Sample Paper on MMR Vaccine and Autism

MMR vaccine and autism

Introduction

Autism spectrum disorder (ASD) is an amalgam of neurodevelopment disorders that are manifested as mild to severe deficiencies in social and communication interactions coupled with limited, repetitive and stereotypical behavioral patterns (American Psychiatric Association, 2012).  The spectrum of disorders that are associated with autism include but are not limited to autistic disorder, Asperger disorder as well as pervasive developmental disorder not otherwise specified, among others, which may occur independently or jointly in a patient. ASD being a behavior disorder requires a comprehensive behavioral evaluation making it extremely difficult to diagnose and time consuming in diagnosis because of the complexity of the screening features needed to accurately diagnose the disorder. The symptoms associated with ASD become apparent in children who are as young as 18 months making it necessary for children to be screened for the disorder by the time they clock 24 months to help in instituting early intervention measures (Johnson & Myers, 2007; Zwaigenbaum et al., 2005). For children who have delayed speech, it is difficult for early diagnosis to be done because a behavioral analysis is possible mainly from engaging with the child through questions. However, as children reach the school-going age, there is an increasing likelihood for autism to be diagnosed because for children to access special education services, they must demonstrate that they suffer from a disability.

The number of autism cases being diagnosed being reported has risen to alarming levels and there have been suggestions that the increase in the number of children being diagnosed may be due to some specific causative agent. There was controversy in 1998 when Wakefield et al. (1998) published an article I the Lance claiming that there was a link between the MMR vaccine and the increased incidence of autism diagnosis, leading to panic over the safety of vaccines being administered to children. The article led to increased research in ASD as many scholars tried to replicate Wakefield’s findings and establish a definitive link between the vaccines and the disorder. However, most of the research conducted showed that there was no definitive link between the MMR vaccine and increased autism incidence because although the coverage of the MMR vaccine has been at an average of 95% for successive annual birth cohorts, there has been an increase in the number of diagnosed cases over the same period (Kaye et al. 2001; Taylor B et al. 1999). The increased research following the alleged link between MMR and ASD had the beneficial effect of increasing the current understanding on autism through the generation of quality data. Therefore, the recent increase in diagnosed cases on Autism is due to the fact that we now have a much better understanding of Autism and its spectrum disorders.

The diagnosis of ASD is complicated by the fact that the disorder neither has any biological markers that can form a framework for diagnosis nor easy to access symptoms. Consequently, the increase in diagnosis of the disease may have been due to diagnostic substitution, where an individual is diagnosed of one condition and subsequently at a later time diagnosed of another condition due to changes in standards, practices and procedures of diagnosis (Coo et al., 2008; Bishop et al., 2008).

Methods

The data used in this paper was obtained by searching academic databases using a number of keywords and phrases to limit the number of articles chosen. The US National Library of Medicine database was used as the source of the scholarly articles used in this article. In addition the period of consideration was limited to articles published from 2009 to 2015 to ensure that only the latest data and development from the field of autism diagnosis was used. The key phrases used were; ‘increase in autism prevalence’, ‘changes in autism diagnostic standards, practices and procedures’ and ‘diagnostic substitution in autism diagnoses”. Each of these search terms was entered into the Pub Med search engine and a number of articles containing the key words were listed. Content and thematic analysis of each of the articles was done to ensure that the chosen articles contained the relevant information needed for the literature review.

Results

The data generated from each of the search key words is shown below

Key Words Number of articles Number of articles

2009-2015

Thematically Relevant

Articles

Increase in autism prevalence 375 222 167
Changes in autism diagnostic standards, practices and procedures 4 3 2
Diagnostic substitution in autism diagnosis 13 13 9

 

Table 1: Key word search results

From the data the greatest numbers of scholarly articles address the issue of the increasing prevalence of ASD showing that the increasing prevalence of the disease is a worrying trend whose cause ought to be determined. The need to understand the causes and reasons leading to the increasing incidence have led to an explosion in research data related to the causative agents of the disease. Research on ASD is no longer limited to the patient but has been widened to incorporate the parents, especially the mother, and environment as possible causative agents for the disorder.

There are three articles that were recorded in the second search parameter of changes in the diagnostic standards, methods and procedures in the diagnosis of autism. Lastly, there are 9 articles that were recorded in the third search parameter of diagnostic substitution. It is necessary to note that a thematic analysis of the data set obtained shows that the articles selected for review often have information that overlaps across the three parameters, especially in the first search parameter of increase in autism prevalence.

