Autism – Symptoms, Causes, Diagnosis and Treatment

Editor's Note: This article has been recently updated with latest information and research studies.


Autism refers to a group of neurodevelopmental disorders called autism spectrum disorders (ASDs). For the sake of this article, we will be referring to all ASDs using the term autism. The disorder is a result of brain abnormalities that happens early in a child’s development and it is characterized by repetitive and unusual behavior as well as difficulties with communication and social interaction. But the hallmark of all autism disorders is noticeable problems with all forms of social interaction. The symptoms of autism occur very early in childhood and they can be severe enough to affect a person’s ability to function on their own once they become adults. There is currently no cure* for autism but therapies and remedies help improve* symptoms and outcomes. Researchers are also working hard on finding the underlying causes of autism in order to prevent children from being affected in the future.

The term spectrum in ASD is used to refer to the wide range of symptoms, skills, and levels of disability that occur in people with this complex developmental disorder. The Diagnostic and Statistical Manual of Mental Disorders list childhood disintegrative disorder, Asperger syndrome, and pervasive developmental disorders not otherwise specified as autism disorders rather than separate disorders. Autism has been on the rise in the past three decades but is beginning to reach a plateau in some developed countries. Although the disorder occurs in every racial and ethnic group, epidemiological studies did note that some groups are more affected than others. The CDC states that autism is about 4.5 times more likely to occur in boys than girls, and the worldwide prevalence is estimated to be around 62 in every 10 000 people.

The exact causes of autism remain unknown but researchers believe that genetic and environmental factors may play a role. Genetic factors include gene mutations but these are not limited to single genes. Among environmental factors, some proposed causes have led to widespread controversies. The most notable one was the vaccine hypothesis that started in 1998 with the publishing of a fraudulent research paper in The Lancet. This hypothesis has long been refuted but the belief that vaccines cause autism still persists leading to lower vaccination rates and outbreaks of mumps, rubella, and measles. One of the largest and latest studies to debunk the vaccine-autism link was published in a 2015 issue of JAMA and that stated that there is no evidence that vaccines cause autism.

Parents who are told by professionals that their child is affected with autism often feel devastated. It is important that parents get social support that will make it possible for them to work with clinicians in order to improve* their child’s outcomes. Although the diagnosis of autism can sound like a death sentence, truth is that up to 25% of children with autism who receive early intervention are no longer considered to be in the autism spectrum. What this means is that there is hope that a child can reach its fullest potential if given the right tools. This article explains more about autism, the signs, the possible causes, how it is diagnosed, and how it is treated. Make sure to learn as much as you can about autism if you are a parent or are taking care of someone afflicted with this disorder.

Signs and Symptoms

Autism can manifest as a wide variety of symptoms that can occur in early infancy to any time before two years of age. Autism always starts very early in childhood but parents may not recognize symptoms early on, especially with milder cases of autism. Children with autism may show severe impairment in some areas of functioning such as speech and social interaction and normal and even superior in others such as art and map learning. The most basic thing to look for when suspecting that a child may have autism is if they seem different when compared to other children their own age. For instance, if a 6-month old does not seem to make eye contact with a parent or smile, it could mean that the child is afflicted with autism. Knowing these subtle signs of autism is important to make early intervention possible. In general, autism is characterized by the following symptoms:

  • Social Impairment
  • Cognitive Impairment
  • Communication Problems
  • Repetitive Behavior

These symptoms can range from mild to severe given that autism is, after all, a spectrum disorder. In many cases, parents may notice symptoms before 6 months of age and these symptoms become even more noticeable as a child grows. In other cases, a child may develop at a pace considered normal for their age but begin showing unusual symptoms and even regress, i.e. lose* the skills they have developed earlier in their childhood. If you suspect that the symptoms your child is showing is autism, consider taking a look at the more specific symptoms as provided by the NHS to see if there is any reason for concern. Here is a list of the more specific symptoms to look out for.

