Autism: Causes and Treatment Options

Abstract

Background

Cognitive defects in children are becoming a problematic concern in the recent period. Disorders like Autism have a major re to play in the development of several abnormalities related to speech, social interactions, verbal and non-verbal communications. These problems need to be assessed for lessening the incidence and prevalence of Autism and Autism Spectrum Disorders.

The main objective of this assignment is to perform a literature review and identify evidence-based reports keeping in view of the pathophysiology, and treatment options. Pubmed/Medline was accessed to retrieve the pertinent articles. Articles other than English were excluded. The reports have indicated the involvement of several etiological factors like genetical, biochemical, and diet. Genetic susceptibility to ASD was identified with markers like ADA 1 and ADA 2 in the majority of the population.

Biochemical alterations with regard to serotonin 5 hydroxytryptamine [5-HT], dopamine, and neuropeptide levels were also detected in Autistic children. Glutein rich diet, and secretin have also been found associated with the pathogenesis of Autism. There are inconsistent reports on laboratory evidence with regard to the sample size which is identified as major drawback in the findings.

It can be concluded that Autism is a severe cognitive disorder in children. Identification of patient population at the earliest is recommended. An evidence based practice approach is more suggestive for a concrete information and outcome evaluation.

However, research authorities should conduct intervention programs more focusing on The improvement of behavior, social interactions, learning abilities which enable the children to overcome various challenging tasks.

Introduction

Central Nervous System (CNS) related disorders affect various functional abilities that alter the quality of life. The susceptible group of patients may include children, adolescents or aged individuals. CNS disorders that affect at the earlier stages of life are problematic and are of much concern. One such disorder is Autism. It is initially diagnosed in the beginning stages of childhood. The symptomology includes alterations in the behavior, societal and communication patterns. Autism children talking difficulties, and may not be staring at eye during conversations. They often are repetitive in nature with respect to attention, pronunciation.

Autistic children express their happiness with hand waving or distract themselves to inform that they are unhappy. Very rarely, children with autism had talking difficulties throughout life. The symptoms of Autism are reported to diverse in their nature and as such they were grouped under a “spectrum” that comprises Autism. There are thorough investigations in progress world wide since many years aimed at finding out the exact cause and cure of this disorder. The present description is concerned with highlighting the available research evidence on the pathophysioogy and treatment options of Autism.

Causes

David and Christopher (2001) have reported that neurochemistry, neuroimaging, genetics, and pharmacologic treatment approaches have provided insights on the of causes of autism. Imaging technique like positron emission tomography is being exploited to determine autism in patients and has good implications (David and Christopher, 2001). Neurochemical studies have implicated the involvement of 5-HT dysregulation in autism (David and Christopher, 2001). Similarly, autoimmune and neuroendocrine factors have a great potential role in autism (David and Christopher, 2001). This may indicate that patients with Autism have a wide range of etiological factors that pose a silent threat to their life.

In detail, the causes of Autism are associated with the genetic predisposition. Serotonin transporter gene (HTT) was considered as a good candidate gene in autism due to the potency of serotonin transporter inhibitors in lessening the frequent episodes. This was revealed when a study was undertaken on the short variant of 5 HTT gene promoter region. Here, an analysis known as Preliminary transmission/disequilibrium test (TDT) was carried out in 86 families.

There was significant association between second intron locus in a multiallelic TDT and the haplotypes of the HTT promoter variant. This was strengthened by another report that described the connection between Autism and serotonin transporter (5-HTT) gene. Betancur et al (2002) have described polymorphisms at a functional deletion/insertion in the promoter region (5-HTTLPR) and other at a VNTR in intron 2, both belonging to human 5-HTT gene.

Family based investigations have already described the positive relationship between autism (Betancur et al., 2002).They emphasized on the inheritance of long and short alleles that were inherited in a priority manner(Betancur et al., 2002).

However, there were discrepancies due to inadequate support on the disequilibrium at the 5-HTTLPR locus inheritance (Betancur et al., 2002).This could be due to the presence of heterogeneity inherent in the clinical samples related to the raised serotonin (5-HT) blood levels, in few autistic patients (Betancur et al., 2002). Hence, the association between VNTR polymorphisms of the 5-HTT gene and 5-HTTLPR (Betancur et al., 2002). When the association between the whole blood 5-HT and 5-HTT variants was studied, transmission/disequilibrium test (TDT) indicated no linkage disequilibrium at either loci in 96 families that involved 53 sib pairs and 43 trios(Betancur et al., 2002).Therefore, 5-HTT gene could serve as a susceptibility factor in autism(Betancur et al., 2002).

