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Una publicación sobre discapacidades visuales, y sordera y ceguera, para familias y profesionales.

Spring 99 Table of Contents
Versión Español de este artículo (Spanish Version)

By Marnee Loftin, Psychologist, Texas School for the Blind and Visually Impaired

Pervasive Developmental Disorder is a psychiatric/psychological term for a broad category of disorders characterized by disturbed patterns of social interaction and language. PDD is also accompanied by a variety of unconventional self-stimulatory behaviors. These conditions are all generally noted early in life and often associated with an additional diagnosis of mental retardation. Although the specific cause of PDD is not known, it is often associated with other medical conditions, such as chromosomal abnormalities, congenital infections, and structural abnormalities of the central nervous system.

Within this broad category of PDD, there are four different types of disorders. These vary primarily according to the age at which the behaviors are first observed. Numerous excellent resources are available that completely describe each of these types of PDD. The following is a brief summary regarding each of these types.


  • This disorder is only reported in females.
  • Profound to severe retardation is most likely to occur.
  • Symptoms first appear after the age of five months, with the condition usually being diagnosed in the first four years of life.

Characteristics include:

  • Normal development through the age of five months and then loss of skills;
  • Loss of purposeful hand movements between five and ten months of age with subsequent development of a stereotyped hand movement that resembles hand wringing or hand washing;
  • Poorly coordinated gait or trunk movements;
  • Severe impairment of both expressive and receptive language as well as physical movement.

Childhood Disintegrative Disorder

  • Recent data suggests that it is more likely to occur in males.
  • Onset is most frequently noted between three and four years of age.
  • Frequently the onset is preceded by periods of irritability, increased activity level, and anxiety.

Characteristics include:

  • Normal development through the first two years of life and then progressive loss of skills;
  • Impairment in social interactions, communication, or presence of stereotyped patterns of behavior.

Autistic Disorder

  • This disorder is most frequently noted in males.
  • Mental retardation is an accompanying disorder in approximately 75% of the cases.
  • Profiles in psychological testing will often show an extreme pattern of strengths and weaknesses. This is present even in cases where mental retardation is also present.
  • Symptoms first appear before the age of three years.
  • Generally the diagnosis will be based upon behaviors that are exhibited after the age of two years because of the subtle manifestations of Autistic Disorder during infancy.

Characteristics include:

  • Impairment in social relationships such as: difficulty in developing peer relationships that are appropriate to their developmental level, lack of social or emotional reciprocity, lack of any attempts to share enjoyment, interest, or achievement with others;
  • Impairment in communication such as: delay or lack of development of spoken language, no attempt to compensate for this lack, marked difficulty in initiating or sustaining conversation;
  • Idiosyncratic language such as lack of make believe play appropriate to their developmental level;
  • Stereotyped and repetitive behavior, interests and activities such as: preoccupation with certain objects or activities, inflexible adherence to routines, repetitive motor movements, preoccupation with parts of objects.

Asperger's Disorder

  • This disorder is most frequently noted in males.
  • Intelligence is most frequently in the normal range, but will sometimes be as low as borderline.
  • No delays are noted in language development, cognitive development, or areas of adaptive behavior, with the exception of social behaviors.
  • The disorder will most likely will be diagnosed in adolescence or as a young adult.
  • Psychological assessments will generally reveal high scores on items that measure memory, but lower on items that measure social comprehension and judgment.

Characteristics include:

  • Impairment in social relationships such as: failure to develop peer relationships, lack of social and emotional reciprocity, lack of seeking to share enjoyment, interest, or achievement with others;
  • Stereotyped and repetitive behavior, interests and activities such as: preoccupation with objects or activities, inflexible adherence to routines, repetitive motor movements, preoccupation with parts of objects.

Difference Between Autism and Asperger's Disorder

Though there are some similarities between Autism and Asperger's Disorders, there are also significant differences, including the following:

  • Individuals with Autistic Disorder will generally have no interest or awareness in others. Individuals with Asperger's are often keenly interested in and aware of others, but do not have the skills to engage them successfully.
  • There is no delay in language development in individuals with Asperger's Disorder. Frequently their language skills are well developed, but often quite bookish. They will talk for long periods of time with considerable knowledge about topics that others are not interested in discussing.
  • Motor skills are often an area of significant strength for individuals with Autistic Disorder. Individuals with Asperger's are often quite clumsy and poorly coordinated.
  • Individuals with Autistic Disorder will often have an area of interest/ability that is a splinter skill. For example, they may be able to tell the day on which a certain date will occur. Individuals with Asperger's will have an interest that will become an obsession. The various topics may change (for example from discussing snakes to discussing railroads) and the amount of information will be factually correct but excessive in discussions.
  • The diagnosis of Asperger's usually occurs much later than that of Autistic Disorder. The social and communication deficits are much less severe, and are often perceived as something that the child will "grow out of" as they approach adulthood. This is a significant factor in the relatively late identification of Asperger's.
  • Often there are motor mannerisms in a person with Asperger's that may not originally be seen as self-stimulatory behaviors. They are subtler and include behaviors such as flicking of fingers, manipulating glasses in a stereotypic manner, etc. Generally these behaviors will become less frequent as the child becomes older. They may reemerge in times of stress. The self-stimulatory behaviors in an individual with Autistic Disorder are more intense and are likely to appear more unusual. In addition, rates of self-stimulatory behaviors tend to remain high even as the child becomes older.
  • Individuals with Asperger's seldom have the neurological disorders that are commonly seen in Autistic Disorder.