Signs and Symptoms Of Autism In Pre-School Children

Language Problems

  • Delayed speech development (a child may start speaking at a later age than what is normal or have a poor vocabulary for one’s age)
  • Repeating the same words and phrases over and over again
  • Monotonous or flat speech
  • Speaking in single words although being able to speak in full sentences

Responding To Other People

  • Not responding when their name is called or when they’re asked a question
  • Rejecting affection even when sometimes initiating affection themselves
  • Reacting unusually negatively when asked to do something by someone else

Social Interaction Problems

  • Unaware of other people’s personal space or intolerant when someone enters their own personal space
  • Showing no interest in interacting with peers or adults
  • Seem like they don’t enjoy activities that children that other children enjoy
  • Prefers playing alone to playing with others
  • Does not use gestures and shows little facial expressions when speaking
  • Avoids making eye contact

Behavioral Problems

  • Prone to making repetitive movements like hand clapping or rocking back and forth
  • Playing with toys in repetitive ways such as lining things in size and color
  • Likes having a routine and becoming very upset when routine is disrupted
  • Showing strong like or dislike of food depending on color, taste, and texture
  • Showing unusual sensory interests (sniffing objects)

Signs And Symptoms Of Autism In School-Age Children

Language Problems

  • Avoids speaking in most situations
  • Monotonous or flat-sounding speech
  • Seeming unable to be creative with language but using pre-learned phrases instead
  • Unable to form two-way conversations

Responding To Other People

  • Understanding everything said in a literal way
  • Reacting negatively when being told to do something

Social Interaction Problems

  • Unaware of of other people’s personal space and not liking when someone enters their own personal space
  • Shows no interest in interacting with peers or other people and has problems forming friendships
  • Does not understand how to react in social situations, example when to greet someone.
  • Unable to form the tone and content of their speech in a manner deemed appropriate for the situation
  • Not enjoying situations and activities that most children of their age enjoy
  • Rarely using gestures or facial expressions when communicating
  • Avoiding eye contact

Behavioral Problems

  • Repetitive movement like hand clapping or rocking back and forth
  • Playing in a repetitive and unimaginative way, usually alone
  • Showing a high interest in a peculiar and often narrow area or subject
  • Likes having a daily routine and dislikes when the routine is in any way changed or disrupted
  • Prefers specific foods with a certain taste, color, or texture

Although these are the usual signs and symptoms associated with autism, children and adults afflicted with this disorder will often show a range of other symptoms as well. These are usually a result of comorbid conditions that are common with autism. For instance, children with autism may have learning difficulties, epilepsy, OCD, anxiety, depression, sleep disturbances, and hyperactivity among many other things. The symptoms of these comorbid conditions are treated separately if they are severe enough to disrupt a child’s well-being and development. Treatment may involve taking medication, especially in cases of epilepsy and anxiety.

Doctors will also focus on symptoms and look for behavioral abnormalities when diagnosing autism or to rule out other conditions. Some developmental disorders or even purely physical conditions such as hearing impairment may mimic autism. For instance, a baby that does not respond to mom’s voice or to their name may have a hearing problem and not necessarily autism. Similarly, developmental disorders can also look like autism.

Causes of Autism

The exact causes of autism are not completely understood. However, research has found several risk factors and possible culprits. A review published in Frontiers in Molecular Neuroscience states that there’s plenty of scientific evidence that autism has a strong genetic component to it. For instance, one of the strongest arguments for this theory is that monozygotic twins have a 90% chance to be both affected by autism in comparison with dizygotic twins who have only a 10% chance of both being affected. Furthermore, a study published in a 2004 issue of Pediatrics, siblings of children with autism have a 2-8% chance of having the disorder themselves. Another thing to note is that autism affects males more often than females suggesting that sex chromosomes may also play a role in autism. Scientists have so far isolated several genetic mutations linked to autism. But despite such findings, it is not clear which genes exactly are responsible for autism.

