Autism (or ASD) is a wide-spectrum disorder. This means that no two people with autism will have exactly the same symptoms. As well as experiencing varying combinations of symptoms, some people will have mild symptoms while others will have severe ones.
Very early indicators that require evaluation by an expert include:
no babbling or pointing by age 1
no single words by 16 months or two-word phrases by age 2
no response to name
loss of language or social skills
poor eye contact
excessive lining up of toys or objects
no smiling or social responsiveness
Later indicators include:
impaired ability to make friends with peers
absence or impairment of imaginative and social play
stereotyped, repetitive, or unusual use of language
restricted patterns of interest that are abnormal in intensity or focus
preoccupation with certain objects or subjects
inflexible adherence to specific routines or rituals
There are certain other characteristics which are observered in autism patients.
The way in which a person with an ASD interacts with another individual is quite different compared to how the rest of the population behaves. If the symptoms are not severe, the person with ASD may seem socially clumsy, sometimes offensive in his/her comments, or out of synch with everyone else. If the symptoms are more severe, the person may seem not to be interested in other people at all. A person with autism may often miss the cues we give each other when we want to catch somebody's attention. The person with ASD might not know that somebody is trying to talk to them. They may also be very interested in talking to a particular person or group of people, but does not have the same skills as others to become fully involved.
Empathy - Understanding and being aware of the feelings of others
A person with autism will find it much harder to understand the feelings of other people. His/her ability to instinctively empathize with others is much weaker than other people's. However, if they are frequently reminded of this, the ability to take other people's feelings into account improves tremendously. In some cases - as a result of frequent practice - empathy does improve, and some of it becomes natural rather than intellectual. Even so, empathy never comes as naturally for a person with autism as it does to others.
A number of children with an ASD do not like cuddling or being touched like other children do. It is wrong to say that all children with autism are like that. Many will hug a relative - usually the mother, father, grandmother, grandfather, teacher, and or sibling(s) - and enjoy it greatly. Often it is a question of practice and anticipating that physical contact is going to happen. For example, if a child suddenly tickles another child's feet, he will most likely giggle and become excited and happy. If that child were to tickle the feet of a child with autism, without that child anticipating the contact, the result might be completely different.
Loud noises, some smells, and lights
A person with autism usually finds sudden loud noises unpleasant and quite shocking. The same can happen with some smells and sudden changes in the intensity of lighting and ambient temperature. Many believe it is not so much the actual noise, smell or light, but rather the surprise, and not being able to prepare for it - similar to the response to surprising physical contact. If the person with autism knows something is going to happen, he can cope with it much better. Even knowing that something 'might' happen, and being reminded of it, helps a lot.
The higher the severity of the autism, the more affected are a person's speaking skills. Many children with an ASD do not speak at all. People with autism will often repeat words or phrases they hear - an event called echolalia.
The speech of a person with ASD may sound much more formal and woody, compared to other people's speech. Teenagers with Asperger's Syndrome can sometimes sound like young professors. Their intonation may sound flat.
A person with autism likes predictability. Routine is his/her best friend. Going through the motions again and again is very much part of his/her life. To others, these repetitive behaviors may seem like bizarre rites. The repetitive behavior could be a simple hop-skip-jump from one end of the room to the other, repeated again and again for one, five, or ten minutes - or even longer. Another could be drawing the same picture again and again, page after page.
A child without autism may be quite happy to first have a bath, then brush his teeth, and then put on his pajamas before going to bed - even though he usually brushes his teeth first. For a child with autism this change, bath first and then teeth, could completely put him/her out, and they may become very upset. Some people believe that helping a child with autism learn how to cope better with change is a good thing, however, forcing them to accept change like others do could adversely affect their quality of life.
A child with autism develops differently
While a child without autism will develop in many areas at a relatively harmonious rate, this may not be the case for a child with autism. His/her cognitive skills may develop fast, while their social and language skills trail behind. On the other hand, his/her language skills may develop rapidly while their motor skills don't. They may not be able to catch a ball as well as the other children, but could have a much larger vocabulary. Nonetheless, the social skills of a person with autism will not develop at the same pace as other people's.
Learning may be unpredictable
How quickly a child with autism learns things can be unpredictable. They may learn something much faster than other children, such as how to read long words, only to forget them completely later on. They may learn how to do something the hard way before they learn how to do it the easy way.
Physical tics and stimming
It is not uncommon for people with autism to have tics. These are usually physical movements that can be jerky. Some tics can be quite complicated and can go on for a very long time. A number of people with autism are able to control when they happen, others are not. People with ASD who do have tics often say that they have to be expressed, otherwise the urge does not stop. For many, going through the tics is enjoyable, and they have a preferred spot where they do them - usually somewhere private and spacious. When parents first see these tics, especially the convoluted ones, they may experience shock and worry.
People with autism often have obsessions.