At this time there is no specific test or instrument to diagnose Asperger's. Much of the decision is based upon observation of the student as well as reports of family members and staff.

In general, individuals with Asperger's exhibit a number of disturbances in interpersonal relationships. They may express considerable interests in developing these relationships, but find this difficult to do. Relationships with peers are frequently one-sided with long conversations about a limited number of topics. Generally the topics will focus upon their own narrow topics of interest. They are unable to gauge the degree of interest (or disinterest) that others may have in their conversations. When peers attempt to direct their conversations to mutual topics of interest, the individual with Asperger's will ignore such attempts. They may refuse to respond or will simply redirect it back to their own area of interest.

In general, the topics of extreme interest for an individual with Asperger's are those that can best be learned in a rote manner such as weather, geography, construction, etc. They are less likely to choose topics that focus upon more aesthetic interests or abstract concepts. The topics may change over a period of time, and the individuals may not want to discuss topics that interested them during an earlier stage of development.

Individuals with Asperger's are quite often bright individuals who learn well in role play situations regarding specific social skills. However, they have great difficulty in generalizing a skill learned in one situation to another situation.

Psychological assessments will often reveal a pattern of strengths and weaknesses that is quite pronounced. These individuals have skills in rote learning of verbal concepts and verbal memory. They often have a large vocabulary and can easily repeat long strings of information. Reading skills are likely to be well developed, but they often have great difficulty making inferences based upon reading. Weaknesses are most obvious in tactile perception, psychomotor coordination, visual-spatial organization, and situations that involve interpretation of social cues.

One of the most difficult tasks in diagnosing Asperger's Disorder is to differentiate between this disorder and other conditions, specifically Attention Deficit Disorder and Anxiety Disorders.


At this time, there is no specific treatment or "cure" for Asperger's Disorder. Intervention usually consists of different psychological strategies or medication. Both types of intervention deal with decreasing the symptoms that appear. Examples of psychological strategies that might be used include:

  • Behavior intervention plans to increase the rate of appropriate peer interactions;
  • Role play various situations to increase skills to empathize with others;
  • Specific social skills training to improve basic skills in group and individual interactions.

Medications are available to treat a variety of behaviors that are exhibited. Psychiatric consultation is critical in making such a decision. Different medications have been used to address the following groups of behaviors:

  • Hyperactivity, inattention, and impulsivity
  • Irritability and aggression
  • Preoccupations, rituals, and compulsions
  • Anxiety

PDD and Visual Impairments Diagnosis

The diagnosis of both Autistic Disorder and Asperger's Disorder is a complex task that is even more difficult when the child is severely visually impaired. Although the cause of PDD is not clearly established, PDD is often associated with congenital infections and structural abnormalities of the central nervous system. Both of these conditions are also often seen as causes of visual impairment. Therefore children with visual impairment may in fact be at increased risk for some type of PDD. The diagnosis of any form of PDD is challenging. That task is significantly more complicated in children with visual impairments because of their unique developmental patterns.

In spite of these difficulties, in recent years we have seen a significant increase in the number of young children with visual impairments who have also been diagnosed as having some form of PDD.

Two issues are critical in this process. (1) Someone with a clear understanding of the unique developmental patterns of visually impaired children should be involved in the diagnostic process, to differentiate and note behaviors that may be of concern. For example, echolalic language and difficulties in establishing peer relationships are frequent issues in young children with visual impairments. These behaviors have little diagnostic significance (i.e., not necessarily indications of Autism) although they may be noted as areas of need for remediation in the educational programs. (2) Many young children with visual impairments have great difficulty in establishing peer relations because of the lack of opportunities for incidental learning. This should be identified as a need for direct training rather than a symptom of Asperger's.

After areas of need are identified, our responsibility as educators is to allow adequate time for maturity to occur and new skills to be learned. For the vast majority of children with visual impairments, these behaviors and concerns will correct themselves with appropriate instruction and maturation.

When these behaviors continue to remain problematic, we need to ask ourselves why. We can be sensitive to the different developmental patterns of children with severe visual impairments, but we must not let this interfere with our ability to determine when these differences have become significant deviations from the usual developmental patterns for children. An important goal is to develop consistent means of gathering data that will allow us to monitor changes in social interactions, communication, and ritualistic/stereotypic behaviors that occur as a child matures and education progresses. Appropriate identification of children with visual impairments and some type of PDD will allow modifications of their educational program and better access to adult services.