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Open Access Highly Accessed Research article

Khat use as risk factor for psychotic disorders: A cross-sectional and case-control study in Somalia

Michael Odenwald12*, Frank Neuner123, Maggie Schauer12, Thomas Elbert123, Claudia Catani2, Birke Lingenfelder1, Harald Hinkel4, Heinz Häfner5 and Brigitte Rockstroh123

Author Affiliations

1 Department of Psychology, University of Konstanz, Fach D25, D-78476 Konstanz, Germany

2 Outpatient Clinic for Refugees, University of Konstanz, Feursteinstr. 55, Haus 22, D-78479 Reichenau, Germany

3 Ctr. for Psychiatry Reichenau (ZPR), Feursteinstr.55, D-78479 Reichenau, Germany

4 Worldbank, Multi-Country Demobilization and Reintegration Program in the greater Great Lakes Region of Africa, Goma, Democratic Republic of Congo

5 AG Schizophrenieforschung, Zentralinstitut für Seelische Gesundheit, J5, D-68159 Mannheim, Germany

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BMC Medicine 2005, 3:5  doi:10.1186/1741-7015-3-5

Published: 12 February 2005



Little is known about the prevalence of khat-induced psychotic disorders in East African countries, where the chewing of khat leaves is common. Its main psycho-active component cathinone produces effects similar to those of amphetamine. We aimed to explore the prevalence of psychotic disorders among the general population and the association between khat use and psychotic symptoms.


In an epidemiological household assessment in the city of Hargeisa, North-West Somalia, trained local interviewers screened 4,854 randomly selected persons from among the general population for disability due to severe mental problems. The identified cases were interviewed based on a structured interview and compared to healthy matched controls. Psychotic symptoms were assessed using the items of the WHO Composite International Diagnostic Interview and quantified with the Positive and Negative Symptoms Scale. Statistical testing included Student's t-test and ANOVA.


Local interviewers found that rates of severe disability due to mental disorders were 8.4% among males (above the age of 12) and differed according to war experiences (no war experience: 3.2%; civilian war survivors: 8.0%; ex-combatants: 15.9%). The clinical interview verified that in 83% of positive screening cases psychotic symptoms were the most prominent manifestations of psychiatric illness. On average, cases with psychotic symptoms had started to use khat earlier in life than matched controls and had been using khat 8.6 years before positive symptoms emerged. In most cases with psychotic symptoms, a pattern of binge use (> two 'bundles' per day) preceded the onset of psychotic symptoms, in contrast to controls of the same age. We found significant correlations between variables of khat consumption and clinical scales (0.35 to 0.50; p < 0.05), and between the age of onset of khat chewing and symptom onset (0.70; p <0.001).


Evidence indicates a relationship between the consumption of khat and the onset of psychotic symptoms among the male population, whereby not the khat intake per se but rather early onset and excessive khat chewing seemed to be related to psychotic symptoms. The khat problem must be addressed by means other than prohibition, given the widespread use and its role in Somali culture.