In medicine, comorbidity is the presence of one or more additional conditions co-occurring with the primary one, or the effect of such additional disorders. Distinguishing between ASD and other diagnoses can be challenging because the traits of ASD often overlap with symptoms of other disorders, and the characteristics of ASD make traditional diagnostic procedures difficult.[2][3]
^Underwood L, McCarthy J, Tsakanikos E (September 2010). "Mental health of adults with autism spectrum disorders and intellectual disability". Current Opinion in Psychiatry (Review). 23 (5): 421–426. doi:10.1097/YCO.0b013e32833cfc18. PMID20613532. S2CID13735841.
^Cuthbert B (March 1, 2013). "Overlap Blurs Diagnostic Categories – NIH-funded Study". NIMH. Archived from the original on May 10, 2015. Retrieved May 26, 2015. National Institutes of Health-funded researchers discovered that people with disorders traditionally thought to be distinct – autism, ADHD, bipolar disorder, major depression and schizophrenia – were more likely to have suspect genetic variation at the same four chromosomal sites. These included risk versions of two genes that regulate the flow of calcium into cells.
^Folstein SE, Rosen-Sheidley B (December 2001). "Genetics of autism: complex aetiology for a heterogeneous disorder". Nature Reviews. Genetics. 2 (12): 943–955. doi:10.1038/35103559. PMID11733747. S2CID9331084.