Background: Many schizophrenic patients with a long-term administration of antipsychotic
drugs do not regularly adhere to the prescribed pharmacotherapy. Antipsychotic drugs constitute
a palliative, but not a curative treatment, and the long-term effect of these drugs is not secure.
Patients tend to consume nicotine and alcohol, as well as some patients consume drugs such as cannabis
Objective: The objective of this mini-review is to examine the reasons for the high tendency of
schizophrenic patients to consume alcohol, nicotine and drugs and in addition to suggest measures to
reduce the abuse of substances and drugs. The effects of substances such as alcohol and nicotine and
drugs such as cannabis and amphetamines on the disease outcome will be mentioned.
Method: Previous reviews on the psychotic disorders and the pharmacological treatment were used
to examine the effects of substances and drugs on schizophrenic symptoms and to investigate appropriate
measures to improve medication adherence and the renouncement of consuming substances
Results: A possible coherence between the function of single susceptibility genes and the alteration
of neurotransmitters is mentioned. The mechanism of action of the most important secondgeneration
antipsychotic drugs and their indications are described. The tendency of schizophrenic
patients to consume alcohol and nicotine and in addition the effect of both substances to possibly
worsen psychotic symptoms are pointed out. The effect of nicotinergic agonists to support smoking
cessation is described. The different compounds of cannabis, tetrahydrocannabidiol (a psychotomimetic)
and cannabidiol (exerts antipsychotic actions), are mentioned. Because a reduced adherence
to the pharmacotherapy is frequently combined with the abuse of substances, additional drugs,
psychoeducation and the administration of long-acting injectable antipsychotic drugs could reduce
the abuse of substances and drugs; these strategies could help to maintain the antipsychotic administration.
Conclusion: The abuse of drugs and substances might be combined with a reduced adherence to the
antipsychotic pharmacotherapy. Drugs and substances might in some cases worsen the psychotic
symptoms. Appropriate measures to reduce substance and drug abuse as well as to improve the adherence
to the antipsychotic pharmacotherapy are cognitive behavioral therapy, psychoeducation and
the administration of long-acting injectable antipsychotic drugs. Some new drugs, for example the
cannabis compound cannabidiol that shows antipsychotic properties and ß-varenicline, a nicotinergic
cholinergic agonist, might be administered when substance abuse (cannabis, nicotine) occurs.