Pahophyisiology

Aberrations in immunity and purine metabolism have been noted in the pathophysiology of Autism (Persico et al., 2000). Adenosine deaminase (ADA) an enzyme of the purine salvage pathway is associated with the regulation of these functions(Persico et al., 2000).It exists as ADA1 and ADA2 allozymes which are most abundant isomorphs in the population(Persico et al., 2000). These are coded by codominant ADA1 and ADA2 alleles. It was found that the individuals who possess single copy of the ADA2 allele have lower catalytic activity in contrast to ADA1 homozygous individuals (Persico et al., 2000). Autistic patients have more common ADA 2 alleles compared to healthy controls.

A case control study was undertaken to determine the linkages by employing a family-based strategy and to distinguish patients who are carry ADA2 in their genome by head circumference, peptiduria and serotonin blood levels (Persico et al., 2000). The alleles of ADA2 were found to be more significant in majority of Caucasian autistic patients who belong to Italian descent in contrast to normal individuals who served as controls and also their fathers (Persico et al., 2000). The Family tests that included extra Caucasian-American trios, and with independent families, were not in favor of satisfactory linkage (Persico et al., 2000).

The inheritance pattern of ADA2 alleles when repeated could reflect linkage disequilibrium between an imprinted gene variant situated in the immediate location and the ADA2 polymorphism(Persico et al., 2000).Hence, it could be inferred that distributions in ADA alleles linked to ethnic and racial disparities, small frequency of the ADA2 allele, were considered as likely problematic issues in the linkage studies(Persico et al., 2000). The determination of enzymatic activity of ADA in autistic patients and normal siblings who carry ADA1 and ADA2 genotypes could furnish efficient support for ADA2 involvement in autistic disorder (Persico et al., 2000).

The pathophsyiology of Autism or autism spectrum disorders (ASD) was considered complex as they have diverse behavior alterations that have a genetic etiology (Schanen, 2006). As such, pathways that were related to epigenetic control were described in patients with ASD that initiate from mutations of epigenetic origin like fragile X syndrome or that have association with vital epigenetic regulatory parameters (Rett syndrome) (Schanen, 2006).

It was described that the major frequent recurrent cytogenetic abnormalities in ASD has maternal duplications on the chromosome 15q11-13 where domain regions were imprinted (Schanen, 2006).Hence, the native parent influences the linkage and sharing on chromosomes 15q and 7q with imprinted regions (Schanen, 2006).This indicates that the imprinted regions require thorough evaluation from an epigenetic perspective, as epigenetic modifications do not induce variations in the primary genomic sequence (Schanen, 2006).This could facilitate risk epialleles to avoid identification using standard screening approaches.

Therefore, epigenetics plays key role in the etiopathogeneis of ASD (Schanen, 2006). Christopher et al (2005) have described that the pathophsyiology of Autism is better associated with neurochemical metabolites like neuropepties, Glutamine/ GABA systems, monoamines (5-HT, DA, NE). In several studies, the levels of monioamines in plasma, urine and CSF were reported to be negative(Christopher et al.,2005).

Whole blood serotonin (WBS) was higher in autistic patients categorized as “hyperserotonemic” (Christopher et al.,2005). The dysregulation of Opioid leading to low societal interactions, episodes of motor hyperactivity, elevated pain threshold were found in autistic children observed in earlier experiments(Christopher et al.,2005).Similarly, cortisol, secetin, melatonin levels have been evaluated in autistic patients and were hypothesized to have significant role in contributing to the autistic disorder through various pathways(Christopher et al.,2005).

Hence, the neurochemistry of Autism is complicated and works in well orchestrated manner in association with various metabolites.

Autism has link with gastrointestinal discomfort in children (Reichelt and Knivsberg, 2009). The pathogenesis emphasizes from the esophagus to the colon, reflecting the association between the magnitude of symptoms found in autistic children and the diet (Reichelt and Knivsberg, 2009). Altered intestinal permeability was considered as the problem and several theories have been put forward to indicate the development of leaky gut(Reichelt and Knivsberg, 2009).

These disturbances provide clues where altered gastrointestinal function could influence brain function (Reichelt and Knivsberg, 2009). Patients with Autism were found with increased urine peptide levels that have a dietary role. In this context, the patients were diagnosed keeping in view of DSM-III and DSM-IV criteria (Reichelt and Knivsberg, 2009). Urine samples that are having high creatinine content were subjected to high-performance liquid chromatography (HPLC).

