can be noticed during infancy. It is usually noticed during early childhood, which is between the ages of 2-6 years. The severity of symptoms varies. Children with autism may show a combination of behaviors. Autism is a lifelong condition.
Each child is different. Symptoms fall into 4 broad categories: Poor or limited social relationshipsUnderdeveloped communication skillsRepetitive behaviors and unusual interests and activitiesSigns of altered and confused sensory input
Children develop and change rapidly at this early stage. Symptoms often take the form of failure to progress. A child may also regress from previous achievements. Something wrong may be noticed at birth. However, it is more common to notice something wrong when your child is a toddler. They may not achieve normal social and developmental milestones.
The range of unusual behaviors is wide. Children have many different combinations of behaviors.
Symptoms may include: Avoiding eye contactAvoiding social contact and preferring to be aloneNot imitating othersNot understanding other people's feelings and needsFailing to seek and even avoid personal attentionBeing physically aggressiveBeing self-destructiveOften having tantrums, even with very little to provoke them
Symptoms may include: Never speaking—Some children with autism may not be able to learn how to speak. Or, they may only speak a few words.Using language in unusual ways. Some children use incorrect words and change the meaning of common words.Only echoing what they have heard, and speaking on their own.Trouble with nonverbal communication—Body language is used and interpreted wrongly. For example, a hug may be considered an assault.Not reacting to smiles the way a normal child would.
Autistic children usually: Do not play imaginativelyLack interest in normal activities for their ageMay spend hours doing a single activity over and over again. For example, rocking or flapping a handMay gesture frequently, or stare at specific objectsDemand consistency and predictability in their surroundings—Tiny changes may cause angry reactionsMay be hyperactive, passive, and single-mindedResist change
Signs may include: An unusual sensitivity to sound, smell, taste, sights, and touchResponding to stimulation in unusual waysSniffing or licking toysFeeling pain from a light touch, but ignoring more severe painExperiencing sounds as colors, and touches as sounds
Some people with autism have other disorders as well. These may include: Seizures
—These occur when communication between nerve cells in the brain is disturbed. This can cause strange sensations, emotions, and behavior. Also common are convulsions, muscle spasms, and loss of consciousness.
—A condition that includes limitations in both intelligence and adaptive skills.
Conditions affecting digestion, such as:
Gastroesophageal reflux disease (GERD)
MalabsorptionDiarrheaNot having a lot of food interestsFailure-to-thrive
Genetic disorders—Examples include:
—This is a neurological disorder. The symptoms are tics, rapid, involuntary movements, or sounds that occur repeatedly.
Fragile X syndrome
—This is an inherited disorder of the X chromosome. It is the most common cause of inherited intellectual disability.
(PKU)—PKU is a genetic disorder of the enzyme that breaks down phenylalanine. Phenylalanine is an amino acid found in certain foods. Without a proper diet, PKU can lead to intellectual disability.
Tuberous sclerosis—This is a genetic disorder of the nervous system. It causes tumors to grow on the nerves in any part of the body. Neurofibromatosis can also produce other abnormalities. For example, changes in the skin or deformed bones.
About autism. The Autism Society website. Available at:
http://www.autism-society.org/what-is. Accessed March 14, 2017.
Autism spectrum disorder. National Institute of Mental Health website. Available at:
Updated October 2016. Accessed March 14, 2017.
Behrman RE, et al.
Nelson Textbook of Pediatrics. 18th ed. Philadelphia: Saunders, 2007.
Goetz’s Textbook of Clinical Neurology.
3rd ed. Philadelphia: Saunders, 2007.
Jacobson JL, Jacobson AM.
Psychiatric Secrets. 2nd ed. Philadelphia: Hanley & Belfus, 2001.
Stern TA, et al.
Massachusetts General Hospital Comprehensive Clinical Psychiatry. 1st ed. Philadelphia: Mosby Elsevier, 2008.
Last reviewed March 2017 by Adrian Preda, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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