It’s difficult to pin down how many people have autism. The question is highly political, and people with different agendas will attempt to justify different numbers. In addition, the exact boundaries of the condition are difficult to define—particularly around the question of how severe autism needs to be before it counts, and of whether Asperger’s syndrome is a form of autism or an entirely separate thing, and if it’s a form of autism where the line is and whether Asperger’s and autism cases should be grouped together. Current thinking is that autism is a spectrum, ranging from Asperger’s on one end to people facing quite profound obstacles on the other, but even this view is not without controversy. In addition, and in part because it is so nebulous, autism is underdiagnosed, particularly in adults.
Added to this is a question of what it means to be autistic. In recent years especially, there has been a move away from the medical model, and from classifying autism as a disease. Some advocates say the experiences of autistic people should not be distinguished from those of people who are not autistic, not pathologized. There is definitely a great deal of push back against the notion of curing autism, or treating it; frequently, advocates speak of dealing with it as more like a compromise, with people with autism asking that the rest of the world meet them halfway.
However autism is classified, researchers are continuing to investigate its origins. The idea that autism is caused by vaccines has been thoroughly put to rest by the scientific community, with only people who reject science still maintaining the claim, but what the causes are has proved more difficult to pin down. The most recent hypothesis is that autism originates in utero, as the brain is built while a fetus is in the womb. In the fetuses of autistic children, critical pieces are omitted.
This finding suggests that early intervention—in infancy and toddlerhood, when the brain is at its most malleable—may help ease the child’s adjustment by coaxing the brain to repair these lacunae. This will help the child best adjust to living in a world of non-autists, and dealing with the differences that entails. Unfortunately, autism, particularly in milder forms, isn’t easy to recognize during this period.