non-adherence, heightened suicide risk and adverse long-term clinical out comes compared to patients with psychosis who do not use illicit drugs. Some of the most frequently used illicit drugs,cannabis and
stimulants, may induce transient positive psychosis symptoms and cognitive alterations
.A majority of patients with schizophrenia and non-affective
Psychoses have clinical significant cognitive deficits
, often depicted as a vulnerability factor that is present also before the development of psychosis and in high-risk populations. It is likely, however, that theuse of illicit drugs influences cognition in psychosis. Experimental studies have shown that the most prominent
Psychoactive substance in cannabis, Delta-9-tetrahydrocannabinol(THC), have an especially strong negative effect on cognition in individuals with psychosis