Autism

Introduction

Every human being passes through different stages of development between birth and adolescence. It involves both physical as well as neurological changes. The individual undergoes psychological as well as emotional development occurring simultaneously. The developmental process is divided into different milestones to assess the developmental process taking place in a child. 

Autism is a developmental disorder seen in early childhood. This disorder is characterized by the behavior of social withdrawal and isolation. The patients fail to develop social and communication skills as they grow. The signs of autism begin to appear in early childhood when the neurological development does not synchronize with the physical development of the individual. 

Autism can result due to genetic as well as environmental causes. Certain risk factors during pregnancy may also make the child susceptible to this developmental disorder. In the USA, every 10 out of 10,000 children have autism. Most of the pediatricians recommend autism screening at 16 to 24 months of age. 

In this article, we will discuss the classification of autism, its causes, clinical features as well as management of the patients.

Clinical Features

Autism is a prototype of pervasive developmental disorders (PDD) that appears in children younger than 3 years. Autism covers a wide spectrum of signs and symptoms that continue to worsen with age. Most of the patients are severely impaired in some aspects of life but are superior or normal in other aspects as well. The signs are first noticed by the parents of the child. The pediatrician also performs routine developmental tests for autism screening.

The major clinical features in autism involve impairments in social development, communication, as well as repetitive behavior. Some other symptoms are also seen in such patients. The details of these clinical manifestations are given below. 

Impairments in Social Development

Defects in social development are important features of autism and related pervasive developmental disorder. Different signs start appearing in early childhood indicating unusual social development. The social behavior of autistic patients is clearly different from normal children. 

The signs indicating defective social behavior progress with age. 

During infancy, the signs include;

• Less smile
• Less attention to different social stimuli
• Looking at other people less often

The signs seen in toddlers with autism include the following;

• Inability to point at things
• Less eye-contact
• Inability to use movements for expressing 
• Inability to participate in the turn-taking process

Children of three to five years of age with autism have the following signs of defective social development; 

• Inability to express social understanding
• Inability to participate in non-verbal communications
• Inability to imitate
• Inability to show an emotional response

As the children grow, the social development worsens. The teenagers and adults with autism are unable to express themselves emotionally. They are also very poor at recognizing facial expressions. These individuals also have less attachment security as compared to non-autistic persons. 

Autistic patients also fail to make friends. They are reluctant to go to social gatherings. They often feel lonely. It is difficult for them to make friends. 

It has also been found that aggression and violence are also seen in autistic patients. It is more commonly seen in children having intellectual disabilities along with autism. 

Communication Problems

Autistic patients feel much difficulty in communicating with others. It might be due to the abnormal speech development that is seen in more than one-third of autism patients. The communication problems are present in autism patients since infancy. 

The signs of poor communication in the infancy may include the following; 

• Decreased responsiveness
• Delayed onset of babbling
• Unsynchronized vocal patterns
• Unusual gestures

These symptoms progress with age with the following signs being found in the second and third years of life; 

• Less integrated gestures
• Less frequent babbling
• Less diversity in words or consonants
• Less diverse word combinations

These patients fail to point at different objects. They cannot make requests to others. They also fail to share experience or comment on different objects. 

One distinct feature is that such patients tend to look at the pointed hand instead of looking at the pointed object. 

These patients can perform better in simple language tasks like vocabulary and spelling but fail at complex tasks like comprehension and inference. People often fail to understand that their audience is unable to comprehend them when they talk to autistic patients. 

Restricted Behavior

Autism also causes abnormal behavioral development in children. Studies have shown that autistic individuals can show the following restricted or repetitive behaviors.  

Stereotyped Behavior

This behavior is characterized by repetitive movements of some body parts, mostly extremities. Examples include head rolling and hand flopping, etc. 

Compulsive Behavior

These behaviors are adapted by individuals to reduce anxiety. The time-consuming activities are performed repeatedly by such individuals. They feel some compulsion to perform these activities or to do things according to some strict rules. Examples include washing hands repeatedly, placing things in a specific order, etc. 

This behavior is a characteristic of another disease called OCD. 

Ritualistic Behavior

This behavior is characterized by having one constant ritual for daily life activities. For example, these individuals always wear the same type of clothes all the time, always have the same menu for food, etc. 

Autistic patients are resistant to any changes. It is called sameness. The sameness and ritualistic behavior in autistic individuals are thought to be related to each other. 

