For decades, the medical and scientific communities have been attempting to discover the causal factors for autism spectrum disorder because during the last few decades its prevalence has dramatically risen. This, of course, is a major problem because the debilitating disorder can make everyday activity a struggle. With that said, some previous investigators have presumed the onset of autism is due to genetic mutations while others suggest diagnostic substitution from other diagnoses, such as mental retardation (MR) and/or cerebral palsy (CP) to pervasive developmental disorder (PDD), are contributing factors behind the increased rates of autism.
However, this suggestion of diagnostic substitution made autism researchers and expert David A. Geier investigate that theory of autism onset. They examined medical records with SAS® and StatsDirect software for subjects within the Vaccine Safety Datalink database that were HMO-enrolled at birth until they were diagnosed with an International Classification of Disease (ICD-9) outcome of PDD, MR or CP. After examination of the data, they suggest that diagnostic substitution cannot fully explain the increased prevalence of PDD during the 1990s in the United States.
Autism falls under the diagnostic category of pervasive development disorders (PDD) and the diagnosis typically occurs before a child reaches the age of 3. They may demonstrate problems with social and communication skills like difficulties relating to people, playing with toys in unusual ways and showing body movement or behavior patterns in a repetitive manner. At any rate, the researchers cite that the prevalence of PDD has increased 20 to 30 fold since studies were conducted during the ’60s and ’70s as it was estimated to only affect 1 in 2,500 children or 0.04%. However, by the 2000s, the prevalence changed to 1% to 2% of all children.
The goal was to find out why it rose and previous research was attempting to presume the increase was due to diagnostic substitution from other diagnoses was the ultimate reason. But, that was not the case as the data from the VSD database was significantly different populations and the differences in that diagnostic substitution cannot explain the increase of PDD cases in the US. Additionally, as time progressed, more environmental factors have come into play like the number of childhood vaccinations, which many of the vaccines are formulated with toxic compounds like aluminum and mercury. Both toxins have been extensively study and research has produced strong evidence that they can affect the central nervous system and neurodevelopment. All of which purport toxic exposure and the possible onset of autism spectrum disorder and other neurological conditions.