do you consider this a thesis statement? Autism,this topic intrest me because autism appears during the first three years of life.Autism causes several disoders and also is four more times prevalent in boys than girls
These are straight facts, right? These two sentences do not make a thesis statement.
Your thesis statement must include factual information (which you already have) plus your position/opinion/stance. Without your position on the topic, it isn't a true thesis statement. So think of this sentence as the angle you want to take on the topic and what you intend to prove by the end of your paper. (If your statement is simply factual, then there's nothing to prove!)
Read carefully and follow ALL directions.
This is one of the very best places I've seen online to help students write good thesis statements. It shows you sentences that aren't thesis statements and how to turn each one into real thesis statements.