Autism falls under the category of Pervasive Developmental Disorders, which includes disorders like Rett Syndrome and Childhood Disintegrative Disorder, and then autism is then divided up in many different subtypes including Asberger’s Syndrome. Autism effects the fields of social skills, communication and stereotypical behaviors, which most people associated with things like rocking, flapping, lining things up, etc.
Depending on the individual, there may be a physical impairment, such as a brain dysfunction or a problem with development. For instance, I have worked with an autism child who is missing the corpus callosum, which is the nerve bundle in the brain that connect the two hemispheres. The common theory now is that there is both a environmental and genetic factor, but there is no proven cause of autism.
ADHD is pretty straight forward as to what it effects. The category of “ADD” is no longer – Most doctors say you can’t have the “AD” without the “HD”.
There isn’t just “one” set of symptoms because of the wide range of ways in which autism can present. A doctor would use a checklist, observations, interviews, etc before making an autism diagnosis. The same goes for ADHD. A doctor would use research methods before diagnosing someone has having the condition.
Autism and ADHA could present with each other or with a variety of other conditions – but they do not “typically” present together. Some autism symptoms could appear like inattention, but as someone who has worked with Autistic people, and have a family member diagnosed with Asbergers, you should not easily confuse someone with ADHD with someone with autism. Their functioning and behavior are different.
Most people with ADHD use medication or therapy to learn coping skills. The current argument in the medical and teaching community is whether ADHD is over or under diagnosed. Many feel that the minute anyone sees an active kid, he must be ADHD. But the common idea is that based on what we know of child development, an ADHD diagnosis should not be made until about 1st grade, because earlier than that could be inaccurate.
Autism is not really something that can be “treated”, per se. For some individuals, early intervention with therapists can help the child function more normally, as in learning proper social or self-help skills and tolerance. Many people rely on therapists to teach behavior through a method called ABA, which teaches academics, behavior and communication through a series of repetitive practices. Some use routine using picture schedules or communication devices. Medications may help with certain behaviors or medical aspects of an individuals autism. For instance, certain types of medication many decrease aggression, drooling, help with appetite or sleeping habits or self injurious behavior. There is no one way that works for autistic individuals.