![]() They found no statistically significant associations between thimerosal exposure from vaccines early in life and six of the seven neuropsychological constructs examined.Ĭoncern regarding the safety of childhood vaccines has had a major impact on immunization rates ( 13– 16). ( 11), they found a significant association between thimerosal dosage and tics, but only in boys. ( 12) examining a subset of the data from Thompson et al. The only variable that was statistically significant was tics children who were exposed to higher doses of thimerosal were more likely to exhibit tics. The data included the evaluation of 1,047 children and their biological mothers and 24 neuropsychological tests. ( 11), who investigated the association between TCVs and immune globulins early in life and neuropsychological outcomes in children at 7–10 y of age. ![]() ![]() Significant associations have been reported by Thompson et al. Several epidemiological studies sought to determine whether TCVs resulted in neurodevelopmental disorders including autism however, both nonsignificant and significant associations have been reported ( 8– 12). A more recent second review of TCVs and autism (IOM 2004) ( 7) came to the same conclusion reached earlier: that there was no epidemiological data to support a relationship between TCVs and childhood developmental disorders. The IOM review did, however, note the possibility of such a relationship and recommended further studies be conducted. Results from an Institute of Medicine (IOM) review on the safety of childhood vaccines found that there was not sufficient evidence to render an opinion on the relationship between exposure to TCVs or the measles, mumps, rubella (MMR) vaccine and developmental disorders in children (IOM 2001) ( 6). In many autism studies, comorbid conditions such as seizure disorders or intellectual disabilities contribute to the heterogeneity of the neuropathology.Īn association between exposure to thimerosal-containing vaccines (TCVs) and developmental abnormalities has been debated since 1999 when the US Food and Drug Administration determined that children receiving multiple TCVs at a young age were at risk for exceeding the Environmental Protection Agency’s safe exposure limits for methylmercury (MeHg). Thus far, the major neuropathological changes observed in autism are changes in neuronal size in the limbic system decreased numbers of Purkinje cells in the cerebellum abnormalities in the brainstem, neocortex, amygdala, and hippocampus features of cortical dysgenesis or migration disturbances and alterations in GABAergic and cholinergic systems. The neuropathology of autism is now beginning to be understood however, there is still much to be learned. Genetic and environmental factors have been found to play a role in the disorder ( 3, 4). ASD is defined by the presence of marked social deficits, specific language abnormalities, and stereotyped repetitive patterns of behavior ( 2). These data indicate that administration of TCVs and/or the MMR vaccine to rhesus macaques does not result in neuropathological abnormalities, or aberrant behaviors, like those observed in ASD.Īutism spectrum disorder (ASD) is a complex neurodevelopmental disorder presenting in early childhood with a current prevalence ranging from 0.7% to 2.64% in the United States ( 1). Analysis of social behavior in juvenile animals indicated that there were no significant differences in negative behaviors between animals in the control and experimental groups. No neuronal cellular or protein changes in the cerebellum, hippocampus, or amygdala were observed in animals following the 1990s or 2008 vaccine schedules. Using infant rhesus macaques receiving thimerosal-containing vaccines (TCVs) following the recommended pediatric vaccine schedules from the 1990s and 2008, we examined behavior, and neuropathology in three brain regions found to exhibit neuropathology in postmortem ASD brains. Some anecdotal reports suggest that ASD is related to exposure to ethyl mercury, in the form of the vaccine preservative, thimerosal, and/or receiving the measles, mumps, rubella (MMR) vaccine. Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |