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Friday, March 28, 2008

Early Diagnosis of Autism

Early Diagnosis of Autism

Autism is a behaviorally defined neurodevelopment disorder, which is the endpoint of several organic etiologies. The term "Autistic Spectrum Disorder" (ASD) is often used to include severe classic autism and other related conditions in the autism spectrum. Although its exact cause is not entirely known, it has been well established that early diagnosis and intervention are associated with better long-term results for management of the disorder.

But to the consternation of many parents, children with autism rarely receive a diagnosis before age 3 or 4. Early diagnosis is challenging because there is no laboratory test to detect it, nor one set of primary symptoms that define it. Therefore, the diagnosis is based on the presence or absence of a group of symptoms. Autism is difficult to diagnose in very young children because several of the disorder’s main symptoms—such as the child’s relationship with peers—involve behaviors that don’t fully develop in children until later in childhood. Diagnosis of autism is also difficult because the best early indicators involve the absence of consistent social and communication behaviors rather than the presence of an abnormality. There could be lots of reasons for not seeing a particular behavior because it’s either not developing, or it could be that the child is not showing it at that time. But behavioral researchers believe they are homing in on specific behaviors that should drop the age of first diagnosis down to as young as 18 months. Developmental researchers increasingly find that there are critical periods of child development after which certain systems—such as language, vision and motor skills—become less malleable. Therefore, it is speculated that if researchers can learn how to diagnose autism in children at birth or several months after, they may be able to design interventions which will arrest the disorder before it develops. As geneticists begin to locate potential 'autism genes', behavioral researchers are fast developing behavior-based diagnostic tools that will work at increasingly younger ages.

Although autism is usually diagnosed when the child is 3 to 4 years old, parents often sense that something is wrong much earlier. On average, parents start to worry about their child's development by 18 months of age and express their concerns by age 2. Early concerns noted by parents of children with autism can be due to additional learning disabilities rather than to specific impairments associated with autism. However, early videos taken by parents at around the first birthday may show the features which discriminate the child later diagnosed as having autism from other children of the same age .But physicians and professionals are hesitant to diagnose autism at very early ages because, the early development of children varies and often uncertain if a behavior will persist into being considered atypical. If the child is labeled with a problem too early, parents may reduce expectations for the child and restrict the child's access to typical experiences and opportunities. Thus, professionals may take on a "wait and watch" stance that delays diagnosis, and ultimately the commencement of intervention services. Although such concerns are valid, the benefits of early diagnosis vastly outweigh the risks. As many studies have now shown, early intervention is critical for the best outcome in children with autism. A developmental "window," that is, the readiness of the brain for a specific learning, is open only for a certain period. When that opportunity is missed, the learning is likely to be limited in spite of the best efforts. So, the earlier the diagnosis, the better is the prognosis. However, it has not been possible to act because we did not have effective means of evaluating and diagnosing the condition of autism in the first couple of years of life. An accurate diagnosis must be based on observation of the individual's communication, behavior, and developmental levels. However, because many of the behaviors associated with autism are shared by other disorders, various medical tests may be ordered to rule out or identify other possible causes of the symptoms being exhibited.

A brief observation in a single setting cannot present a true picture of an individual's abilities and behaviors. Parental (and other caregivers') input and developmental history are very important components of making an accurate diagnosis. At first glance, some persons with autism may appear to have mental retardation, a behavior disorder, problems with hearing, or even odd and eccentric behavior. To complicate matters further, these conditions can co-occur with autism.

Philip Teitelbaum (1998) reported that disturbance of movement in autistic child may be detected clearly at the age of 4-6 months and sometimes even at birth. The Eshkol–Wachman Movement Analysis System in combination with still-frame videodisc analysis was used to study videos obtained from parents of children who had been diagnosed as autistic by conventional methods, usually around 3 years old. The videos showed their behaviors when they were infants, long before they had been diagnosed as autistic. The movement disorders varied from child to child. Disturbances were revealed in the shape of the mouth and in some or all of the milestones of development, including, lying, righting, sitting, crawling, and walking. Every single autistic child demonstrated at least one movement disturbance by six months of age. Moebius mouth (flat lower lip and arched, oval shaped upper lip) was also present in a number of the children. According to Dr. Teitelbaum, not all autistic children have this feature, but when a child does have it, it’s a possible indicator of autism. And since the condition is noticeable in autistic infants as young as one month old, moebius mouth may prove to be one of the very earliest signs of the disorder. The findings support the view that movement disturbances play an intrinsic part in the phenomenon of autism, that they are present at birth, and that they can be used to diagnose the presence of autism in the first few months of life.

According to Professor Teitelbaum, autistic children learn to sit up, turn over and crawl in noticeably different manner than normal children. He believes that this difference in movement is caused by the same wiring problem in the central nervous system that later causes the social/verbal symptoms commonly associated with the condition.

Jennifer Pinto-Martin and Susan E Levy (2004) also noted disturbances of movement detected clearly at the age of 4-6 months, and sometimes even at birth using the same method. Many autistic children display hyperagility and hyperdexterity. In infancy, the movement disorders present in autism are clearest, not yet masked by other mechanisms that have developed to compensate for them. It is possible that they may vary according to the areas of the brain in which developmental delay or damage has occurred. For instance, Kemper and Bauman have pointed out from anatomical analysis of the brains of autistic individuals that the limbic system as well as the cerebellum may show small shrunken cells. Courchesne has evidence from MRI analysis that the cerebellum may show hypoplasia or even hyperplasia in certain regions of the cerebellum. By combining movement analysis in infancy with MRI analysis, it may be possible eventually to diagnose differential areas of brain involvement in different subtypes of autism.

In the screening for autism the following points are very important.
1) Does the baby respond to his or her name when called by the caregiver?
2) Does the young child engage in "joint attention"?
3) Does the child imitate others?
4) Does the child respond emotionally to others?
5) Does the baby engage in pretend play?

It is important to note that in each of the 5 areas concern is with behaviors that are absent or occur at very low rates. The absence of certain behaviors may be more difficult to pinpoint than the presence of atypical behaviors. But concerns in any of the above areas should prompt thorough evaluation for autism.

A "developmental screening" asking specific questions about baby's progress is very crucial in diagnosis of Autism. The role of pediatrician is very important. Several screening instruments have been developed to quickly gather information about a child's social and communicative development within medical settings.

Some screening instruments rely solely on parent responses to a questionnaire, and some rely on a combination of parent report and observation. Key items on these instruments that appear to differentiate children with autism from other groups before the age of 2 include pointing and pretend play. Screening instruments do not provide individual diagnosis but serve to assess the need for referral for possible diagnosis of ASD. These screening methods may not identify children with mild ASD, such as those with high-functioning autism or Asperger syndrome.

The second stage of diagnosis must be comprehensive in order to accurately rule in or rule out an ASD or other developmental problem. This evaluation may be done by a multidisciplinary team that includes a psychologist, a neurologist, a psychiatrist, a speech therapist, or other professionals.

Diagnostic Tools:
1. CARS (Childhood Autism Rating Scale), developed by Eric Schopler in the early 1970s. It aids in evaluating the child's body movements, adaptation to change, listening response, verbal communication, and relationship to people. It is suitable for use with children over 2 years of age. The examiner observes the child and also obtains relevant information from the parents. The child's behavior is rated on a 15-point scale based on deviation from the typical behavior of children of the same age

2. The Checklist for Autism in Toddlers (CHAT) is used to screen for autism at 18 months of age. It was developed by Simon Baron-Cohen in the early 1990s to see if autism could be detected in children as young as 18 months. The screening tool uses a short questionnaire with two sections, one prepared by the parents, the other by the child's family doctor or pediatrician.

3. The Autism Screening Questionnaire is a 40 item screening scale that has been used with children four and older to help evaluate communication skills and social functioning.

4. The Screening Test for Autism in Two-Year Olds, developed by Wendy Stone, uses direct observations to study behavioral features in children under two. She has identified three skills areas - play, motor imitation, and joint attention - that seem to indicate autism.

5. The Developmental Behaviour Checklist (DBC) Early Screen was developed by Ms Kylie Gray .The screening device is just for the use of GPs, pediatricians and early childhood services, to flag children who may be at risk of autism. The results will indicate if a child needs to be taken for specialist autism assessment.

6. Autism Diagnosis Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS-G). The ADI-R is a structured interview that contains over 100 items and is conducted with a caregiver. It consists of four main factors-the child's communication, social interaction, repetitive behaviors, and age-of-onset symptoms. The ADOS-G, designed by Catherine Lord, is an observational measure used to "press" for socio-communicative behaviors that are often delayed, abnormal, or absent in children with ASD.

7. The Early Screening for Autistic Traits or ESAT developed in Holland and designed to try to identify children with autism around age 15 to 18 months.

The problem with these screening tests is the opposite of what is expected. Missed diagnosis and misdiagnosis are common. The use of standardized assessment instruments and the strict application of the DSM and ICD diagnostic criteria need to be employed with caution. An expert clinical view has been shown to be more effective. An important aspect of early diagnostic consultation is an open and straightforward approach to the negotiation of the diagnostic view with parents over time.

Researchers face a paradoxical situation while developing behavioural tools for screening and diagnosing children with autism at age 2 and younger. It is difficult to prove that their early diagnosis was right if the children they diagnose at 18 months enter into interventions that help treat their dysfunction. It is difficult to say whether the diagnosis was wrong at age 2 or whether the intervention worked so well that the diagnosis is no longer valid.

That’s why most researchers hope they will find some biological markers .There is some progress in this area e.g. elevated levels of immune system B cells and natural killer cells, and more than 100 proteins (Amaral) and lower levels of cytokines (Water). Genetic markers for autism (e.g.endophenotypic traits such as large head size in family members, parents' abnormal brain processing of faces, and the degree to which relatives of autistic children can read another person's mental state) that could accurately diagnose autism at birth and would bolster the behavioral measures are being studied. Some teams are well on the way toward finding one or several autism genes, and others are using neuroimaging to search for specific anatomical or functional differences in the brains of people with autism.

Although autism is now agreed to be a neurobiological disorder, results from structural brain scans have not shown consistency of diagnostic markers. However, functional imaging has shown abnormalities of face processing (the area of the fusiform nucleus) in several studies. However, having something that is solid enough for diagnosing the disorder is still a far cry.


References:
1. Philip Teitelbaum, Osnat Teitelbaum, Jennifer Nye, Joshua Fryman, & Ralph G. Maureer (1998), Movement analysis in infancy may be useful for early diagnosis of autism. Psychology, Vol. 95, pp. 13982–13987,
2. Jennifer Pinto-Martin and Susan E Levy (2004), Early Diagnosis of Autism Spectrum Disorders. Current Treatment Options in Neurology 2004, 6:391-400
3. Lenny Schafer(2000).Guidelines for the Early Screening of Autism ;Early Detection Critical. The American Academy of Pediatrics
4. The Diagnosis of Autism: An Expert Interview with Catherine Lord, PhD; Posted 07/11/2005; http://www.ynhh.org
5. Kim Painter (2005). Autism now diagnosed early. Special for USA TODAY

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