Autism is a neurodevelopmental disorder that affects a sufferer's ability to interact normally with other people, and which may have secondary signs and symptoms such as delayed onset of speaking in toddlers, limited facial expressions and lack of engagement with others. Symptoms can be observed in some children as early as the first year of life, according to the National Autism Association.
Autism symptoms exist along a spectrum of severity, from very mild and difficult to notice to severe and disabling. Early signs of autism among babies and toddlers include, according to the National Autism Association: a noticeable lack of smiling or other joyful expressions among children over 6 months of age; a lack of gestures, such as waves or pointing, in toddlers over 12 months; an inability to speak after 16 months; and the loss of ability to speak between the ages of 1 and 2 years. Autistic children usually avoid eye contact and often do not smile when a parent smiles at them. They rarely initiate or respond to cuddling or make noises to get parents' attention. Diagnosing autism can be difficult, due to the range of symptoms and their severity in a given case, and only a trained neurologist can offer a definitive diagnosis.