**
1. AS/AD :[Asperger syndrome/disorder] differs from other
autism spectrum disorders by its relative preservation of linguistic and cognitive development. [as mentioned by you: being intelligent]
2. regarding "definite diagnosis" : The diagnosis of Asperger's was eliminated in the 2013 fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and replaced by a diagnosis of autism spectrum disorder on a severity scale...because its prevalence is not firmly established.
3. since your son is adult, thus diagnosis requires painstaking clinical examination and thorough medical history gained from both the individual and other people who know the person, especially focusing on childhood behavior. THUS
4. The mainstay of management is behavioral therapy: focusing on specific deficits to address poor communication skills, obsessive or repetitive routines, and physical clumsiness.
PS
. make sure that other differential diagnosis has been given due consideration before arriving on the Syndrome like:
schizophrenia spectrum,ADHD, obsessive–compulsive disorder,
major depressive disorder, semantic pragmatic disorder, nonverbal
learning disorder,Tourette syndrome, stereotypic
movement disorder,
bipolar disorder and social-cognitive deficits due to brain damage from alcohol abuse.
. adults with AS are able to work successfully in mainstream jobs, although they may continue to need encouragement and moral support to maintain an independent life.
. You can take the help of a Counsellor or a
Psychologist to help understand his qualities
. Individuals with AS appear to have normal life expectancy, but have an increased prevalence of comorbid psychiatric conditions [thus atypical anti psychotics along with SSRIs (selective serotonin reuptake inhibitors) are generally prescribed