The history of vaccinations in the light of the autism epidemic.

Autism has been characterized as a behavioral disorder since it was first described by Leo Kanner in 1943. The number of autistic children has increased over the last decade. The incidence of autism was 1 in 10000 before the 1970s and has steadily increased to 1 in 150 in 2008 with a male:female predominance of 4:1. The cause of this epidemic has remained unknown, but several hypotheses have been studied. Many of these suggest an environmental trigger, such as the ethyl mercury contained in the preservative thimerosal, which has been used in vaccines since 1931. Other possible triggers associated with vaccinations are chemical toxins and live viruses. James has published studies suggesting a genetic predisposition in the families of autistic children, exposing them to a deficiency in glutathione and an inability to detoxify heavy metals. Vargas has shown autism to encompass ongoing inflammation in the brains of autistic children. The Hannah Poling vaccine decision was a landmark case. Poling's family was awarded funds for ongoing medical care of an autistic child who was found to have mitochondrial dysfunction exacerbated by vaccines that left her with autistic behavior and seizures. Several studies have emerged supporting the fact that a significant number of autistic children do have mitochondrial dysfunction. The impact that the Poling case will have on the ability of parents of autistic children to gain access to funds to enable them to properly care for their children remains to be seen.

Hyperbaric oxygen treatment in autism spectrum disorders.

Traditionally, hyperbaric oxygen treatment (HBOT) is indicated in several clinical disorders include decompression sickness, healing of problem wounds and arterial gas embolism. However, some investigators have used HBOT to treat individuals with autism spectrum disorders (ASD). A number of individuals with ASD possess certain physiological abnormalities that HBOT might ameliorate, including cerebral hypoperfusion, inflammation, mitochondrial dysfunction and oxidative stress. Studies of children with ASD have found positive changes in physiology and/or behavior from HBOT. For example, several studies have reported that HBOT improved cerebral perfusion, decreased markers of inflammation and did not worsen oxidative stress markers in children with ASD. Most studies of HBOT in children with ASD examined changes in behaviors and reported improvements in several behavioral domains although many of these studies were not controlled. Although the two trials employing a control group reported conflicting results, a recent systematic review noted several important distinctions between these trials. In the reviewed studies, HBOT had minimal adverse effects and was well tolerated. Studies which used a higher frequency of HBOT sessions (e.g., 10 sessions per week as opposed to 5 sessions per week) generally reported more significant improvements. Many of the studies had limitations which may have contributed to inconsistent findings across studies, including the use of many different standardized and non-standardized instruments, making it difficult to directly compare the results of studies or to know if there are specific areas of behavior in which HBOT is most effective. The variability in results between studies could also have been due to certain subgroups of children with ASD responding differently to HBOT. Most of the reviewed studies relied on changes in behavioral measurements, which may lag behind physiological changes. Additional studies enrolling children with ASD who have certain physiological abnormalities (such as inflammation, cerebral hypoperfusion, and mitochondrial dysfunction) and which measure changes in these physiological parameters would be helpful in further defining the effects of HBOT in ASD.