High-functioning autism (HFA) is a term applied to people with autism who are deemed to be cognitively "higher functioning" (IQ>70) than other people with autism. Individuals with HFA or Asperger syndrome exhibit deficits in areas of communication, emotion recognition and expression, and social interaction. There is no consensus on the definition and HFA is not a recognized diagnosis in the DSM-IV-TR or the ICD-10.
High-functioning autism is characterized by features very similar to those of Asperger syndrome. The defining characteristic most widely recognized by current psychologists and doctors is a significant delay in the development of early speech and language skills before the age of 3 years. The diagnosis criteria of Asperger syndrome exclude a general language delay.
- People with HFA have a lower verbal intelligence quotient
- Better visual/spatial skills (higher Performance IQ) than people with Asperger syndrome
- Less deviating locomotion than people with Asperger syndrome
- People with HFA more often have problems functioning independently
- Curiosity and interest for many different things, in contrast to people with Asperger syndrome
- People with Asperger syndrome are better at empathizing with another
- The male to female ratio of 4:1 for HFA is much smaller than that of Asperger syndrome
Individuals with autism spectrum disorders, including high-functioning autism, have a very high risk of developing symptoms of anxiety. While anxiety is one of the most commonly occurring mental health symptoms, children and adolescents with high functioning autism are at an even greater risk of developing symptoms.
There are many other comorbidities, or the presence of one or more disorders in addition to the primary disorder, associated with high-functioning autism. Several of these comorbid symptoms are internalized within the individual suffering from HFA. Some of these include depression, bipolar disorder, and obsessive compulsive disorder (OCD). In particular the link between HFA and OCD, has been studied. When observing the connection between HFA and OCD, both have abnormalities associated with serotonin. 
Several other comorbidities associated with HFA are external. These external symptoms include ADHD, Tourette Syndrome, and criminal behavior. While the association between HFA and criminal behavior is not completely characterized, several studies have shown that the features associated with HFA may increase the possibility of engaging in criminal behavior.  While there is still a great deal of research that needs to be done in this area, recent studies on the correlation between HFA and criminal actions suggest that there is a need to understand the attributes of HFA that may lead to violent behavior. There have been several case studies that link the lack of empathy and social naïveté associated with HFA to criminal actions. 
HFA is not accompanied with mental retardation. This characteristic distinguishes HFA from the autism spectrum; 60-70% of individuals with autism also have have mental retardation. 
Although little is known concerning the biological basis of high-functioning autism, there have been many studies revealing structural abnormalities in specific brain regions of individuals with HFA when compared to typically developing individuals. Regions identified in the social brain include the amygdala, superior temporal sulcus, fusiform gyrus area and orbitofrontal cortex. Further abnormalities have been observed in the caudate nucleus, believed to be involved in restrictive behaviors, as well as in a significant increase in amount of cortical grey matter and atypical connectivity between brain regions.
There is a belief that some vaccinations, such as the MMR or the measles/mumps vaccine, may cause autism. This was based on a research study published by Andrew Wakefield, which has been determined fraudulent and retracted. The results of this study caused some parents to take their children off of the vaccines and as a result, these diseases can cause mental retardation or death. The claim that some vaccinations cause autism has not been proven through multiple large-scale studies conducted in Japan, the United States, and others. 
Cases are typically diagnosed by 35 months of age, much earlier than those of Asperger syndrome. This phenomenon is most likely due to the early delay in speech and language. While there is no single accepted standard diagnostic measure for HFA, one of the most commonly used tools for early detection is the Social Communication Questionnaire. If the results of the test indicate an autism spectrum disorder, a comprehensive evaluation would follow and lead to the diagnosis of HFA. Some characteristics used to diagnose an individual with autism include a lack of eye contact, pointing, and severe decifits in social interactions. The Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule are two evaluations utilized in the standard diagnosis process.
There are two classifications of different social interaction styles associated with HFA. The first is an active-but-odd social interaction style classified by ADHD symptoms, poor executive functioning, and psychosocial problems. The difficulty controlling impulses could cause the active-but-odd social behaviors present in some children with HFA. The second social interaction type is a passive style. This aloof style is characterized by the lack of social initiations and could possibly be caused by social anxiety.
The main treatment for HFA involves addressing the individual symptoms. For instance, to treat anxiety, which is often associated with HFA, the main treatment is cognitive behavior therapy. While this is the tested and approved treatment for anxiety, it does not quite meet the needs associated with the symptoms of HFA. There is very little discussion of the parent's role in anxiety intervention for children and teenagers. A revised version of cognitive behavior therapy has parents and teachers acting in a role as social coaches to help the children or young adults cope with the issues they are facing. There have been several trials proving that the involvement of parents in the lives of the children affected with anxiety associated with HFA is extremely important.
