Portal:Pervasive developmental disorders

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The diagnostic category pervasive developmental disorders (PDD), as opposed to specific developmental disorders (SDD), is a group of five disorders characterized by delays in the development of multiple basic functions including socialization and communication. The pervasive developmental disorders are: All autism spectrum disorders and Rett syndrome.

The first four of these disorders are commonly called the autism spectrum disorders; the last disorder is much rarer, and is sometimes placed in the autism spectrum and sometimes not.

Pervasive developmental disorders

Autism is a developmental disorder characterized by difficulties with social interaction and communication, and by restricted and repetitive behavior. Parents usually notice signs during the first three years of their child's life. These signs often develop gradually, though some children with autism reach their developmental milestones at a normal pace before worsening.

Globally, autism is estimated to affect 24.8 million people . In the 2000s, the number of people affected was estimated at 1–2 per 1,000 people worldwide. In the developed countries, about 1.5% of children are diagnosed with ASD , from 0.7% in 2000 in the United States. It occurs four-to-five times more often in males than females. The number of people diagnosed has increased dramatically since the 1960s, partly due to changes in diagnostic practice. The question of whether actual rates have increased is unresolved.

Rett syndrome (RTT) is a genetic brain disorder that typically becomes apparent after 6 to 18 months of age in females. Symptoms include problems with language, coordination, and repetitive movements. Often there is slower growth, problems walking, and a smaller head size. Complications can include seizures, scoliosis, and sleeping problems. Those affected, however, may be affected to different degrees.

Rett syndrome is due to a genetic mutation of the MECP2 gene. This gene occurs on the X chromosome. Typically it develops as a new mutation, with less than one percent of cases being inherited from a person's parents. It occurs almost exclusively in girls. Boys who have a similar mutation typically die shortly after birth. Diagnosis is based on symptoms and can be confirmed with genetic testing.

Asperger syndrome (AS), also known as Asperger's, is a developmental disorder characterised by significant difficulties in social interaction and nonverbal communication, along with restricted and repetitive patterns of behavior and interests. As a milder autism spectrum disorder (ASD), it differs from other ASDs by relatively normal language and intelligence. Although not required for diagnosis, physical clumsiness and unusual use of language are common. Signs usually begin before two years of age and typically last for a person's entire life.

The exact cause of Asperger's is unknown. While it is probably partly inherited, the underlying genetics have not been determined conclusively. Environmental factors are also believed to play a role. Brain imaging has not identified a common underlying problem. In 2013, the diagnosis of Asperger's was removed from the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), and people with these symptoms are now included within the autism spectrum disorder along with autism and pervasive developmental disorder not otherwise specified (PDD-NOS). It remains within the International Classification of Diseases (ICD-11) but as a subtype of autism spectrum disorder.

Childhood disintegrative disorder (CDD), also known as Heller's syndrome and disintegrative psychosis, is a rare condition characterized by late onset of developmental delays—or severe and sudden reversals—in language, social function, and motor skills. Researchers have not been successful in finding a cause for the disorder. CDD has some similarity to autism, and is sometimes considered a low-functioning form of it. In May 2013, the term CDD, along with other types of autism, was fused into a single diagnostic term called "autism spectrum disorder" under the new DSM-5 manual. Therefore, CDD is now also called "regressive autism", being that this term can now refer to any type of autism spectrum disorder that involves regression, including CDD.

CDD was originally described by Austrian educator Theodor Heller (1869–1938) in 1908, 35 years before Leo Kanner and Hans Asperger described autism. Heller had previously used the name dementia infantilis for the syndrome.

A pervasive developmental disorder not otherwise specified (PDD-NOS) is one of the four autism spectrum disorders (ASD) and also one of the five disorders classified as a pervasive developmental disorder (PDD). According to the DSM-IV, PDD-NOS is a diagnosis that is used for "severe and 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 PDD" or for several other disorders. PDD-NOS is often called atypical autism, because the criteria for autistic disorder are not met, for instance because of late age of onset, atypical symptomatology, or subthreshold symptomatology, or all of these. Even though PDD-NOS is considered milder than typical autism, this is not always true. While some characteristics may be milder, others may be more severe.

Did you know?

...that an autistic savant (historically described as idiot savant) is a person with both autism and Savant syndrome? Savant Syndrome describes a person having both a severe developmental or mental handicap and extraordinary mental abilities not found in most people. The Savant Syndrome skills involve striking feats of memory and often include arithmetic calculation and sometimes unusual abilities in art or music.

Selected article

Controversies in autism

There is considerable disagreement over the exact nature of autism; however, it is generally considered to be a neurodevelopmental condition that manifests in markedly abnormal social interaction, communication ability, patterns of interests, and patterns of behavior. It encompasses a wide range of atypical conditions, none of which is well understood. Although there are common and specific physical conditions comorbid to autism spectrum disorders, not all people diagnosed with autism spectrum disorders experience these. The diagnostic criteria, as of 2006, are still generally limited to psychiatric and cognitive evaluation methods with IQ score and a particular patterns of abilities (common to those with autism) featuring strongly in the formal diagnosis of autism and distinguishing it from Asperger syndrome at the time of diagnosis.

Related articles

The following are articles directly related to Pervasive Developmental Disorder related conditions:
Asperger syndrome
Autism and working memory
Autism Diagnostic Observation Schedule
Autism spectrum disorders
Autism-spectrum quotient
Autistic enterocolitis
Autism spectrum
Communication disorder
Conditions comorbid to autism spectrum disorders
Developmental disability
Genetic disorder
High-functioning autism
Isodicentric 15
Language delay
Learning disability
Mental illness
Mirror neuron
Multiple complex developmental disorder
Nonverbal learning disorder
Pervasive developmental disorder
Picture thinking
Regressive autism
Sensory defensiveness
Sensory processing disorder
Sensory overload

The following are conditions that often occur together with a diagnosis on the Autistic Spectrum or PDD:
Antisocial personality disorder
Attention deficit hyperactivity disorder
Auditory processing disorder
Clinical depression
Conduct disorder
Down syndrome
Developmental coordination disorder
Fragile X syndrome
Intellectual disability
Obsessive–compulsive disorder
Oppositional defiant disorder

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Selected biography

Tito Rajarshi Mukhopadhyay (born 1989 in India) was diagnosed in early childhood with severe or low functioning non-verbal autism. He first came to the attention of the west through autism researcher Richard Mills, who met Tito in Bangalore, India and arranged for him to travel to the UK to be assessed by his colleagues at the National Autistic Society and Lorna Wing. At the same time the BBC made the documentary 'Tito's Story' and the National Autistic Society published his first book, 'Beyond the Silence' (2000). He provides insights into the nature of his autism, according to Autism Speaks, the former Cure Autism Now, and scientists who studied his case, such as Michael Merzenich.

Selected images

Pervasive developmental disorders and the autistic spectrum

In practice, an autistic spectrum disorder and pervasive developmental disorder are synonymous, but making a distinction is valuable. Pervasive developmental disorder refers to those psychological and behavioural developmental disorders encompassing many areas of functioning: language and communication, self-help skills, motor coordination, executive function, and scholastic achievement. The nosological category of pervasive developmental disorders includes syndromes that may be etiologically unrelated to autism, with autistic-like behaviour being only one part of the disorder: Rett's syndrome and childhood disintegrative disorder.

Autism, Asperger syndrome and pervasive developmental disorder not otherwise specified are generally the disorders associated with the autistic spectrum.


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