Difference between PDD and Autism

PDD vs Autism

The past few decades have seen a sharp rise in developmental disorders in children. Diagnoses of disorders like epilepsy, autism, non verbal learning disorder, pervasive developmental disorders, etc have become fairly commonplace. For a parent whose child has just been diagnosed with one of these disorders, it can be a life-altering event. It is important to understand the difference between these disorders because they often seem to overlap and confuse.

Pervasive developmental disorder (PDD) is an umbrella term that includes five diagnoses- autism, Asperger’s syndrome, Rett syndrome, childhood disintegrative disorder and PDD-not other specified (PDD-NOS). PDD is a disorder of developmental delay of skills like communication and socialization. Each of the above mentioned disorders have a few symptoms which are predominant and help in diagnosing the condition. PDD-NOS is often loosely referred to as PDD by many doctors. Autism is a specific developmental neuropsychiatric disorder characterised by poor social skills, language and communication problems and stereotyped or repetitive behaviour.

The exact cause for either PDD or autism is not known but multiple theories float. Theories suggest autism could be due to certain maternal behaviours like smoking/alcoholism during pregnancy, genetic mutations, drugs used in vaccines for children, environmental causes like heavy metals and pesticides. None of them has strong conclusive evidence although genetic theory is strongest possibility and evidence so far.
Symptoms of PDD are difficulty in relating to objects, events, people; lack of facial expression and poor eye contact; restricted routines with poor adjustment to change in routine and new surroundings; difficulty in understanding and using language; difficulty in controlling emotions and behaviour in social situations; etc. Children having PDD are very different as regards their intelligence, abilities and intensity of behaviour. There are children ranging from those who don’t speak at all to those who have almost normal language skills; some children are even gifted with special skills like music, painting and do exceptionally well in these fields despite other sensory and motor problems.

Children with autism have repetitive and restricted behaviours like flapping hands for hours; poor social and communication skills often making them socially withdrawn and isolated; they often have difficulty in imaginative play and at least a third do not develop enough speech to manage daily communication; self-injurious behaviour like head banging against a wall, hand biting are often seen; compulsive behaviour like arranging objects in rows; difficulty sharing experiences, requests. There is also delay in developmental milestones with poor muscle tone and toe walking. Autistic savants are children with autism who are prodigious and rare talents like memorizing entire books or playing music. High functioning autism is another category of children who have almost normal language and social skills.

Diagnosis for both disorders is made by IQ tests and other clinical tests designed to assess language, sensory and motor perception, etc. No blood tests or imaging modalities are available that diagnose either disorders.

Treatment is based on symptomatic palliation. Children with accompanying anxiety, restlessness, epilepsy, etc are treated for those with drugs. Speech therapy, behaviour therapy, occupational therapy and other specially designed courses are available for improving the sensory and motor skills. Cure has still not been noted, although children with early diagnosis and intervention can manage a daily life with rigorous therapy.

Take home pointers:

PDD and autism are developmental disorders that lie along the same spectrum with small differences in manifestations. Delay in social and communication skills, sensory and motor skills along with restricted or repetitive behaviours are common to both with varying intensity.
The exact cause of either is not known and both are incurable. No blood tests are diagnostic for either of these conditions.

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