Our understanding of autism is constantly evolving, and the term now refers to a wider spectrum of children, whose symptoms range from moderate to severe. Though the exact number of children affected by autism is unknown, the numbers of children who have the condition is growing. While the primary symptoms of autism relate to social and communication skills, other symptoms are common to ADHD—including hyperactivity, aggression and attention problems. Unlike parents of children with ADHD, parents of children with autism will usually suspect problems when their child is around 18 months old, often cued by their child's lack of communication and social skills. Sometimes, an infant will develop normally, only to lose their language or social skills between ages one and two.
Autism is linked to abnormal biology and chemistry in the brain, and affects the development of social and communication skills.A number of causes for autism have been suspected, but not proven. They include diet, mercury poisoning, the inability to process vitamins or minierals, and vaccine sensitivity.Children with autism may have symptoms of ADHD.An estimated one in every 150 children have some form of autism.Many children with autism can function well in school and social activities.