Discussion

The graph below represents the changes in autism caseload in California between 1992 and 2005. The section of the graph that is shaded grey represents the increase in the number of autism cases, while the black portion of the graph represents the portion of the recorded increase that is due to change in the change in diagnostic procedures.

Fig. 1. Autism incidence over time; Figure adopted from King & Bearman (2009)

Between 1993 and 1999, there is a relatively gradual increase in the number of persons diagnosed with autism and the proportion of the total number of those who are diagnosed due to a change in the diagnosing methods is negligible. However, between 2000 and 2004 there is a steep rise in the number of people being diagnosed of autism before the rise slowing down after 2004. The corresponding proportion of those who are diagnosed of autism due to a change in diagnostic procedures increases relatively sharply between 2001 and 2005 year-on-year with no signs o slowing down. The rise in the proportion of patients being diagnosed with autism due to changes in diagnosis approach rises sharply after 1999. This rise is not coincidental as it happens after Wakefield et al. (1999) published an article linking the MMR vaccine to increased incidence of autism. The claim led to an increase in research on the disorder, and consequently there was a lot of data on the disorder, helping health practitioners to develop better diagnostic procedures. Increased interest in autism in the recent past has also meant that there is continuous research in the field, and hence there is a greater understanding on the causes of the disorder compared to a few years ago. The knowledge gained from the research has been instrumental in developing new diagnosis frameworks and tools, making it easier to for health practitioners to identify the disorder early enough to allow for the implementation intervention measures. Although there has been a general increase on the number of people being diagnosed with autism, the exact reason as to why the increase has happened is yet to be established. Change in screening procedures in itself cannot fully account for the rapid increase in the number of people diagnosed with the disease.

There has been a concerted effort to identify some of the likely triggers of autism in children as a means of mitigating the risks and helping to reduce the risk of young children developing the disorder. The table below summarizes the relationship between the use of formula milk and autism incidence in young children

Fig, 2. Relationship between increasing autism incidence and use of formula milk; Figure adopted from Zhou et al. (2013)

The use of infant formula has been identified as one of the likely causative agents of increased autism incidence in young children. The number of children diagnosed with autism between 1980 and 1986 when infant formula was introduced was relatively small and rose modestly year-on-year. However, between 1987 and 1992 when advertisements to popularize infant formulas were run, there is an explosion I the number of young children diagnosed with autism as more parents chose to give their children the formulas instead of breast milk. From the rapid increase in the number of children being diagnosed with autism, it can be inferred that the rise in incidence is related to the use of infant formulas.

Research on the causative agents as well as the environmental triggers of autism has been done and there is a wealth of information on the likely cause of autism in children. In reviewing literature, Curran et al posit that a child’s susceptibility to ASD begins right from birth, with children born through C-sections having a greater probability of developing ASD as they grow. When a child is in the womb, it is enveloped by the environment provided by the mother’s womb and does not come into contact with the general environment easily. However, if the child is exposed to particulate matter at either the prenatal or postnatal stages, there exists a window in which the child will be susceptible to getting autism (Kalkbrenner et al., 2015). One of the pre-birth triggers for autism in children has been the use of oral contraceptives by the mother (Strifert, 2015), and hospitalization of the mother during pregnancy due to infection (Lee et al., 2015). Maternal health has a big impact on the probability of a child developing autism because the hormones released by the mother’s body circulate in the blood stream and can have a detrimental effect on the development of the child. When a mother is suffering from posttraumatic stress, her child’s susceptibility to ASD is likely to increase as maternal stress is transmitted to the child (Roberts, et al., 2014). When children are born pre-term, they are easily exposed to perinatal inflammation, considering that they are not fully developed. These children are at a heightened risk of developing ASD due to the infections that they may pick, which interfere with normal growth and development. ASD cannot be caused by physical and environmental factors only but may also be cause by genetic factors which predispose a child towards developing the disorder. In a study, Waltes et al. (2014) found that some of the genetic risk factors for autism were variations in genes of the postsynaptic FMRP signaling pathway which changed and adversely affected the development of the child leading to development of ASD. Research on the effect of genes on the probability of a child developing autism shows that polymorphisms in the HFE gene considerably increase the chances of children developing the ailment. Gene related triggers of autism are difficult to control because they are harder to spot in addition to there being no definitive link between the gene processes and autism. Autism is difficult to manage through gene therapy because ASD involves a number of disorders with varying degrees of severity, which also do not have any specific gene markers hat can be manipulated to treat the disorder.

