How closely is Asperger‘s syndrome related to autism? I’m curious as I’ve got both.
Mental health conditions are diagnosed through criteria set out in the Diagnostic and Statistical Manual of Mental Disorders (DSM) produced by the American Psychiatric Association (APA). The current version is DSM-5 and the previous version was the DSM-IV.
As you pointed out in the comments, Asperger's Disorder is a variant of Autism with a separate set of diagnostic criteria. Because of this, Autism and Asperger's Disorder was a separate diagnosis under DSM-IV even though Asperger's Disorder is on the lower end of the autistic spectrum.
DSM-5 redefined the autism spectrum disorders expanding the umbrella term to encompass the previous diagnoses of autism, Asperger syndrome, pervasive developmental disorder not otherwise specified (PDD-NOS), and childhood disintegrative disorder (APA, 2013)
Using DSM-IV, patients could be diagnosed with four separate disorders: autistic disorder, Asperger’s disorder, childhood disintegrative disorder, or the catch-all diagnosis of pervasive developmental disorder not otherwise specified. Researchers found that these separate diagnoses were not consistently applied across different clinics and treatment centers. Anyone diagnosed with one of the four pervasive developmental disorders (PDD) from DSM-IV should still meet the criteria for ASD in DSM-5 or another, more accurate DSM-5 diagnosis. While DSM does not outline recommended treatment and services for mental disorders, determining an accurate diagnosis is a first step for a clinician in defining a treatment plan for a patient.
The Neurodevelopmental Work Group, led by Susan Swedo, MD (Swedo, et al. 2012), senior investigator at the National Institute of Mental Health, recommended the DSM-5 criteria for ASD to be a better reflection of the state of knowledge about autism. The Work Group believes a single umbrella disorder will improve the diagnosis of ASD without limiting the sensitivity of the criteria, or substantially changing the number of children being diagnosed.
APA (2013) Autism Spectrum Disorder Fact Sheet. [PDF Online]
Retrieved from: https://web.archive.org/web/20131006210933/http://www.dsm5.org/Documents/Autism%20Spectrum%20Disorder%20Fact%20Sheet.pdf
Swedo, S. E., Baird, G., Cook, E. H., Happé, F. G., Harris, J. C., Kaufmann, W. E., ... & Spence, S. J. (2012). Commentary from the DSM-5 workgroup on neurodevelopmental disorders. Journal of the American Academy of Child & Adolescent Psychiatry, 51(4), 347-349. doi: 10.1016/j.jaac.2012.02.013 PubMed: 22449639