Pervasive Developmental Disorder NOS Causes

(Also Known As: Pervasive Developmental Disorders Causes, Autism Causes, Asperger's Causes, Aspergers Causes, Pervasive Developmental Disorder Not Otherwise Specified Causes, Pdd-NOS Causes, PDD Causes)

(Reviewed by: Paul Peterson, Licensed Therapist)

What are the causes of pervasive developmental disorder NOS?

Causes of pervasive developmental disorder NOS and Asperger’s syndrome are unknown, but family studies suggest a highly possible link to autism. The similarity of PDD-NOS and Asperger’s disorder to autistic disorder supports the presence of genetic, metabolic, infectious and perinatal predisposing factors.

Psychosocial and Family Factors

In 1943, a researcher, Leo Kanner, indicated that only few parents of autistic children were warmhearted while most of them were preoccupied with intellectual abstractions. The mother usually lack emotional responsiveness, and this is pointed out as liable for autism conditions. This idea, however, needs stronger evidence to further support its claim. Other theories such as parental rage and rejection and parental reinforcement of autistic symptoms are also unsupported. Moreover, comparison of parents with autistic children to parents with normal children showed no significant differences in child-rearing skills.

Biological Factors

The biological basis for autism lies in the high incidence of mental retardation in children with autistic disorder, as well as the intensely increased rate of seizure disorders which even exceeds the expected ratio.

  • Approximately 75% of autistic children also have mental retardation
  • About 1/3 of these children have mild to moderate mental retardation
  • Almost half of them are severely mentally retarded

Children with autism and mental retardation typically manifests markedly poor abstract reasoning, social understanding and verbal tasks as compared to performance tasks, such as block design and digit recall.

Autistic disorder is also associated with neurological conditions, congenital rubella, phenylketonuria (PKU), and other inborn error of metabolism which may lead to mental retardation, tuberous sclerosis and Rett’s disorder. In addition, autistic children having more minor congenital physical anomalies are suggestive of abnormal development within the first trimester of pregnancy.

Genetic Factors

Autism and other PDDs are greatly influenced by genetic factors. Siblings of autistic children are most likely to develop autism as well. Recent studies show extremely strong evidence that two regions in chromosomes 2 and 7 contain genes involved in autism. These genes may also be found in chromosomes 16 and 17 but the strength of the correlation is weaker.

Immunological Factors

According to reported studies, immunological incompatibility such as maternal antibodies directed to the fetus may bring about autism. Lymphocytes will react with maternal antibodies thus damaging extraembryonic tissues during gestation.

Perinatal Factors

Perinatal complications are a few of the predisposing factors to autism. These include maternal bleeding after first trimester, meconium in the amniotic fluid. During the neonatal period, autistic children often have conditions of respiratory distress syndrome and neonatal anemia.

Neuroanatomical Factors

Brain enlargement has been suggested as a possible biological marker for autistic disorder. Autistic individuals have larger total brain volume as compared to normal individuals. The increased volume arises from three different mechanisms: increased neurogenesis, decreased neuronal death and increased production of nonneuronal brain tissue such as glial cells or blood vessels.

Biochemical Factors

High plasma serotonin concentrations were found on the blood of affected individuals. However, this finding is not a specific diagnostic marker for autism alone because patients with mental retardation also manifest this trait. High concentrations of the major dopamine metabolite, homovanillic acid in CSF is associated with increased withdrawal and stereotypes in some cases of autism. There are also findings that symptoms are alleviated as the ratio of the serotonin metabolite, 5-hydroxyindoleaceticacid (5-HIAA), to homovanillic acid increases. The concentration of 5-HIAA in the CSF is inversely proportional to serotonin concentrations. This trait is increased in approximately one third of autistic disorder patients, which is also a non-specific finding that occurs in mentally retarded patients. 4

Could You Have Pervasive Developmental Disorder NOS?

Pervasive Developmental Disorder NOS Topics

Related Conditions

Asperger's Syndrome – impaired social interaction, restrictive patterns of behavior, repetitive behavior, autism, clumsiness
Autism – impaired social interaction, restricted repetitive behavior, impaired social development
Childhood Disintegrative Disorder – disintegrative psychosis, developmental delay, impaired social, verbal and motor skills
Rett's Disorder – impaired social skills, autism, pervasive disorder, cognitive impairment, impaired verbal skills