Mid-age most traditionnal psychosis are shown here. May age be the reason of emergence why they are often associated in abuse drug related addictions as comorbidities and/or evolving together. Sometimes drug consumption reveal them. Otherwise symptoms can be produced by consumption and, drug treatments prescribed, because of similar pattern with psychosis can be reduced or applied and suppressed after a short period of psychosis when full withdrawal obtained. Often also clinical diagnostic is not easy and last to be establishes.
Depression, induced or not by the abuse, a mood disorder or an underlying psychosis is also a common of addiction consumption. Coming with "tatonnements" with need of sufficient dosis, important side effects, medical treatments of depression is not easy and can err meanwhile addiction consumption is, at first too much a relief.
Now with the evolution of addiction and the criteria of abstinence or non abstinence of psychotropic drugs makes that it may be harder or just potentially resolved by patient's history. If psychiatric treatment are often mantained too high and/or too long, diagnostic been too soon, addiction to drug induced plastic changes in the brain, exhaustion of addicts by their abuse and change grounded their life on other things (children, faith, labor), then complete abstention can at least be tested and is often better. Sometimes because of type of product (case of cocaine - crack) or because the choice of the patient (making his/her true commitment).
These are not the only psychiatric comorbidities associated to addiction with product, some personality's disorders have been mentionned. Anyhow care not to try to play as a phychiatrist if you are not.