The genetic factors linked to autism are believed to cause abnormal development of the brain which causes the symptoms associated with the disorder. Children with autism show atypical brain development. Generally, children with autism may show abnormal brain growth and an increased brain volume through life. Studies also found differences in the ways the neurons connect in the brain of people with autism. But autism is a very complex disorder that affects many different areas of a person’s health and functioning and the severity of the symptoms varies from relatively mild to debilitating.

Researchers state that the heterogeneous nature of this disorder is the main reason why finding the exact cause is difficult.

As far as environmental factors are concerned, researchers believe that they may have a strong impact on a person’s risk of autism and its severity. “Environmental factors” is a term that refers to outside factors that can have an effect on any organism’s health. According to a recent review published in Molecular Autism, evidence shows that vaccines, smoking, in vitro fertilization, and surrogacy are not linked to autism. On the other hand, advanced parental age, birth complications such as ischemia and trauma, maternal obesity, diabetes, and caesarian section have shown a link to autism to a greater or lesser extent. As far a nutrition goes, most reviews are inconclusive but suggest a possible link with Vitamin D, folic acid, and omega-3 fatty acid deficiencies. Toxic elements such as lead and mercury were less studied for their role on autism but there may be a strong link, especially with high doses and chronic exposure. Chronic exposure to environmental toxins may affect a child’s development by altering genes, causing oxidative stress, inflammation, endocrine disruption, and neurotransmitter functioning among many other things.

For quite some time now, there has been a debate that vaccines may be strongly linked to autism. The public outrage started with the publication of a research paper in a 1998 issue of The Lancet by Andrew Wakefield and colleagues. The study described the case of 8 children that developed the first symptoms of autism one month after receiving immunization. However, researchers stated that the study lacked objectivity because there were no control subjects and the study excluded vaccinated children that did not develop autism. Another shortcoming of this study is that the symptoms preceding the onset of autism in these children could not be explained by vaccination alone, i.e. there was no evidence that vaccines caused these symptoms. Jeffrey S. Gerber and Paul A. Offit have explained in an article published in Clinical Infectious Diseases that ethylmercury-containing preservative found in some vaccines is believed to be toxic to the central nervous system. However, this preservative is found in insignificant doses in vaccines and animal and human studies have long tested their safety at even higher doses than the ones found in most vaccines and all studies deemed this compound safe. However, the fear that vaccines may have caused autism in a child is understandable given that autism develops at the same time a child is vaccinated but the obvious lack of evidence to support this claim means that this link is purely coincidental.

Diagnosing Autism

When a parent suspects that their child may be showing developmental delay or behavior not typical for their child or the child’s age, they should speak to their child’s doctor if there is any reason for concern. They may then give you The Modified Checklist of Autism in Toddlers (M-CHAT) which is a list of informative questions about your child which the doctor will use to see if there is reason to refer your child to a specialist. If autism is suspected, a specially-trained physician and child psychologist will perform behavioral tests. The child may also be referred to hearing and lead exposure tests as well as developmental evaluations.

Early diagnosis of autism is a controversial subject given that children reach developmental milestones at a different pace. However, early diagnosis is important because the earlier a child starts treatment, the better the outcomes. Since most cases of autism start before 2 years of age, this is the time a diagnosis should be established. Trained clinicians will evaluate a child based on the child’s behavioral characteristics. Specifically, they will look for problems in communication, socializing, and repetitive behavior. The diagnosis is usually performed in two steps: developmental screening during well-child checkups and a more comprehensive evaluation by a team of clinicians.

