by delays in the development of multiple basic functions, including socialization, communication, and adaptive skills.

 

 

Autism

Extract from L. M. McGrath & R. L. Peterson’s book chapter

 

 

Diagnostic Features

Autism is a developmental brain disorder that is part of the autism spectrum and is sometimes referred to as an autism spectrum disorder.  Autism first appears during infancy or childhood, and generally follows a steady course without remission.  Symptoms tend to continue through adulthood, although often in more muted form. It is distinguished not by a single symptom, but by a characteristic triad of symptoms: impairments in social interaction; impairments in communication; and restricted interests and repetitive behavior. Other aspects, such as atypical eating, are also common but are not essential for diagnosis. 

 

There are three main areas of difficulty which all people with autism share and which are sometimes known as the 'triad of impairments'. They are: 

 

Qualitative difficulties with social communication

 People with autism have difficulties with both verbal and non-verbal language. Many have a very literal understanding of language, and think people always mean exactly what they say. They can find it difficult to use or understand: 

  • facial expressions or tone of voice. 

  • jokes and sarcasm. 

  • common phrases and sayings. 

Some people with autism may not speak, or have fairly limited speech. They will usually understand what other people say to them, but prefer to use alternative means of communication themselves, such as sign language or visual symbols.  Others will have good language skills, but they may still find it hard to understand the give-and-take nature of conversations, perhaps repeating what the other person has just said (this is known as echolalia) or talking at length about their own interests.

 

Qualitative difficulties with social interaction

 People with autism often have difficulty recognizing or understanding other people's emotions and feelings, and expressing their own, which can make it more difficult for them to fit in socially. As a result, they may have marked impairment in the use of multiple nonverbal behaviors, such as eye-contact, facial expression, posture, and gestures to regulate social interaction; they may:

  • have marked impairment in the use of multiple nonverbal behaviors, such as eye-contact, facial expression, posture, and gestures to regulate social interaction;

  • not be able to understand the unwritten social rules which most of us pick up without thinking: such as standing too close to another person, or starting an inappropriate subject of conversation;

  • appear to be insensitive because of not recognizing how someone else is feeling;

  • prefer to spend time alone rather than seek out the company of other people;

  • not seek comfort from other people; and

  • appear to behave inappropriately, as it is not always easy for them to express their feelings, emotions or needs. 

Making and maintaining friendships often proves difficult for those with autism; however, for them, the quality of friendships, not the number of friends, predicts how lonely they feel.

 

Qualitative difficulties with symbolic play and social imagination

Difficulties with social imagination mean that people with autism find it hard to:

  • understand and interpret other people's thoughts, feelings and actions.

  • predict what will happen next, or what could happen next

  • understand the concept of danger; for example, that running on to a busy road poses a threat to them. 

  • engage in imaginative play and activities: children with autism may enjoy some imaginative play, but prefer to act out the same scenes each time. 

  • prepare for change and plan for the future. 

  • cope in new or unfamiliar situations.

Children and adults with autism may have preoccupations with one or more stereotypical and restricted patterns of interests, abnormal either in intensity or focus. Also, compulsive adherence to specific non-functional routines or rituals, and stereotyped and repetitive motor mannerisms (e.g., hand or finger flapping, or twisting, or complex whole body movements). 

 

Qualitative Description

Classification of autism is derived from cognitive and adaptive scores and has three levels: mild, moderate, severe.

 

Mild Autism. Children with mild autism are usually high functioning; they have higher cognitive abilities and, most often, limited range of interests, repetitive play skills and impaired social skills.

 

Moderate Autism. Children with moderate autism have much higher perceptual reasoning abilities than verbal reasoning skills. As a consequence, they have difficulty with abstract concepts. In addition, they have limited range of interests and impaired social skills.

 

Severe Autism: Children with severe autism have cognitive abilities and adaptive skills that are below average. Repetitive movements, resistance to change in environment or routine are common, as well as unusual responses to sensory experiences, lack of verbal and nonverbal communication, and behavioral difficulties.

 

 

Diagnostic instruments

Best practice parameters recommend that an ASD assessment should include an assessment of the child’s cognitive and academic abilities as well as adaptive skills, so that the behavioral symptoms can be interpreted within the context of the child’s developmental level. 

 

Instruments used in the diagnosis of children suspected of having autism include those which are based on structured interviews with parents and other caregivers, behavior rating scales, and other objective behavior assessment systems.  Most questionnaires assess the severity of autism behavior e.g., the Childhood Autism Rating Scales (CARS) yield a composite score ranging from non-autistic to mildly autistic, moderately autistic, or severely autistic.

