Effects of khat use on response to antipsychotic medications in patients with newly diagnosed schizophrenia: a retrospective study

Abstract

Background: Khat contains the amphetamine-like cathinone, and can trigger onset of schizophrenia and exacerbate pre-existing psychosis. However, it remains unknown whether the use of khat complicates the outcome of schizophrenia treatment. Aims: We tested the hypothesis that patients with schizophrenia who are using khat will fail to respond to standard antipsychotic treatment. Methods: We retrospectively studied a consecutive series of patients who presented to an adult psychiatric clinic in Al-Amal Psychiatric Hospital in Jazan, Saudi Arabia, between January 1, 2013 and December 31, 2016. Patients with newly diagnosed schizophrenia on antipsychotic monotherapy (n = 1007, 817 men) were included and categorized into khat and non-khat users. A khat chewing index was developed to further categorize low, mild, moderate and heavy khat users. Antipsychotic medications were reviewed to determine their potential and the cause of substitution in association with khat use. Results: There were 483 (48%) khat users. Olanzapine, haloperidol and aripiprazole were the most frequently used drugs (46.3%, 15.6% and 10%, respectively). The retention rate of the initial drug differed between the khat users and nonusers (53.8% and 78.4%, respectively). The proportion of moderate and heavy users (55% and 49%, respectively) who changed their initial drug was greater than that of low and mild users (35.6% and 44.7%, respectively). Lack of drug efficacy was the most appealing reason for switching the initial drug among moderate (51.7%) and heavy khat users (48.4%). Conclusions: Khat use hinders an individual’s response to initial antipsychotic drug treatment for schizophrenia. Further studies are warranted to investigate the treatment decisions for this group of patients.