Causal pathways between substance use disorders and personality pathology

A high co-occurrence between personality and substance use disorders suggests causal relationships between these conditions. Most empirical evidence strongly supports causal pathways in which (pathological) personality traits contribute to the development of a substance use disorder (i.e., primary personality disorder model). In addition, data support a heuristic model of three developmental pathways, that is, the behavioural disinhibition, stress reduction, and reward sensitivity pathways. No data from prospective studies are available on the primary substance use disorder model. It is therefore unknown as to what extent high Axis II prevalences in addicts can be accounted for by personality disorder symptoms resulting from (chronic) substance abuse. Finally, recent empirical findings with respect to the common factor model suggest a common diathesis for substance use disorder and antisocial personality disorder. In any individual case, more than one model may have explanatory value. It is possible that one model best describes the initiation of a comorbid disorder, while another describes long-term maintenance of the same comorbid association. Personality pathology may also act as a modifier of symptoms, treatment response, outcome, and course of substance use disorder, and thereby account for the strong association between both conditions. This possibility does not involve a causal relationship but may have important implications for treatment planning.