 

Other diagnostic instruments include:

  • Autism Spectrum Rating Scales (ASRS)

  • Social Communication Questionnaire (SCQ)

  • Gilliam Autism Rating Scale (GARS),

  • Autism Diagnostic Observation Schedule (ADOS),

  • Autism Spectrum Screening Questionnaire (ASSQ),

  • Checklist of Autism in Toddlers (CHAT),

  • Screening Tool for Autism in Two-Year-Olds (STAT), and the

  • PDD Assessment Scale/Screening Questionnaire.

 

Differential Diagnosis

ASD overlaps with Intellectual Disabilities, Language Impairment, and anxiety disorders (including obsessive-compulsive disorder).  Symptoms of inattention and hyperactivity are quite common in ASD.  Also, autistic individuals experience seizure activity. Autism or PDD must be differentiated from Rett’s Disorder, Childhood Disintegrative Disorder (CDD), and a residual diagnosis, PDD, not otherwise specified (PDD-NOS). 

 

Autism involves multiple learning disabilities, including a specific language impairment, social cognition disability, semantic pragmatic disorder, hyperlexia, and motor problems.  If a specific learning disability coexists with autism, this is to be listed so that specific interventions and strategies can be designed to help.  

 

Prevalence and Etiology

In recent reports, the prevalence of autism is about 6 per 1,000 people, with about four times as many males as females affected.  The number of people known to have autism has increased since the 1980s, partly due to changes in diagnostic practices. 

 

Symptoms of autism result from maturation-related changes in various systems of the brain, the precursors of which are genetic mutations.  Current evidence suggests that autism may be a disorder of neuronal connectivity (e.g., orbitofrontal-limbic, amygdaloid-temporal association cortex tracts) and that deficits in social cognition and communication in autism may be related to dysfunction in the amygdala, hippocampus, and related limbic and cortical structures. Other neuroanatomical structures, such as the cerebellum, also may form part of a distributed neuronal network responsible for social cognition and communication.

 

Interventions and Strategies

Medications are used to address certain behavioral problems. Therapy for children with PDD should be specialized according to the child’s specific needs.  Some children with PDD benefit from specialized classrooms in which the class size is small and instruction is given on a one-to-one basis.  Others function well in standard special education classes or regular classes with support.  Early intervention, including appropriate and specialized educational programs and services play a critical role in improving the outcome for individuals with PDD. 

 

References

McGrath L. M., & Peterson, R. L.  (2009).  Autism spectrum disorder: A neurological Framework .  In B. F. Pennington (Eds.), Diagnosing learning disorders (2nd Ed., PP. 108-151). New York, NY: The Guilford Press. 

Jansen, J. E. (2003).  Understanding the nature of Autism (2nd ed.).St. Antonio: CA: The Psychological Corporation.

 

 

Childhood Disintegrative Disorder

 

 

Diagnostic Features

The essential feature of Childhood Disintegrative Disorder is a significant regression in multiple areas of functioning following a period of at least 2 years of apparent normal development. Apparent normal development is reflected in age-appropriate verbal and nonverbal communication, social relationships, play, and adaptive behavior. After the first 2 years of life (but before 10 years of age), the child has a clinically significant loss of previously acquired skills in at least two of the following areas: expressive or receptive language, social skills or adaptive behavior, bowel or bladder control, play, or motor skills. Individuals with this disorder exhibit the social and communicative deficits and behavioral features generally observed in Autistic Disorder. There is also qualitative impairment in social interaction and in communication, as well as restricted, repetitive, and stereotyped patterns of behavior, interests, and activities.

 

Differential Diagnosis

Childhood Disintegrative Disorder is usually associated with Severe Mental Delay. Various nonspecific neurological symptoms or signs may be noted. There seems to be an increased frequency of EEG abnormalities and seizure disorder.  The condition is occasionally observed in association with a general medical condition (e.g., metachromatic leukodystrophy, Schilder's disease) that might account for the developmental regression. In most instances, however, extensive investigation does not reveal such a condition.

 

Also, Childhood Disintegrative Disorder must be differentiated from other Pervasive Developmental Disorders (PDD’s) as well as from a dementia with onset during infancy or childhood: i.e., Dementia infantilis.  Dementia per se occurs as a consequence of the direct physiological effects of a general medical condition (e.g., head trauma), whereas Childhood Disintegrative Disorder typically occurs in the absence of an associated general medical condition.