Most physicians will notice problems in a child during regular checkups. However, some physicians may not be well-trained in the area of autism disorders and may miss subtler symptoms. If you do have concerns regarding your child, do ask your pediatrician to perform a developmental-screening test. Parents often know their child best and physicians should take their concerns seriously. If your physician is dismissive, ask for a second opinion. Screening instruments used for quick evaluation include:

  • Checklist of Autism in Toddlers (CHAT)
  • The modified Checklist for Autism in Toddlers (M-CHAT)
  • 11 the Screening Tool for Autism in Two-Year-Olds (STAT)
  • The Social Communication Questionnaire (SCQ)

These instruments are not enough to provide an individual diagnosis but rather to help determine if there is a need for further screening. While these screening tools are helpful in diagnosing severe and moderate cases of autism, they are not helpful in diagnosing mild cases of autism such as high-functioning autism or Asperger’s syndrome. Instead, mild cases of autism are usually first detected in school-aged children using the following tools:

  • The Autism Spectrum Screening Questionnaire (ASSQ)
  • 14 the Australian Scale for Asperger’s Syndrome
  • The Childhood Asperger Syndrome Test (CAST)

Children with high-functioning autism or Asperger’s usually don’t show the classical symptoms associated with autism such as language delay. This is why the screening tools for such cases focus on social and behavioral impairments as these are the hallmarks of high-functioning autism.

Once the above-mentioned screening tools prove that there is reason enough to suspect autism in a child, the next step is to refer the child to comprehensive evaluation. A team of clinicians that includes psychologists, neurologists, speech therapist, psychiatrist, and other clinicians specialized in diagnosing autism. The goal of this step is to rule out other developmental disorders or finally establish a diagnosis of autism. Given that autism is a complex, heterogenous disorder, comprehensive evaluation is needed. Doctors will perform a neurologic or genetic testing alongside the assessment of cognitive and language skills. Later on, testing designed specifically for diagnosing autism may be included and they involve:

  • Autism Diagnosis Interview-Revised (ADI-R)17 – A structured interview with over 100 questions that is performed with the caregiver present. The aim of this test is to evaluate the child’s communication skills, social interaction, the presence of repetitive behavior, and to determine when the first symptoms started.
  • Autism Diagnostic Observation Schedule (ADOS-G) – An observational measure tool used to determine the social and communication behaviors that are in some way delayed, absent or abnormal.
  • Childhood Autism Rating Scale (CARS) – Used in evaluating a child’s motor skills which are often affected. The tool also helps look for adaptation to change, listening ability, verbal responsiveness, and general relating to other people. The great thing about this test is that it is suitable for children over 2 years of age. The examiner will ask the parents questions regarding the child’s behavior while observing the child. Then, they will rate the child using a scale by observing deviation from behavior considered normal for a child’s age.

Other than the screening tools designed specifically for diagnosing autism, other tests may also be performed. Hearing tests are common when a doctor suspects that a child may have autism. The reason being that one of the first noticeable symptoms of autism is not reacting to sound, including when the child’s name is being called. Doctors will also perform a lead test, especially if a child is in that stage of development when they put things in their mouth. This is because elevated lead levels are often found in children with autism.

The goal of individualized evaluation is to detriment a child’s specific case. No case of autism is alike and doctors will help detriment the child’s strengths and weaknesses. The evaluation team will inform the parents about their diagnosis and parents will have the opportunity to ask any questions regarding their child. Parents are given guidelines on what to do next. Establishing a correct diagnosis is the first step towards treatment.

Treatment and Therapies

There are currently no treatment options for autism but therapies help manage symptoms and maximize a child’s abilities. Children with autism need a personalized approach to reach their fullest potential and studies show that the earlier the intervention, the better the outcomes. Therapy is usually individually tailored and parents are often involved. Examples of therapy for children with autism include:

Behavioral Management Therapy – The aim of such therapies is to reduce* unwanted behavior and support wanted behavior. There are different approaches to achieve this. These therapies help the child develop necessary social and language skills. For example, pivotal response training teaches the child to become motivated to initiate conversation. Some of these therapies can be done by the parents in their home and some may require a specialist.

Cognitive behavioral therapy (CBT) – The goal of CBT is always to help a person recognize the link between thoughts, emotions, and behavior. A specialized form of CBT for children and adults with certain types of autism can help them learn better coping skills. CBT can also help patients with autism deal with depression, anxiety, and other common comorbid conditions.

Early intervention – With early intervention, between 3 – 25% of children diagnosed with autism are no longer on the autism spectrum once they get older. The goal of early intervention is to help children develop critical skills such as social skills, thinking skills, and communication skills among many other things.

