Chronic khat use and psychotic disorders : a review of the literature and future prospects

Aims: In recent decades, the traditional habit of chewing the khat leaves, which contain the amphetamine-like cathinone, has undergone profound changes in African and Arab countries, from a socially regulated use pattern to uncontrolled consumption. This is of special public mental-health concern. In this article, a review of the scientific literature on the relationship between khat use and psychosis is provided. Results: Several case studies, but only a few group and community-based studies, have addressed this topic. The studies show inconsistent results, have methodological problems, and fail to report quantitative results. Many important questions remain unaddressed. Conclusions: The frequently stated association between khat use and psychosis contrasts with the small number of sound studies. Currently, only a few conclusions can be drawn, that excessive khat use can cause brief psychotic disorders and that people with a preexisting vulnerability should be discouraged to use it. The direction of causality between general psychopathology and khat use remains unclear. This review confirms the need for quantitative, controlled, and longitudinal studies, which can help deepen the understanding of the mental-health effects and its link to the development and course of long-lasting psychosis. Introduction Khat (Catha edulis Forsk) is an evergreen shrub of the Celastraceae family, normally reaching 6m in height, but in an equatorial climate it might grow to 25 m (UNODC, 1956). Khat can be found in the Abyssinian highlands, the Horn of Africa, Eastern and Southern Africa, the Arab peninsula, and Afghanistan (Krikorian, 1983). The first historical reference to it is found in a medieval Arab manuscript from the first half of the thirteenth century (UNODC, 1956). The first botanical description goes back to the naturalist Peter Forsskål (1732–1763; Meampel, 1992). For a complete botanical description, see Nordal (1980). For commercial purposes, it is grown in altitudes of 1,500 to 2,500 m above sea level, mostly pruned to 2–7m (Kennedy, 1987; Lemessa, 2001). In Ethiopia, Yemen, Somalia, and Kenya, the fresh young leaves and tender stems are traditionally consumed for their stimulating properties (Halbach, 1972). The freshness of the plant material is considered crucial, because 48 hours after its harvest the desired properties will have largely dimin1 Universität Konstanz Michael Odenwald1 Chronic khat use and psychotic disorders: A review of the literature and future prospects