The question that scholars are increasingly asking is whether the much heralded increase in the number of people diagnosed with ASD is a phantom increase, one that is being highlighted because previously undiagnosed patients are now being diagnosed with ASD mainly due to an improvement in the screening procedures. In a study to determine whether the rise in number of reported cases was incidental, Nassar et al. (2009) conducted a population-based study using a number of young children, in their study, they found that there was a steady increase in the number of children being diagnosed with ASD every year. However, they also found that despite the general increase in the numbers, the number of children diagnosed with severe ASD had declined while the numbers for those diagnosed with mild to moderate ASD had increased. The increase in  the number of those diagnosed with severe to mild ASD coupled with a fall in the number of those diagnosed with severe ASD seems to suggest that the increase in the ASD caseload may be mainly due to improved diagnostic procedures which have allowed medical practitioners to identify the disorder even in its mild form.

Conclusion

ASD is currently an issue of great concern to the medical practitioners as well as the general public because its incidence is increasing and the suffering of the children is a matter of concern especially for their teachers. The exact cause of the disorder remains unknown and there is no known cure despite the resources that have been invested to find one. Managing of children with the disorder is a challenge to tutors and the children often need financial aid to be able to access special needs education considering that they cannot survive the normal classes. More research needs to be done to better understand the likely causative agents of the disorder as a basis for addressing the disorder and obtaining a cure. The rising incidence of ASD should be taken in context because some of the figures that are presented are not of new cases but of cases that have been undiagnosed due to previously inefficient and insufficient screening mechanisms. Finally, although ASD makes the life of the children to be difficult due to their inability to socialize freely or communicate effectively, the condition is not fatal, and if well-managed, a child can grow up and continue with his life as near normally as possible.

 

References

American Psychiatric Association. (2000) Diagnostic and statistical manual of mental disorders. 4th ed. Washington, DC: American Psychiatric Association.

Bishop D, Whitehouse A, Watt H, Line E. (2008). Autism and diagnostic substitution: evidence from a study of adults with a history of developmental language disorder. Dev Med Child Neurol, 50:341–45.

Coo H, Ouellette-Kuntz H, Lloyd J, Kasmara L, Holden J, Lewis S. (2008). Trends in autism prevalence: diagnostic substitution revisited. J Autism Dev Disorders, 38:1036–46.

Curran EA, O’Neill SM, Cryan JF, Kenny LC, Dinan TG, Khashan AS, Kearney PM. (2014). Research Review: Birth by caesarean section and development of autism spectrum disorder and attention-deficit/hyperactivity disorder: a systematic review and meta-analysis. J Child Psychol Psychiatry. doi: 10.1111/jcpp.12351.

Kalkbrenner AE, Windham GC, Serre ML, Akita Y, Wang X, Hoffman K, Thayer BP, Daniels JL. (2015). Particulate matter exposure, prenatal and postnatal windows of susceptibility, and autism spectrum disorders, Epidemiology 26(1):30-42.

Kaye JA et al. (2001). Mumps, measles, and rubella vaccine and the incidence of autism recorded by general practitioners: a time trend analysis. BMJ, 322:460-63.

King, M. & Bearman, P. Diagnostic change and the increased prevalence of autism. International Journal of Epidemiology, 38(5): 1224–1234.

Lee BK, Magnusson C, Gardner RM, Blomström Å, Newschaffer CJ, Burstyn I, Karlsson H, Dalman C. (2015). Maternal hospitalization with infection during pregnancy and risk of autism spectrum disorders. Brain Behav Immun, 44:100-5.

Roberts AL, Koenen KC, Lyall K, Ascherio A, Weisskopf MG. (2014). Women’s posttraumatic stress symptoms and autism spectrum disorder in their children. Res Autism Spectr Disord, 8(6):608-616.

Strifert, K. (2015). The link between oral contraceptive use and  prevalence in autism spectrum disorder. Med Hypotheses. 83(6):718-25.

Taylor B et al. (1999). Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association. Lancet, 353 (9169):2026-9.

Wakefield AJ et al. (1998). Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children.  Lancet, 351(9103):637-41.

Waltes R, Duketis E, Knapp M, Anney RJ. et al. (2014). Common variants in genes of the postsynaptic FMRP signaling pathway are risk factors for autism spectrum disorders. Hum Genet, 133(6):781-92.

Zhou, S.,, Zhou, M., Li, D. & Ma, Q. (2013). Early infant exposure to excess multivitamin: a risk factor for autism? Autism Res Treat, 2013:963- 967.

Zwaigenbaum L, Bryson S, Rogers T, Roberts W, Brian J, Szatmari P. (2005). Behavioral manifestations of autism in the first year of life. International Journal of Developmental Neuroscience, 23(2–3):143–52.