For substance use disorders, new biomarkers that improve on existing technology are highly desirable. But in addition to the general factors listed above, researchers must consider additional factors specific to substance use disorders when considering whether potential biomarkers will improve on current technology. First, given that substance use is often intermittent, biomarkers must offer adequate stability and persistence to allow detection at a future time point. Lack of persistence over time is a considerable weakness in current biomarkers for substance use (see Table 1). Next, specificity for the type of exposure is essential. For example, given frequent comorbid patterns of substance use, distinguishing between new-onset cannabis use in the setting of ongoing tobacco smoking may be needed. Third, specificity with respect to cumulative exposure is important, as for many substances such as tobacco and alcohol, adverse outcomes are most strongly related to cumulative exposure. Fourth, the ability to detect initial cessation of use and ongoing abstinence is essential in implementing appropriate monitoring and assessing response to treatment. Fifth, specificity with respect to the exposure window is an important consideration for the development of the ability to detect specific kinds of exposure such as prenatal exposure.