 

Prevalence and Etiology

Childhood Disintegrative Disorder appears to be very rare and much less severe than Autistic Disorder. Although initial studies suggested an equal sex ratio, the most recent data suggest that the condition is more common among males.

 

Usually the loss of skills reaches a plateau, after which some limited improvement may occur, although improvement is rarely marked. In other instances, especially when the disorder is associated with a progressive neurological condition, the loss of skills is progressive. Childhood Disintegrative Disorder follows a continuous course and in the majority of cases, the duration is lifelong. The social, communicative, and behavioral difficulties remain relatively constant throughout life. 

 

Rett syndrome

 

 

Diagnostic Features

Rett Syndrome (RS) is a neurological disorder seen most often in females. The child with RS usually shows an early period of apparently normal or near normal development until 6-18 months of life. A period of temporary stagnation or regression follows during which the child loses communication skills and purposeful use of the hands. Soon, stereotyped hand movements, gait disturbances, and slowing of the rate of head growth become apparent. Other problems may include seizures and disorganized breathing patterns which occur when awake. Apraxia (dyspraxia), the inability to program the body to perform motor movements, is the most fundamental and severely handicapping aspect of RS. It can interfere with every body movement, including eye gaze/contact and speech, making it difficult for the person with RS to do what she wants to do.

 

Differential Diagnosis

Rett Syndrome is most often misdiagnosed as autism, cerebral palsy or non-specific developmental delay.

 

Prevalence and Etiology

The prevalence rate in various countries is from 1:10,000 to 1:23,000 live female births. Most researchers now agree that RS is a developmental disorder rather than a progressive, degenerative disorder as once thought.

 

Rett syndrome is caused by mutations (structural alterations or defects) in the MECP2 gene, which is found on the X chromosome  The MECP2 gene contains instructions for the synthesis of a protein called methyl cytosine binding protein 2 (MECP2), which acts as one of the many biochemical switches that tell other genes when to turn off and stop producing their own unique proteins.

 

There are four stages of Rett syndrome. Stage I, called early onset, generally begins between 6 and 18 months of age.  Stage II, or the rapid destructive stage, usually begins between ages 1 and 4 and may last for weeks or months. This stage may have either a rapid or a gradual onset as purposeful hand skills and spoken language are lost.  Stage III, also called the plateau or pseudo-stationary stage, usually begins between ages 2 and 10 and can last for years. Apraxia, motor problems, and seizures are prominent during this stage.  The last stage, stage IV — called the late motor deterioration stage — can last for years or decades and is characterized by reduced mobility. Muscle weakness, rigidity (stiffness), spasticity, dystonia (increased muscle tone with abnormal posturing of extremity or trunk), and scoliosis (curvature of the spine) are other prominent features. Generally, there is no decline in cognition, communication, or hand skills in stage IV. Repetitive hand movements may decrease, and eye gaze/contact usually improves.

 

References

Lindberg, B.  (2006).  Understanding Rett Syndrome: A practical guide for parents, teachers, and therapists (2nd ed.).  Toronto, Canada: Hogrefe and Huber Publishers.

 

 

Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS)

 

 

Diagnostic Features

PDD-NOS is characterized by pervasive impairment in the development of reciprocal social interaction or verbal and nonverbal communication skills or when stereotyped behavior, interests, and activities are present but the criteria are not met for a specific pervasive developmental disorder, fragile x syndrome, schizophrenia, schizotypal personality disorder, or avoidant personality disorder.

 

PDD-NOS is sometimes called Atypical Autism.  A person with PDD-NOS is often described as being high-functioning; in other words, the individual’s autism symptoms do not affect him or her as severely as a person with autistic disorder.  Many times, these persons do well academically, can learn social skills, and gain appropriate motor skills.

 

Criteria for diagnosis.

Specific criteria must be met in order for a diagnosis PDD-NOS. Symptoms may include:

·         Significant impairment in communication.

·         Lack of eye contact.

·         Self-stimulatory behaviors or repetitive movements.

·         Unusual focus on certain interests.

·         Significant impairment in social interaction.

·         Rigid patterns of behavior.

Prevalence and Etiology

Some clinicians use PDD-NOS as a “temporary” diagnosis for children under five.  The assumption is that by the age of 5, unusual behaviors will either resolve or develop into diagnosable autism.  PDD-NOS may turn, at times, into more specific diagnoses as the child moves into his teens.  However, given support and therapy, the symptoms will attenuate over time.