Many parents with an autistic child will go to many different specialists looking for a precise diagnosis. Unfortunately, diagnosing autism is not like diagnosing measles or a specific chromosomal defect such as Down syndrome. Even though autism is a neurological disorder, it is still diagnosed by observing a child's behavior. There is no blood test or brain scan that can give an absolute diagnosis, though brain scans may partially replace observation in the future.
The new diagnostic categories are autism, pervasive developmental disorder (PDD), Asperger's syndrome, and disintegrative disorder, and there is much controversy among professionals about them. Some consider these categories to be true separate entities, and others believe that they lie on an autistic continuum and there is no definite distinction between them.
A three-year-old child would be labeled autistic if he or she lacked both social relatedness and speech or had abnormal speech. This diagnosis is also called classic Kanner's syndrome, after Leo Kanner, the physician who first described this form of autism, in 1943. These individuals usually learn to talk, but they remain very severely handicapped because of extremely rigid thinking, poor ability to generalize, and no common sense. Some of the Kanner people have savant skills, such as calendar calculation. The savant group comprises about 10 percent of the children and adults who are diagnosed.
A child with classic Kanner's syndrome has little or no flexibility of thinking or behavior. Charles Hart describes this rigidity in his autistic brother, Sumner, who had to be constantly coached by his mother. He had to be told each step of getting undressed and going to bed. Hart goes on to describe the behavior of his autistic son, Ted, during a birthday party when ice cream cones were served. The other children immediately began to lick them, but Ted just stared at his and appeared to be afraid of it. He didn't know what to do, because in the past he had eaten ice cream with a spoon.
Another serious problem for people with Kanner's syndrome is lack of common sense. They can easily learn how to get on a bus to go to school, but have no idea what to do if something interrupts the routine. Any disruption of routine causes a panic attack, anxiety, or a flight response, unless the person is taught what to do when something goes wrong. Rigid thinking makes it difficult to teach people with Kanner-type autism the subtleties of socially appropriate behavior. For example, at an autism meeting, a young man with Kanner's syndrome walked up to every person and asked, «Where are your earrings?» Kanner autistics need to be told in a clear simple way what is appropriate and inappropriate social behavior.
Uta Frith, a researcher at the MRC Cognitive Development Unit in London, has found that some people with Kanner's syndrome are unable to imagine what another person is thinking. She developed a «theory of mind» test to determine the extent of the problem. For example, Joe, Dick, and a person with autism are sitting at a table. Joe places a candy bar in a box and shuts the lid. The telephone rings, and Dick leaves the room to answer the phone. While Dick is gone, Joe eats the candy bar and puts a pen in the box. The autistic person who is watching is asked, «What does Dick think is in the box?» Many people with autism will give the wrong answer and say «a pen.» They are not able to figure out that Dick, who is now outside the room, thinks that the box still contains a candy bar.
People with Asperger's syndrome, who tend to be far less handicapped than people with Kanner-type autism, can usually pass this test and generally perform better on tests of flexible problem-solving than Kanner's syndrome autistics. In fact, many Asperger individuals never get formally diagnosed, and they often hold jobs and live independently. Children with Asperger's syndrome have more normal speech development and much better cognitive skills than those with classic Kanner's. Another label for Asperger's syndrome is «high-functioning autism.» One noticeable difference between Kanner's and Asperger's syndromes is that Asperger children are often clumsy. The diagnosis of Asperger's is often confused with PDD, a label that is applied to children with mild symptoms which are not quite serious enough to call for one of the other labels.
Children diagnosed as having disintegrative disorder start to develop normal speech and social behavior and then regress and lose their speech after age two. Many of them never regain their speech, and they have difficulty learning simple household chores. These individuals are also referred to as having low-functioning autism, and they require supervised living arrangements for their entire lives. Some children with disintegrative disorder improve and become high-functioning, but overall, children in this category are likely to remain low-functioning. There is a large group of children labeled autistic who start to develop normally and then regress and lose their speech before age two. These early regressives sometimes have a better prognosis than late regressives. Those who never learn to talk usually have severe neurological impairments that show up on routine tests. They are also more likely to have epilepsy than Kanner or Asperger children. Individuals who are low-functioning often have very poor ability to understand spoken words. Kanner, Asperger, and PDD children and adults usually have a much better ability to understand speech.
Children in all of the diagnostic categories benefit from placement in a good educational program. Prognosis is improved if intensive education is started before age three. I finally learned to speak at three and a half, after a year of intensive speech therapy. Children who regress at eighteen to twenty-four months of age respond to intensive educational programs when speech loss first occurs, but as they become older they may require calmer, quieter teaching methods to prevent sensory overload. If an educational program is successful, many autistic symptoms become less severe.
The only accurate way to diagnose autism in an adult is to interview the person about his or her early childhood and obtain descriptions of his or her behavior from parents or teachers. Other disorders with autistic symptoms, such as acquired aphasia (loss of speech), disintegrative disorder, and Landau-Kleffner syndrome, occur at an older age. A child may have normal or near-normal speech and then lose it between the ages of two and seven. In some cases disintegrative disorder and Landau-Kleffner syndrome may have similar underlying brain abnormalities. Landau-Kleffner syndrome is a type of epilepsy that often causes a child to lose speech. Small seizures scramble hearing and make it difficult or impossible for the child to understand spoken words. A proper diagnosis requires very sophisticated tests, because the seizures are difficult to detect. They will not show up on a simple brain-wave (EEG) test. These disorders can often be successfully treated with anticonvulsants (epilepsy drugs) or corticosteroids such as prednisone. Anticonvulsant medications may also be helpful to autistic children who have abnormal EEGs or sensory scrambling. Other neurological disorders that have symptoms of autism are Fragile X syndrome, Rhett's syndrome, and tuberous sclerosis. Educational and treatment programs that help autistic children are usually helpful for children with these disorders also.
There is still confusion in diagnosing between autism and schizophrenia. Some professionals claim that children with autism develop schizophrenic characteristics in adulthood. Like autism's, schizophrenia's current diagnostic criteria are purely behavioral, though both are neurological disorders. In the future, brain scans will be sophisticated enough to provide an accurate diagnosis. Thus far, brain research has shown that these conditions have different patterns of abnormalities. By definition, autism starts in early childhood, while the first symptoms of schizophrenia usually occur in adolescence or early adulthood. Schizophrenia has two major components, the positive symptoms, which include full-blown hallucinations and delusions accompanied by incoherent thinking, and the negative symptoms, such as flat, dull affect and monotone speech. These negative symptoms often resemble the lack of affect seen in adults with autism.