Joint attention therapy – Children with autism often have trouble with what is known as joint attention. Joint attention is when you’re able to determine what someone else is looking at or look where someone is pointing their finger at.

Nutritional therapy – Children with autism are often fussy eaters. They may avoid certain foods because they don’t like the taste or because they don’t like the texture of the food. As a result, children with autism may be at risk of developing nutritional deficiencies. A nutritionist and dietitian can help parents develop a eating plan that will support their child’s development.

Physical therapy – Physical therapy helps children with autism build strength, posture, and balance. Children with autism often develop problems with movement and coordination so physical therapy may be helpful in such cases.

Speech-language therapy – This form of therapy helps children learn to name things and people correctly. Therapy may also involve helping the child express feelings and needs as well as tone and rate of speech. This form of therapy also helps with non-verbal communication skills which are just as important in mastering social skills in general.

These are just a few examples of therapies for children and adults with autism. As already explained, therapy should be individually tailored based on specific symptoms. Not all children with autism show the same strengths and weaknesses, but almost all have trouble with communication and socializing. Your doctor will tell you which treatment should work best for your child. For school-aged children, there are special programs that will help your child learn with least difficulty. Your child may also be prescribed medication to help with symptoms like seizures or depression. But otherwise, there is no medication to treat* autism-specific symptoms.

Besides conventional therapy, some parents may turn to complementary and alternative medicine in the hopes of helping their child. Such therapies may involve special diets, chelation, and even animal therapy. While some may work, others were found to be even potentially harmful. Studies speak mostly in favor of therapies deemed safe for most people, including those afflicted with autism. For example, animal therapy is fun and safe for children with autism and it helps with bonding. Music therapy can also be considered safe if the child shows an appreciation for such an intervention. But with dietary and supplement interventions, parents are often advised to be cautious as these therapies may do more harm than good.

Savant Syndrome

Children with autism have trouble interacting with the outside world. But that doesn’t mean that they don’t have a rich inner world. In fact, the great number of autistic savants in the world demonstrate how rich and imaginative the inner world of an autistic person can be. But social and communication problems make it difficult, and in some cases impossible to communicate what is going on in the mind of a person suffering from autism. According to autism.org, some people with autism state that the world feels overwhelming to them and that this creates great anxiety. This may explain why some children and adults with autism feel great frustration when there is too much stimulus or change in their world. Unfortunately, we know very little about autism and are unable to say much about this condition.

One thing that has drawn great attention is savant syndrome which is often observed in children with autism. Savant syndrome is a rare phenomenon with a long history. The first recorded case was that of Jedediah Buxton in 1783. Jedediah had extraordinary math skills and memory but considered intellectually disabled in other skills. Today, we know that 1 in 10 children with autism show some extraordinary abilities, however these numbers are just rough estimates. Also, 10-50% of children with autism are believed to be savants in some way or another. Children and adults with savant syndrome usually excel in some of the following skills: music playing, art, calendar calculating, math, spatial learning, and having outstanding knowledge of a field of study such as geography and similar. Although numerous cases of savant syndrome have been recorder throughout history, researchers are still baffled by this phenomenon. There are some theories providing possible explanations for savants.

One theory is that damage to the left hemisphere of the brain that can happen in autism disorders leads to overcompensation in the right hemisphere. This might explain why savants are able to develop almost genius skills in a narrow field of their interest. Other theories focus on memory. Memory seems to be an integral component of savant syndrome and most children and adults showing these kinds of abilities usually have them due to their unique memory abilities. Memory often works together with intelligence but it may also work separately in the cases of savants. Autistic people often score low on the conventional intelligence test so they’re often labeled as intellectually disabled. But despite seemingly strong problems with thinking and learning, people with autism will have incredible memory.