Restricted Interests

Autistic individuals have restricted interests. They have a preoccupation with a single thing such as a toy or TV programs, etc. 

Behavior of Self-injury

Autistic individuals also display a mild behavior of self-injury. They are often seen doing hand biting, eye-poking, head-banging, and related activities. 

Unusual Abilities 

As stated earlier, some autistic individuals have unusual abilities in some aspects of life. They perform well than normal children in some areas. It has been found that around 10% of individuals with autism have unusual abilities like memorizing trivia, etc. they have better abilities of perception and attention than the general population. 

Autistic savants are people who have mental disabilities but perform more than average in some instances. They have one specific skill far better than the average human beings. Most of the autistic savant skills are related to a specific type of memory. 

Sensory and Motor Abnormalities

Sensory and motor abnormalities are also seen in some autistic persons. Sensory symptoms are of varying nature. 

Around 60 to 80% of autistic individuals have poor muscle tone and toe walking. They have poor motor planning and motor coordination. 

Other Symptoms

Stress is also seen in some autism patients. 

Gastrointestinal disturbances are very common in autistic individuals. 

Around one-third of the autism patients also have some abnormal eating behaviors.

Causes 

Autism is caused by several genetic as well as environmental factors. Earlier, it was thought there must be one common cause for various clinical features seen in patients with autism. However, it is now known that several complex factors can contribute to autism in these patients.

The major factors that can cause autism are as follows. 

Genetic Factors

Autism is a heritable disease having a strong genetic basis. The genetics of autism is complex due to interaction among the genetic as well as environmental factors. Several epigenetic factors are also involved in causing autism. The epigenetic factors do not result in changes in DNA sequencing but can change gene expression and are also heritable. 

Gene sequencing has revealed that many genes are associated with autism in one way or another. 

Autism has high heritability among twins. Moreover, siblings of autism patients are more likely to have autism. 

No single mutation has been attributed to autism so far. Studies have revealed that mutations causing autism can not be classified as single-gene mutations or Mendelian mutations. Rather, several different genes have been identified with minor mutations having different roles in autism. 

Autism is more commonly seen in males as compared to females. Several genetic theories like X-linkage have been used to describe the higher occurrence among males. 

Maternal Causes

Certain maternal disease conditions during pregnancy can also cause autism. The fetal neurodevelopment is influenced by the status of maternal nutrition during pregnancy as well as in pre-conception stages. Proper maternal nutrition is essential for the normal neurodevelopment of the fetus. 

Maternal inflammation during pregnancy can limit the development of the nervous system in the fetus and can cause autism. 

Autoimmune diseases of the mother can also limit neurodevelopment and make the baby susceptible to autism. 

Intrauterine growth restriction is also seen to be a cause of autism. 

Risk factors

Certain risk factors during pregnancy can increase the risk of autism in the developing baby. Certain environmental pollutants are known as risk factors for autism. 

Exposure of the mother to the following environmental toxins during pregnancy can put the baby at risk of autism. 

• Alcohol
• Smoking 
• Illicit drugs
• Plastic products
• Phenols
• Pesticides

Pathophysiology

The pathophysiology of autism is also complex as it is a behavior related to diseases. However, certain theories describe the following pathophysiology of the diseases. 

It has been found that the cerebral cortex is affected in individuals with autism. Neuroimaging of the brain has indicated that the prefrontal and temporal areas of the brain are more affected in autism. The abnormalities in the prefrontal cortex can explain the behavioral symptoms of autism.  

The cerebellum of autistic persons is also found to be affected. The brain scans of these patients show cerebellar hypoplasia, loss of Purkinje neurons, and loss of granule cells found in the cerebellum. The cerebellar changes are responsible for motor abnormalities found in autism patients. 

Neurochemical abnormalities have also been found in autism. These include changes in the levels of dopamine, serotonin and catecholamine neurotransmitters. 

Synaptic dysfunction has also been found in autism patients. Different mutations can cause autism by causes disruption of some synaptic pathways. 

Classification

As mentioned earlier, autism is one of the five major pervasive developmental disorders (PDD). While discussing the classification of autism, it is classified into classic autism, Asperger syndrome, and atypical autism. 

Classic Autism

It is also called an autism disorder. It is a prototype of pervasive developmental disorders. Communication abnormalities, defective social behavior, and repetitive restricted behaviors are seen in this type. In this article, we have mostly discussed classic autism. 

