580 Substance-Related and Addictive Disorders
Development and Course
No single pattern of development or course  characterizes the pharmacologically varied
other (or unknown) substance use disorders.  Often unknown substance use disorders will
be reclassified when the unknown substance eventually is identified. 
Risk and Prognostic Factors
Risk and prognostic factors for other (or un known) substance use disorders are thought to
be similar to those for most substance use disorders and include the presence of any other
substance use disorders, conduct disorder, or antisocial personality disorder in the indi-
vidual or the individual’s family; early onse t of substance problems ; easy availability of
the substance in the individual’s environment; childhood maltreatment or trauma; and ev-
idence of limited early self-control and behavioral disinhibition. 
Culture-Related Diagnostic Issues
Certain cultures may be associated with ot her (or unknown) substance use disorders in-
volving specific indigenous substances with in the cultural region, such as betel nut.
Diagnostic Markers
Urine, breath, or saliva tests may correctly identify a commonly used substance falsely
sold as a novel product. However, routine clin ical tests usually cannot identify truly un-
usual or new substances, which may requir e testing in specialized laboratories. 
Differential Diagnosis
Use of other or unknown substances without meeting criteria for other (or unknown)
substance use disorder. Use of unknown substances is not rare among adolescents, but
most use does not meet the diag nostic standard of two or mo re criteria for other (or un-
known) substance use disorder in the past year.
Substance use disorders. Other (or unknown) substanc e use disorder may co-occur
with various substance use diso rders, and the symptoms of the disorders may be similar