The symptoms of the autistic spectrum disorder ASD

Disclaimer: Any information provided in this article is not meant to diagnose or treat. It should not replace the consultation with a professional qualified to deal with the autistic spectrum disorder (ASD).

Common Symptoms and Signs of Autism

The first symptoms (or hints) of autism in children can be traced in the very first months of life (at least in some cases). However, the large majority of children with DSM-2 autism can be diagnosed at around 18-24 months. Some diagnosis comes later in life, and the disorder is sometimes confused with other mental issues (especially DSM-1 autism).

Of course, DSM-3 autism (the most severe) is relatively easier to assess than DSM-1 (high functioning), therefore some individuals may reach adulthood undiagnosed (or discover later in life that autism is the root cause of the difficulties experienced throughout life).

Let’s now explain the symptoms of autism for toddlers, children in pre-schooling/schooling age, and adults.

Signs of autism for toddlers (1-36 months)

Signs of autism in toddlers

Parents, tutors, caregivers should pay great attention, in the first 36 months after birth, on the possible presence of any of the following common symptoms and signs of autism for young children and get expert advice in case of doubts:

  • The child escapes eye contact with parents and/or other people, and does not look at things when others point at them
  • The child prefers solitude to company and has little joyful expressions if any
  • The child seems uninterested in cuddles and interaction with others (lack of empathy and reading other people’s feelings via gestures, facial expressions, or tone of voice)
  • The child has an obsessive interest for a few topics and stimulus, accompanied by a total lack of interest for others
  • The child expresses repetitive behavior, and in some cases self-destructive attitudes (compulsive movement of the hands, phrases repeated over and over, rocking back, and forth, flapping, spinning, banging the head or the arms against walls and furniture, starring at the washing machine, flipping levers up and down without pause, etc.)
  • The child shows hyper attention to sounds, touches, smells, or sights
  • The child has clear communication issues, both verbal and non-verbal; talking is monotone, flat, without emotions, at times the same sentences are repeated over and over (echolalia)
  • The child feels uncomfortable with anything different from the few known routines (e.g. daily schedule, meal, clothes, the route to school or hospital)
  • The child experiences epilepsy or seizure episodes
  • The child has little or no back-and-forth gestures such as pointing, showing, reaching or waving
  • The child shows ritualistic behaviors (e.g. lines up objects, touches objects over and over in a specific order)
  • The range of interests of the child is very restricted and monothematic

The intensity of these signs depends on the type of autism of the child: from the Asperger’s syndrome (a condition close to autism, but characterized by higher functioning levels, proper verbal skills, average/above average IQ), up to the disintegrative disorders (or low functioning autism, where children lack social and communication skills completely after the age of 2 or 3).

It is important to note, though, that some of the signs listed above may be shown by children without autism. Only specialized doctors can assess if behavioral and social deficiencies are related to the autism spectrum disorder, or to other pathologies, and their level of severity.

Signs and symptoms of autism for children in pre-schooling age (3 to 5 years)

For some children, the signs of autism might not become completely clear until they reach the age of preschool (or even a bit later, i.e. when they go to school).

This is the case of children that show mild symptoms up to approximately three years, but start experiencing noticeable development gaps compared to the children of their age quickly right after (learning difficulties, communication issues, the tendency to isolation, and the other common traits of the autism spectrum).

Signs of autism in pre-school kids (up to 5 years)

In these cases, the development gap becomes more and more evident day after day: in these circumstances, parents are advised to seek professional consultation (is autism the cause?).

The behavioral red flags of the autistic syndrome in this stage are:

  • Repetitive and compulsive movements, like flapping, prolonged rocking or spinning of objects, starring at moving devices and objects
  • Obsessive interest for specific toys or objects (and total indifference to all others)
  • Strong resistance to change in routines and environment, with uncontrolled negative reactions for any little change
  • Severe distress in case of unknown sounds, and agoraphobia (strong anxiety in public places)
  • Resistance to eat specific foods, especially solid ones
  • Issues at the toilette
  • Chronic sleep disorders or difficulties

The social red flags of the autistic spectrum disorder in this stage are:

  • The child is extremely reserved and does not socialize with school mates and teachers
  • Eye contact with peers, parents, and teachers is missing
  • Verbal issues start to appear, like grammatical errors, poorly constructed sentences, or obsession with specific words repeated over and over
  • Lack of social skills, interaction with others (even rejecting cuddles)
  • Solitary behavior is preferred to be playing and sharing experiences with others
  • The child never cries or cries all the time

Signs and symptoms of autism for children in school-age (5 to 10 years)

In the past, a large proportion of children got an ASD diagnosis only when hitting the school age, and ASD was often confused with other psychiatric diseases. Thanks to the autism awareness campaigns, children have better chances today to get a clearer diagnosis earlier in life (and initiate beneficial therapies).

Autistic symptoms at school age

The typical symptoms of autism for children in schooling age are:

  • Conversational issues with peers (single topic obsession, or tendency to have flat monologues without attention to the comments of others)
  • Inability to understand non-verbal communication, and tendency to take things literally (not understanding jokes and metaphors)
  • Monotonous tone of voice or unusual way of talking
  • Preference for solitude, distress for social gatherings, lack of friends
  • Strictness in following the rules, either in school and in games or any sort (including sport)
  • Social awkwardness
  • Unusual interests and obsessions, with a total lack of interest for different subjects
  • Unusual physical movements, such as biting, touching, rocking or finger flicking
  • Compulsive use of the senses like smell, touch, taste, hearing, and vision
  • Anxiety in case of changes in routines and people
  • Passive-aggressive behavior
  • Anxiety when dealing with any new circumstance, especially entering the teenager age
  • Expressing behavior that does not comply with socially accepted standards

Signs and symptoms of autism for adults

Adults with autism show similar symptoms like the ones listed above for the other age groups. However, while some people with mild autism become able to cope with their difficulties while moving from childhood to adulthood, finding somehow an acceptable balance, others spend their lives in isolation and frustration (sometimes unable to give a precise name to their condition).

Autism signs and symptoms in adults

Adults that recognize autism symptoms shall seek medical advice: a diagnosis may be challenging to accept but can be also liberating from another perspective. Many adults affirmed that an autism diagnosis brought a sense of clarity and relief, and set them on a new personal development path (ad hoc therapies, connection with other adults suffering the same condition, etc). Of course, all this is true for mild autism levels only.

Autistic vs. Normal Child Development

A non-autistic child shall show the following typical development path in the first 36 months from birth (any significant deviation can be considered a red flag for autism and double-checked):

Within 12 months:

  • The child looks at faces intently, responding to other people’s emotion with appropriate reactions
  • Smiles imitates some facial expressions, follows moving objects with a movement of the eyes or the head
  • Begins to babble, imitates sounds and words, and brings the hands to the mouth
  • Has single words like “mama” or “papa”, repeats sound or gestures for attention
  • Turns head toward direction of the sound, responds when called by her/his name
  • Pushes down on legs when feet placed on a firm surface; raises head and chest when lying on stomach
  • Smiles at mother or primary care-givers voice prefers them over all others
  • Can sit up without assistance, can pull self up to stand, walks holding on to furniture
  • Waves ‘bye-bye’ and points to objects

Within 24 months:

  • Walks alone, with support can negotiate stairs and furniture, carries and pulls toys while walking
  • Imitates behavior of others, excited about the company of other children
  • Has several single words by 15 to 18 months; uses simple phrases by 24 months

Within 36 months:

  • Uses 4-5 word sentences, understands most sentences and instructions
  • Imitates adults and playmates, expresses affection openly, separates easily from parents
  • Sorts objects by shape and color
  • Climbs well, runs, kicks a ball, negotiates stairs unaided

Autism Diagnosis

Early detection of autism is fundamental, as research demonstrates that the earlier in life the disorder is observed, the better the chances to start appropriate therapies to address the deficiencies of the child. Generally, autism is diagnosed in the following way for children:

  1. Pediatricians and general doctors, aware of the growing incidence of autism in the new generations, undertake specific autism detection tests at the 18th and 24th month after birth (some doctors check children even earlier, example at 9 months, or later, example at 30-36 months): with these checks, doctors try to identify possible deficiencies in terms of movements, behavior, learning, communication and speaking skills.
  2. If any doubt or issue occurs during these general checks, doctors will recommend more in-depth tests, which may include sensorial checks, developmental reviews, vision, hearing and talking tests, up to medical check-ups (genetic). These tests are executed by doctors specialized in autism or child psychologist. Special tests and checklists are used to diagnose autism, such as the so-called ADOS (autism diagnostic observation schedule) or Revised ADI-R or the Diagnostic Interview for Social and Communications Disorders (DISCO)

To diagnose autism, the symptoms shall show up early in life, be clear, be persistent, and affect the life of the child in a remarkable way. If signs have a short duration and are inconsistent, they can be attributed to causes different from autism (that doctors will investigate with other methods). One of the aspects of the diagnosis is the assessment of the severity of each deficiency, mainly in the social and communication areas.

For adults, the diagnosis generally comes after a spontaneous request from the individual.

ASD Diagnosis Process

The diagnosis of ASD is articulated in a number of typical steps:

  1. Preparation: Parents should come to the assessment well prepared, which means that they are expected to collect details about the children, like any previous analysis, test, and to note down all the atypical behaviors (autism red flags) of the child in the different circumstances. Parents should provide a truthful and accurate picture of the situation, and avoid hiding unpleasant issues
  2. Family and behavioral assessment: the first step is generally an in-depth assessment of the history of the family and of the behavioral traits of the child. Specific protocols have been developed for this phase, to make it as structured as possible (examples are the DISCO and ADOS schemes)
  3. IQ test: To test the cognitive and learning skills of the child suspected of autism, an IQ test is generally executed. Most autistic child show average or below average IQ levels, with some exceptions (for mild ASD or Asperger)
  4. Communication tests: this step, sometimes executed in cooperation with a speech pathologies expert, aims at assessing the level of verbal and non-verbal communication of the child. The main goal is to assess whether the child shows atypical communication skills and the existing deficiencies if any
  5. Medical tests: a number of physical tests are included in the assessment to ensure that the autisms symptoms are not related to physical conditions (EEG, blood test, visual examination, sensory tests, and genetic checkups)

At the end of the examination, which can take several days, the assessor issues a written report to state their conclusions. The whole process may take up to 2/3 weeks.

Parents take a positive ASD diagnosis very differently: for some, it represents a total shock, for others a sort of relief. In any case, the lives of both the parents and the child are changed by an autism diagnosis, and in some cases for the better (access to funding, support, the start of therapies, a clear understanding of the issue and how to deal with it).

Who can diagnosticate autism?

The presence, or the absence, of an autism spectrum disorder in a toddlers and young children shall be diagnosed by an ASD specialist, a multidisciplinary team, a pediatrician, a psychiatrist or a clinical psychologist experienced in the assessment of development disorder, and the diagnosis shall happen using the latest “Diagnostic and Statistical Manual of Mental Disorders (called DSM-V).

The DSM-5 methodology has been developed to make sure that diagnosis is consistent, standardized, and does not represent a stressful experience both for the individual and the family. Diagnosis can be executed either in public or private structures. As a quick assessment may be highly beneficial for the long-term results of the existing therapies (as ABA), it is recommended to consider a private test in case the waiting times at public structures are too long.

For children in schooling age or adults, a meeting with a specialized psychologist and/or psychiatrist is the best choice. In these cases, the diagnosis is a mix of psycho attitudinal, cognitive, behavioral tests, coupled with interviews aiming at rebuilding the life of the person from childhood to adulthood.

Most local autism associations keep records of the specialized doctors in the country or the area, and they can be the first reference for parents.

Why diagnosis is important?

In the case of suspects, parents are recommended to look for a diagnosis for a number of reasons:

  • An official assessment explains what is really going on with the affected individual
  • Specific therapies may be put in place, that could help the child later in life
  • Teachers, tutors, caregivers, and family members will have clearer directives on how to interact with the child
  • A diagnosis gives access to financial support (from the state) or entitles the family to get paid support from specialized therapists (instead of being, and feeling, alone)
  • Parents get a more in-depth understanding of ASD and knowledge about how to deal with this condition, even with the support of other families that share the same problem


The diagnosis of autism often involves other types of tests, to assess other areas of the child/adult cognitive or emotional setup: IQ tests (to assess the level of intelligence), ADHD, language and anxiety disorders tests.  The combination of concomitant issues is unfortunately not uncommon.