This was accomplished by using acetonitrile and trifluoroacetic acid gradients in reversed phase C18 columns (Reichelt and Knivsberg, 2009). By employing 215 -275 nm absorption scale for peptide bonds the elution patterns were recorded for indolyl components and for aromatic groups (Reichelt and Knivsberg, 2009). In addition, Psycholinguistic Ability test, Progressive Matrices test of Raven’s and were incorporated administered before and following diet supplementation (Reichelt and Knivsberg, 2009).

Earlier in a nested case- control study, children with autism were assessed for gastrointestinal disorders (Corri, James, and Hershel, 2002). The factors considered were recurrent gastrointestinal symptoms, decreased food tolerance, coeliac disease, inflammation of the digestive tract (Corri, James, and Hershel, 2002). The findings have, however, not yielded significant information with regard to gastrointestinal disorders in children with Autism (Corri, James, and Hershel, 2002).

This may indicate that the involvement of gastrointestinal problems in autistic children needs further evaluation and confirmation. In countries like Australia, much research on Autism is in progress and there is a need to know about it. May et al. (2010) have emphasized on theories of autism where a compromised orbitofrontal cortex (OFC) compromise, defects in olfactory identification (OI) deficits are connected to OFC aberrations (May et al., 2010).

The objective of this research was to carry out studies in high-functioning autistic (HFA) children who are deficient in the normal age-OI association and make a comparison of unirhinal-OI in children with HFA, Asperger’s disorder (ASP), and normal controls(May et al., 2010). The findings have revealed decreased OI in few HFA children indicating OFC had diminished and there was heterogeneous OFC development (May et al., 2010).

This research has supported the hypothesis on different underlying neurobiological complications in ASP and HFA, with much emphasis on differential orbitofrontal functioning (May et al., 2010). Autism was reported to be associated with variations in diagnostic practices. To this end, a study determined the variations in ASD over time in Western Australia (WA) and the influence of changes in age at diagnosis, criteria of diagnosis, and requirements for service provision in the agreement with ASD diagnoses and changes in diagnostic approaches (Williams et al., 2008).

It was found that ASD incidence was associated with service provision changes in diagnostic practices in Western Australia (WA) (Williams et al., 2008). This has strengthened the inconsistent reports on if a rise in autism since earlier period could be a genuine rise or because of variations in diagnosis and autism spectrum disorders that include pervasive developmental disorder not otherwise specified (PDD-NOS), Asperger syndrome and Autism (Williams et al., 2008).

Treatment

Next, the treatment of Autism is varied in nature due to the heterogeneous nature of ASD. Sinha et al (2004) described Auditory integration therapy (AIT) an approach for enhancing altered sound sensitivity in individuals with behavioral disorders like autism(Sinha et al., 2004).

Apart from this therapy, there are several sound therapies that bear resemblance with AIT. These are Samonas Sound Therapy and Tomatis Method. Various experiments were carried out to evaluate the sound therapy efficacy (Sinha et al., 2004).The measurements used as outcomes for the stud are data representation in unusable forms, aberrant Behaviour Checklist subscores, and Fisher’s Auditory Problems Checklist (FAPC) (Sinha et al., 2004).The trials conducted using these outcome measures however, have not yielded much benefit with regard to AIT (Sinha et al., 2004).

The treatment of Autism with vitamins has become an important strategy. Pyroxidine (vitamin B6) was employed in children with “autism syndrome”(Nye and Brice, 2005). There was significant improvement in the language and speech due to high doses of B6 (Nye and Brice, 2005). Since the past 50 years, previous efforts with B6 therapy were targeted on physiological function, interpersonal attitude, non-verbal and verbal communication (Nye and Brice, 2005). However, due to inconsistent data on treatment studies with regard to B6, further studies were largely recommended with large sample size (Nye and Brice, 2005).

The excessive use of Gluten- and casein in diets was reported to contribute to Autism through their peptide content (Milliward et al., 2008). Here, aberrant levels of peptides in cerebrospinal fluid and urine were found in children autism (Milliward etal., 2008. In order to overcome this concern, the utility of complementary and alternative therapies (CAM) were focused on Autistic children by incorporating gluten and/or casein exclusion diets (Milliward et al., 2008).