Autism is a complex disorder occurring in a spectrum of a wide range of symptoms. While some children with autism may have only mild symptoms, other may have difficulty learning to speak, take care of themselves, and interact with others. In all cases, early intervention is important to improve* a person’s outcomes. The reason being that most skills and brain connections are made early in childhood. However, early intervention is often impossible in mild cases of autism where the first symptoms are usually noticeable around school age.

The symptoms of autism are varied but all can be found in areas that have to do with communication and socializing. The hallmarks of autism are an inability to interact and communicate with others in a normal way. This also means that people with this condition may not be able to learn the skills necessary for functioning in everyday life. However, in many cases, children with autism are able to develop in full-functioning adults.

The causes of autism are not well understood and research has linked both genetic and environmental factors to the disorder. Autism is a heritable condition caused by certain gene mutations. But some environmental factors may likely play a role in the risk and severity of autism. Among environmental factors, research has excluded vaccines which were a controversial subject for a very long time. Although vaccines contain preservatives that would likely be toxic to the brain at very high doses, they are present in vaccines in miniscule amounts. But factors that may lead to autism include a mother’s age, diabetes, and other medical conditions. Environmental toxins such as lead and mercury may also lead to developmental problems if children are exposed to these chemicals in high doses before or shortly after birth.

Diagnosing autism is a tricky process. Most of the times, you will hear that diagnosing a child with a developmental problem at an early age may be misleading. The reason being that not all children develop at the same rate. However, the case is different with autism. The first symptoms of some cases of autism are usually noticeable early in life. Most children will be showing symptoms like delayed speech and a lack of eye contact by 3 years of age.

Some children may begin developing normally and later regress and lose* the skills they have previously acquired. If a parent or pediatrician suspects autism, the child may be referred to a specialist who will determine if there is reason for concern. If the specialist believes that the symptoms a child is experiencing could possibly mean autism, they will refer the child to further testing to establish a final diagnosis. This is usually a process that takes some time and which involves the parents as well. Once a diagnosis is established, parents will be offered advice and therapy for the child.

As far as treatment goes, there is unfortunately no cure* for autism. But therapies that focus on the symptoms help children learn critical skills and develop ways to cope. The earlier therapy starts, the better the outcomes for the child. Children may learn how to communicate effectively, how to understand their own thoughts and emotions, and how to bond with other people. Other than conventional therapy, some parents may also try alternative and complementary therapies. A popular example is animal therapy where children are given a chance to interact with animals like horses and dolphins. These therapies are generally considered safe and helpful when it comes to learning ways to bond with others. As far as nutritional approaches go, it’s best to speak to a nutritionist before considering any alternative like dairy and gluten-free diets. These may not be necessary or helpful to children with autism and may be potentially harmful.

Autism is a complex disorder that research is only beginning to understand. The disorder starts with abnormal brain development but why this happens is not fully understood. But autism is also not like other intellectual disabilities. The disorder also has unique features and some children affected may show remarkable talents and abilities. This is known as savant syndrome which is often seen in children with autism. Savants are people with intellectual disabilities but who also show near-genius skills in areas like math and music. Researchers have studies savants with the hopes of gaining more insight into autism and how unique the brains of children with this condition are. Although savants are not well understood just, some theories suggest that overcompensation in certain brain areas and above-average memory may explain savant syndrome.

Parents who suspect that their child is not developing normally will often feel heartbroken once a diagnosis of autism is established. Although this is understandable, parents should know that they are not alone. Autism has been increasing* in the past several decades and many people were found to face the same challenges. Luckily, social support and treatment options are available to people and families afflicted with autism. Although autism does set some challenges, there are ways you and your child can overcome these challenges. Always ask professionals for advice and continue learning about autism in order to give your child or other family member the best support possible.


  • https://www.cdc.gov/ncbddd/autism/data.html
  • http://nationalautismassociation.org/resources/signs-of-autism/
  • http://www.nhs.uk/Conditions/Autistic-spectrum-disorder/Pages/Symptoms.aspx
  • http://pediatrics.aappublications.org/content/113/5/e472
  • http://www.autism.org.uk/about/what-is/asd.aspx