Asperger Syndrome

It has less severe symptoms as compared to classic autism. Social and behavioral problems are present. However, such patients may have no language problems and may also have intact intellectual abilities. 

These patients can have problems in understanding certain language components such as humor etc. 

Atypical Autism

It is also called pervasive developmental disorder – not otherwise specified (PDD-NOS). The patients have some symptoms of classic autism as well as Asperger syndrome. But the symptoms are not enough to diagnose these conditions. Social and communication problems may also be present. 

Asperger syndrome and atypical autism are collectively called autism spectrum disorders.  

In addition to these, autism is also classified into syndromal and non-syndromal subtypes. Syndromal autism is characterized by a more severe intellectual disability. 

Autism Spectrum

Autism is a disorder that covers a wide spectrum of symptoms. It ranges from severely impaired patients to some highly functioning patients. 

The spectrum ranges from completely silent, developmentally disabled individuals to high functioning individuals that have intact intellect. However, high functioning individuals also have some odd or strange social behavior. 

Because of the broad spectrum of the diseases, the boundaries between the different stages or categories of the disease are arbitrary. Some divided this disorder into three categories; high-functioning, mid-functioning, and low-functioning autism (LFA, MFA, and HFA). This classification is based on the IQ of autistic individuals.

Screening

Parents notice the signs of autism in their children during the first two years of life. The following developmental milestones are checked to assess the children for autism screening. Inability to meet any of these milestones in an indication that the individual may have autism. 

• No response to name or eye-contact by 6 months
• No babbling in the baby till 12 months
• No gestures expressed by the baby in the first 12 months
• No word is spoken by the baby in 16 months
• No two words or phrases are spoken by 24 months
• Loss of language or social skills at any stage of life

If any of these signs are seen, further evaluation is needed to formulate a diagnosis. It is advised that all children must be screened for autism at 18 and 24 months of age. 

Diagnosis

Although there are no specific tests for the diagnosis of autism, the following assessments may be performed. 

• Speech and Language assessment
• Psychological and Psychiatric Evaluation
• Chromosomal analysis can also be performed if indicated
• EEG
• Neuroimaging
• Positron Emission Tomography (PET SCAN)

All these evaluation criteria help in establishing the diagnosis of autism. However, autism may also be confused with other conditions like mental retardation, Rett syndrome, schizophrenia, and autism spectrum disorders. 

Management

The main goal in autism management is to reduce the deficits in individuals to improve the quality of life as well as alleviate the distress of other family members. Educational, as well as medicinal therapies, are adapted for the management of autism patients. 

Educational therapies include speech therapy, skill development therapy, behavioral analysis, and occupational therapy. 

Medical intervention includes drugs to treat anxiety and distress. These include antidepressants, psychoactive and anticonvulsant drugs. 

Summary

Autism is a developmental disorder of the brain characterized by impaired social behavior, communication problems as well as repetitive restricted behavior. 

The signs are first noted by the parents in the first two to three years of life. 

The patients have abnormal social development. They smile less often and usually do not make eye contact. They are unable to understand and express themselves socially. They are also unable to understand expressions or express their emotions. 

They have defective speech and language development. Because of this reason, they face communication problems. They are unable to engage in complex language tasks such as comprehension and inference. They also fail to make friends and keep friendships because they are not social. Although they prefer loneliness, they also often feel alone. 

They often develop repetitive restricted behavior like compulsive behavior, sameness, the behavior of self-injury, etc. 

Autistic individuals can also have some extra normal abilities such as autistic savants. 

Motor abnormalities are also seen in most of the autistic individuals.

Autism is caused by several genetic as well as environmental factors. 

No single gene has been associated with autism as it is thought to be caused by complex inheritance involving multiple genes. 

Maternal diseases such as inflammation or autoimmune diseases can also cause autism. 

Exposure to environmental toxins during pregnancy can also increase the risk of autism.

Pathophysiology of the disease involves damages to the cerebral cortex, cerebellum, and abnormal levels of different neurotransmitters.

Autism can be classified into classical autism, Asperger syndrome, and atypical autism; the latter two are collectively called Autism Spectrum Disorder (ASD). 

Syndromal and non-syndromal are also two types of autism. 

The screening involves checking different development milestones at 18 to 24 months of age. 

Different evaluations are performed before making a diagnosis of autism. 

Management of autism patients includes educational as well as medical interventions.

References

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