But this approach too falls short of adequate research support for thorough evidence thus suggesting further studies (Milliward et al., 2008). Secretin as found to be a reliable treatment option for children with Autism (Williams, Wray, & Wheeler, 2005). It is a gastro-intestinal hormone considered to enhance the total clinical features of autism like behavior problems, communication and social interactions, enhancing the quality of life of affected autistic individuals and their care providers, prolonged effects on the outcome (Williams, Wray, & Wheeler, 2005).It was revealed that secretin recommendation intravenously as single or multiple dose could be made unless methodological problems of current research practices are overcome(Williams, Wray, & Wheeler, 2005).

Conclusion

In conclusion, children at very young age are falling victim to Autism or Autism Spectrum Disorders (ASD). The characteristic symptoms of this disorder include problems related to behavior, speech, verbal or nonverbal communication, cognitive defects. The pathophysiology of Autism has become complicated due its diverse nature of malformations and heterogeneity. Genetic susceptibility is identified as one of the risk contributors in pathogenesis. Various gene markers like ADA1 and 2 have been recognized. The biochemistry of this disorder was much emphasized on serotonin 5 hydroxytryptamine [5-HT], dopamine, and neuropeptides due to their abnormal levels.

Random studies undertaken in Australia have implied that the research on Autistic children is a progressing branch in the field of neuroscience. Treatment strategies have been explored since years. More probably vitamin B6 levels and glutein free diet have good implications in the near future inspite of certain discrepancies. There is need of undertaking large random studies for a thorough information. Research authorities may need to implement n evidence based paradigm for the alleviating of Autism disorders in child

References

1. Autsim. Web.
2. David J. Posey and Christopher J. McDougle. (2001). ‘The pathophysiology and treatment of autism’. Current Psychiatry Reports, 3(2), pp. 101-108.
3. Cook, E,H Jr., Courchesne, R., Lord, C., Cox, N,J., Yan, S., Lincoln, A., Haas, R., Courchesne, E., Leventhal, B,L. (1997). ‘Evidence of linkage between the serotonin transporter and autistic disorder’. Mol Psychiatry, 2(3), pp.247-50.
4. Betancur, C., Corbex, M., Spielewoy, C., Philippe, A., Laplanche, J,L., Launay ,J.M., Gillberg, C., Mouren-Siméoni, M,C., Hamon, M., Giros, B., Nosten-Bertrand, M., Leboyer, M. (2002). Serotonin transporter gene polymorphisms and hyperserotonemia in autistic disorder. Mol Psychiatry,7(1),67-71.
5. Persico, A,M., Militerni, R., Bravaccio, C., Schneider, C., Melmed, R., Trillo, S., Montecchi, F., Palermo, M,T., Pascucci, T., Puglisi-Allegra, S., Reichelt, K,L., Conciatori, M., Baldi, A., Keller, F. (2000). Adenosine deaminase alleles and autistic disorder: case-control and family-based association studies. Am J Med Genet, 96(6), pp.784-90.
6. Schanen, N,C. (2006). Epigenetics of autism spectrum disorders. Hum Mol Genet, 15 Spec2, pp.R138-50.
7. Reichelt, K, L.,& Knivsberg, A,M. (2009). ‘The possibility and probability of a gut-to-brain connection in autism’. Ann Clin Psychiatry,21(4),pp.205-11.
8. Corri Black, James, A Kaye, Hershel Jick. (2002). Relation of childhood gastrointestinal disorders to autism: nested case-control study using data from the UK General Practice Research Database. BMJ, 325, pp. 419.
9. May, T., Brewer, W,J., Rinehart, N,J., Enticott, P,G., Brereton, A,V., Tonge, B,J. (2010). Differential Olfactory Identification in Children with Autism and Asperger’s Disorder: A Comparative and Longitudinal Study. J Autism Dev Disord.
10. Nassar, N., Dixon, G., Bourke, J., Bower, C., Glasson, E., de Klerk, N., Leonard, H. (2009). Autism spectrum disorders in young children: effect of changes in diagnostic practices. Int J Epidemiol,38(5),pp. 1245-54.
11. Nye, C., Brice, A. (2005). ‘Combined vitamin B6-magnesium treatment in autism spectrum disorder.Cochrane Database Syst Rev,19,4. Web.
12. Millward, C., Ferriter, M., Calver, S., Connell-Jones, G. (2008). ‘Gluten- and casein-free diets for autistic spectrum disorder’. Cochrane Database Syst Rev. 16,2. Web.
13. Williams, K,W., Wray, J,J., Wheeler, D,M.(2005). Intravenous secretin for autism spectrum disorder. Cochrane Database Syst Rev.20(3),pp. Web.