ACCORDING TO SOME REPORTS, the incidence of autism seems to be increasing substantially. A growth in this tragic affliction would certainly be a cause for alarm. However, the ways in which autism is diagnosed include some very crude -- and even disingenuous -- practices, so it may not be easy to tell whether autism is in fact more prevalent today or whether words are being used more loosely. Parents whose children are late in developing speech often report that speech therapists, social workers, or school personnel tell them that calling their child "autistic" will facilitate getting the government to finance treatments that the child may need for his real problem.

Even when honestly applied, the label of autism can often be a result of incredibly crude checklists, especially when used by people with no medical training nor doctorates in related fields. School districts, especially, often have lower-level personnel evaluating children with the aid of checklists -- and calling these children "autistic" if the number of items checked exceeds some magic number or percentage.

If we were to make up a checklist of the characteristics of a mouse -- four legs, a tail, fur, two ears, a digestive tract, etc. -- a high percentage of those characteristics would also apply to a giraffe. Yet we never mistake a mouse for a giraffe, because we are also aware of the ways in which they differ. Even if the similarities reach 80 or 90 percent, we still will not say: "There's a giraffe under the kitchen sink!"

Yet, in the far more momentous decision to label a child and perhaps change the course of his education and his life, there are seldom checklists of differences between autism and other things that may share similar characteristics.

For example, a study titled "Gifted Children" by Professor Ellen Winner of Boston College found that youngsters with very high IQs "develop almost obsessive interests," "often play alone and enjoy solitude," have "prodigious memories" and "show intense reactions to noise, pain, and frustration." She adds: "They refuse to submit to any task that does not engage them and, as a result, often end up labeled as hyperactive or with an attention deficit disorder."

They can also end up being labeled autistic, because autistic children also have obsessive and anti-social behavior, as well as extreme reactions and prodigious memories. This creates a statistical problem for those trying to determine whether genuine autism is or is not increasing -- and a devastation for parents being told that their child is going to be another "Rain Man."

Overlapping characteristics among very different kinds of children make checklists dangerous in semi-professional hands -- and sometimes even in the hands of higher-level professionals, who should know better. One of the leading authorities on autism, Dr. Bernard Rimland of the Autism Research Institute in San Diego, has said: "In recent years autism has become fashionable, and the term is vastly overused."

Those who simply count "symptoms" of autism too often discount contrary evidence. Precociously intelligent preschoolers, labeled autistic because they talked late, have included little boys who became very emotionally attached to some little girl at their school, despite the fact that such emotional attachments violate the self-absorption that initially defined -- and named -- autism.

Parents report autistic labels being slapped on their kids in less than ten minutes by some psychologists and neurologists, simply because the children were uncooperative and refused to respond to even the simplest questions. In a couple of cases, a neurologist practically ripped a little toddler out of his parent's arms and proceeded to undress him, asking him questions all the while. That a distressed child refused to cooperate under these circumstances hardly seems surprising. But, when this was brought to one neurologist's attention, he brusquely declared that he had examined thousands of children. What he omitted was any evidence on how often he had been proved right and how often wrong.

Maybe there really is an increase in autism. If so, it is a serious concern that certainly ought to be addressed. But, if not, that is also a serious concern, not least for the parents needlessly put through anguish and the children needlessly sidetracked into programs that can do them more harm than good.