"How can you tell if a child has Asperger's Syndrome? And should we take him to a specialist to have him formally diagnosed?"
I'll answer the second question first: Yes, if you suspect Aspergers, then by all means seek a diagnosis so you will know for sure. It's better to know than not to know. If your child has Aspergers and doesn’t know, it affects him anyway. If he does know, he can minimize the negative impact -- and leverage the positive. Without the knowledge that you have Aspergers, you will often fill that void with other, more damaging explanations (e.g., "I'm a failure, weird, a disappointment, not living up to my potential, etc.").
Here are the core symptoms of Aspergers (High-Functioning Autism). If these symptoms characterize your son, then strongly consider consulting a professional:
1. Cognitive Issues-- Mindblindness, or the inability to make inferences about what another person is thinking, is a core issue for kids with Aspergers. Because of this, they have difficulty empathizing with others, and will often say what they think without considering another's feelings. The Aspergers youngster will often assume that everyone is thinking the same thing he is. For him, the world exists not in shades of gray, but only in black and white. This rigidity in thought (i.e., lack of cognitive flexibility) interferes with problem solving, mental planning, impulse control, flexibility in thoughts and actions, and the ability to stay focused on a task until completion. The rigidity also makes it difficult for an Asperger youngster to engage in imaginative play. His interest in play materials, themes, and choices will be narrow, and he will attempt to control the play situation.
2. Difficulty with Reciprocal Social Interactions-- Children and teens with Aspergers display varying difficulties when interacting with others. Some have no desire to interact, while others simply do not know how. More specifically, they do not comprehend the "give-and-take" nature of social interactions. They may want to lecture you about the Titanic, or they may leave the room in the midst of playing with a friend. They have difficulty comprehending the verbal and nonverbal cues used in typical social interactions. These include eye contact, facial expressions, body language, conversational turn-taking, perspective taking, and matching conversational and nonverbal responses to the interaction.
3. Impairments in Language Skills-- Kids with Aspergers have very specific problems with language, especially with pragmatic use of language, which is the social aspect. That is, they see language as a way to share facts and information (especially about special interests), not as a way to share thoughts, feelings, and emotions. The youngster will display difficulty in many areas of a conversation processing verbal information, initiation, maintenance, ending, topic appropriateness, sustaining attention, and turn taking. The youngster's prosody (i.e., pitch, stress, rhythm, or melody of speech) can also be impaired. Conversations may often appear scripted or ritualistic (i.e., it may be dialogue from a TV show or a movie). They may also have difficulty problem solving, analyzing or synthesizing information, and understanding language beyond the literal level.
4. Motor Clumsiness-- Many kids with Aspergers have difficulty with both gross and fine motor skills. The difficulty is often not just the task itself, but the motor planning involved in completing the task. Typical difficulties include handwriting, riding a bike, and ball skills.
5. Narrow Range of Interests and Insistence on Set Routines-- Due to the an Asperger kid's anxiety, his interactions will be ruled by rigidity, obsessions, and perseverations (i.e., repetitious behaviors or language) transitions and changes can cause. Generally, he will have few interests, but those interests will often dominate. The need for structure and routine will be most important. He may develop his own rules to live by that barely coincide with the rest of society.
6. Sensory Sensitivities-- Many Asperger kids have sensory issues. These can occur in one or all of the senses (e.g., sight, sound, smell, touch, or taste). The degree of difficulty varies from one child to another. Most frequently, the child will perceive ordinary sensations as quite intense or may even be under-reactive to a sensation. Often, the challenge in this area will be to determine if his/her response to a sensation is actually a sensory reaction or if it is a learned behavior, driven mainly by rigidity and anxiety.
The Aspergers Comprehensive Handbook
The Aspergers Comprehensive Handbook