Autism Checklist

The following checklists may help the parent spot the red flags of the autism spectrum disorder. Consult an expert in autism if you have 5 or more positive answers for each ASD checklist.

Autism checklist for toddlers

  1. Does your child avoid eye contact with you (she/he doesn’t look at you when you talk to him or call him)?
  2. Does your child look indifferent when you smile her/him, without returning the smile or feeling any emotion?
  3. Does your child ignore you when you call her/him, or when someone in the family speaks or come close?
  4. If you point an object with your hand, does your look indifferent and do not look in the same direction?
  5. Does your child avoid using any non-verbal communication such as facial expressions, waving of hands, physical gestures?
  6. Do you have the impression that your child lives in “another world” and that she/he is indifferent to your stimuli and doesn’t seem to call for your attention?
  7. Is your child indifferent to cuddling, and does not seem to search for it?
  8. Does your child seem unable to imitate your movements, facial expressions, and tone of voice?
  9. Does your child prefer isolation than playing with other kids?
  10. Does your child look indifferent if you cry, or if you simulate pain and other signs of distress or discomfort?

Autism checklist for older children

In older children (example pre-schooling, schooling age), autism shows up as impaired social skills, communication problems, lack of flexibility, and learning delays.

ASD social skills impairment checklists

  • Is your child totally uninterested or unaware of what is going on around them (for example, when other children or family members are around)?
  • Does your child have severe issues when it comes to making friends, play or connect with peers or family members (and this cannot be traced back to shyness)?
  • Does your child become anxious when touched, held, or cuddled?
  • Doesn’t your child refrain from playing with games, or arrange available objects in order to invent new games, even if stupid)?
  • Does your child have trouble understanding and talking about own and other people’s feelings?
  • Does your child seem to be not interested in getting other people’s recognition or attention (but rather prefer to hide)?

ASD communication/language skills impairment checklists

  • Does your child speak with a very flat and unemotional tone of voice?
  • Does your child seem to talk only asking questions, and never making firm statements?
  • Does your child answer to your question, by repeating the question itself instead of formulating a real answer (maybe repeating the question multiple times)?
  • Did you notice your child repeated the same words again and again, even alone, and without any intention to communicate?
  • Did you notice an excessive rate of grammatical errors and wrong words in your child talks, which are uncommon given the age?
  • Do you feel that your child is at discomfort with imaginative and metaphoric talking, and tends to take everything you say literally, struggling with more complex reasoning?
  • Does your child talk about himself as talking about another person?
  • Do you sense that your child has severe issues in communicating her/his feelings, desires, needs?
  • Did you ever think that your child is mentally retarded due to limited comprehension and talking abilities?
  • Does your child lack the ability to understand ironic, funny, sarcastic talking?
  • Does your child have often facial expressions totally out of tune with what he is trying to say?
  • Does your child use little, if any, non-verbal communication like changing facial expressions, change of tone of the voice, gestures, pointing at things, hands movements?
  • Does your child react abnormally to loud noises (anxiety, distress) and looks unable to distract from them?

ASD behavioral skills impairment checklists

  • Does your child follow a rigid routine and becomes very anxious when a change occurs?
  • Does your child react badly when something is changed at home, like furniture, the position of households, or when certain domestic habits are changed (new time for lunch or dinner, or bedtime)?
  • Does your child have an obsessive interest for few objects at home and ignores the others?
  • Does your child show obsession for keeping things in a certain order and rearrange their position over and over?
  • Have you caught your child starring at rotating objects for hours (example: a spinning washing machine, a fan, a wheel)?
  • Does your child repeat over and over some specific movements, or when she/he feels in distress or happy? Examples are flapping the hands, stimming, banging the arms against the furniture, etc.?
ASD in toddlersAutism checklistsAutism in adultsAutism symptomsCauses of autismSigns of autism


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  • joan d. rafael
    1:12 PM, 19 January 2020

    yes.. i agree with all those above because manifestations of autism mentioned were the same to my son

  • Jocelyn C. Revilla
    10:57 AM, 27 January 2020

    Very informative.

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