Editing Mental disorder (section)

===Dimensional models===
The high degree of [[comorbidity]] between disorders in categorical models such as the DSM and ICD have led some to propose dimensional models. Studying comorbidity between disorders have demonstrated two latent (unobserved) factors or dimensions in the structure of mental disorders that are thought to possibly reflect etiological processes. These two dimensions reflect a distinction between internalizing disorders, such as mood or anxiety symptoms, and externalizing disorders such as behavioral or substance use symptoms.<ref>{{cite journal | vauthors = Hankin BL, Snyder HR, Gulley LD, Schweizer TH, Bijttebier P, Nelis S, Toh G, Vasey MW | title = Understanding comorbidity among internalizing problems: Integrating latent structural models of psychopathology and risk mechanisms | journal = Development and Psychopathology | issn = 0954-5794 | eissn = 1469-2198 | volume = 28 | issue = 4pt1 | pages = 987–1012 | date = November 2016 | pmid = 27739389 | pmc = 5119897 | doi = 10.1017/S0954579416000663 }}</ref> A single general factor of psychopathology, similar to the [[G factor (psychometrics)|g factor]] for intelligence, has been empirically supported. The ''p factor'' model supports the internalizing-externalizing distinction, but also supports the formation of a third dimension of thought disorders such as schizophrenia.<ref>{{cite journal | vauthors = Caspi A, Houts RM, Belsky DW, Goldman-Mellor SJ, Harrington H, Israel S, Meier MH, Ramrakha S, Shalev I, Poulton R, Moffitt TE | title = The p Factor: One General Psychopathology Factor in the Structure of Psychiatric Disorders? | journal = Clinical Psychological Science | volume = 2 | issue = 2 | pages = 119–137 | date = March 2014 | pmid = 25360393 | pmc = 4209412 | doi = 10.1177/2167702613497473 }}</ref> Biological evidence also supports the validity of the internalizing-externalizing structure of mental disorders, with twin and adoption studies supporting heritable factors for externalizing and internalizing disorders.<ref>{{cite journal | vauthors = Forbes MK, Tackett JL, Markon KE, Krueger RF | title = Beyond comorbidity: Toward a dimensional and hierarchical approach to understanding psychopathology across the life span | journal = Development and Psychopathology | issn = 0954-5794 | eissn = 1469-2198 | volume = 28 | issue = 4pt1 | pages = 971–986 | date = November 2016 | pmid = 27739384 | pmc = 5098269 | doi = 10.1017/S0954579416000651 }}</ref><ref>{{cite journal | vauthors = Gizer IR | title = Molecular genetic approaches to understanding the comorbidity of psychiatric disorders | journal = Development and Psychopathology | issn = 0954-5794 | eissn = 1469-2198 | volume = 28 | issue = 4pt1 | pages = 1089–1101 | date = November 2016 | pmid = 27739393 | pmc = 5079621 | doi = 10.1017/S0954579416000717 }}</ref><ref>{{cite journal | vauthors = Lahey BB, Krueger RF, Rathouz PJ, Waldman ID, Zald DH | title = A hierarchical causal taxonomy of psychopathology across the life span | journal = Psychological Bulletin | volume = 143 | issue = 2 | pages = 142–186 | date = February 2017 | pmid = 28004947 | pmc = 5269437 | doi = 10.1037/bul0000069 }}</ref> A leading dimensional model is the [[Hierarchical Taxonomy of Psychopathology]].