Symptoms of substance-induced disorders tend to reduce over hours to days with a period of abstinence [171]. With respect to amphetamine-induced psychosis, however, some people report experiencing symptoms of psychosis for months [170]. Substance-induced symptoms can have a dose-response relationship with AOD use, such that the heavier a person’s AOD use is, the more intense their symptoms are likely to be [1569, 1570]. Heavier AOD use is associated with an increased likelihood of progressing to a substance-independent disorder [1570].
In relation to symptom-management, workers should be guided by the management strategies outlined in the earlier sections of this chapter for managing symptoms of substance-induced disorders, in relation to the predominant symptoms experienced by the client. It may also be useful to explain to clients that substance-induced symptoms will likely subside after a period of abstinence and stabilisation. Providing clients with simple strategies to manage their emotions and stress may also be useful, as psychosocial stressors can cause a recurrence of substance-induced symptoms [1571]. Appendix CC describes some relaxation methods which clients may find useful. Ongoing symptom monitoring and assessment is crucial in the management of a person who is suspected of having a substance-induced disorder, both during and after discharge, as a significant proportion of people who receive a diagnosis of a substance-induced disorder are later diagnosed with independent mental disorders.
It is estimated that between 25-32% of clients who receive a diagnosis of substance-induced major depressive disorder are diagnosed with major depressive disorder one year later [1078, 1572]. Similarly, a systematic review and meta-analysis examining the transition of substance-induced psychosis to schizophrenia found that 25% of those with substance-induced psychosis transitioned to schizophrenia. The risk of transitioning to schizophrenia was highest for cannabis-induced psychosis (34%), followed by hallucinogens (26%), amphetamines (22%), opioids (12%), sedatives (10%), and alcohol (9%) [38]. Findings suggest that half of all cases who transition to a diagnosis of schizophrenia do so within two-to-three years [36, 1573]; 80% within five years [1573]. A similar proportion of people diagnosed with substance-induced psychosis are later diagnosed with bipolar disorder (24%), 50% within four years of their diagnosis of substance-induced psychosis [36].