No single effective intervention exists for individuals with high-functioning autism. However, there are proactive strategies, such as self-management, designed to maintain or change one’s behavior to make living with high functioning autism easier. Self-management strategies aim to provide the individual with the skills necessary to self-regulate their own behavior, leading to greater levels of independence. Improving self-management skills allows the individual to be more self-reliant rather than having to rely on an external source for supervision or control. Self-monitoring is a framework, not a rigid structure, designed to encourage independence and self-control in the individual. Self-monitoring isn’t for everyone. It requires the attention and dedication of the individual with high-functioning autism as well as the individual overseeing the progress.
A framework for self-monitoring is provided below
- Identify positive target behaviors
- Establish an alternative behavior that is positive/constructive
- Establish a self-recording sheet
- Individuals can make sure to stay on track with intended goals
- Set goals and keep them
The goal of self-monitoring is to have the individual obtain the self-monitoring skills independently without prompting.
- Autism Spectrum Quotient, a self-administered test for high-functioning autism
- Historical figures sometimes considered autistic
- Nonverbal learning disorder
- Klin, Ami (2006). "Autismo e síndrome de Asperger: Uma visão geral" [Autism and Asperger syndrome: an overview]. Revista Brasileira de Psiquiatria (in Portuguese) 28: S3–11. doi:10.1590/S1516-44462006000500002. PMID 16791390.
- Carpenter, Laura Arnstein; Soorya, Latha; Halpern, Danielle (2009). "Asperger's Syndrome and High-Functioning Autism". Pediatric Annals 38 (1): 30–5. doi:10.3928/00904481-20090101-01.
- Sanders, J (2009). "Qualitative or quantitative differences between Asperger's disorder and autism? Historical considerations". Journal of Autism & Developmental Disorders 39 (11): 1560-1567.
- Asperger's Disorder – Diagnostic and Statistical Manual of Mental Disorders Fourth edition Text Revision (DSM-IV-TR) American Psychiatric Association (2000)
- T. Attwood, Is There a Difference Between Asperger's Syndrome and High Functioning Autism?[unreliable medical source?]
- Rinehart, NJ; Bradshaw, JL; Brereton, AV; Tonge, BJ (2002). "Lateralization in individuals with high-functioning autism and Asperger's disorder: A frontostriatal model". Journal of autism and developmental disorders 32 (4): 321–331. doi:10.1023/A:1016387020095. PMID 12199137.
- Mazefsky, Carla A.; Oswald, Donald P. (2006). "Emotion Perception in Asperger's Syndrome and High-functioning Autism: The Importance of Diagnostic Criteria and Cue Intensity". Journal of Autism and Developmental Disorders 37 (6): 1086–95. doi:10.1007/s10803-006-0251-6. PMID 17180461.
- Reaven, Judy (2011). "The treatment of anxiety symptoms in youth with high-functioning autism spectrum disorders: Developmental considerations for parents". Brain Research 1380: 255–63. doi:10.1016/j.brainres.2010.09.075. PMID 20875799.
- Mazzone, Luigi; Ruta, Liliana; Reale, Laura (2012). "Psychiatric comorbidities in asperger syndrome and high functioning autism: Diagnostic challenges". Annals of General Psychiatry 11 (1): 16. doi:10.1186/1744-859X-11-16. PMC 3416662. PMID 22731684.
- Lerner, Matthew D.; Haque, Omar Sultan; Northrup, Eli C.; Lawer, Lindsay; Bursztajn, Harold J. (2012). "Emerging Perspectives on Adolescents and Young Adults With High-Functioning Autism Spectrum Disorders, Violence, and Criminal Law". Journal of the American Academy of Psychiatry and the Law 40 (2): 177–90. PMID 22635288.
- Spencer, Michael; Stanfield, Andrew; Johnstone, Eve (2011). "Brain imaging and the neuroanatomical correlates of autism". In Roth, Ilona; Rezaie, Payam. Researching the Autism Spectrum. pp. 112–55. doi:10.1017/CBO9780511973918.006. ISBN 978-0-511-97391-8.
- Wilkinson, L. A. (2008). "Self-Management for Children with High-Functioning Autism Spectrum Disorders". Intervention in School and Clinic 43 (3): 150–7. doi:10.1177/1053451207311613.