In East-African and Arab countries, khat leaves are traditionally chewed in social settings. They contain the amphetamine-like alkaloid cathinone. Especially among Somali refugees, khat use has been associated with psychiatric symptoms. We assessed khat-use patterns and psychiatric symptoms among male Somali refugees living in a disadvantaged urban settlement area in Kenya, a large group that has not yet received scientific attention. We wanted to explore consume patterns and study the associations between khat use, traumatic experiences, and psychotic symptoms. Using privileged access sampling, we recruited 33 healthy male khat chewers and 15 comparable non-chewers. Based on extensive preparatory work, we assessed khat use, khat dependence according to DSM-IV, traumatic experiences, posttraumatic stress disorder (PTSD), and psychotic symptoms using standardized diagnostic instruments that had been adapted to the Somali language and culture. Hazardous use patterns like chewing for more than 24 h without interruption were frequently reported. All khat users fulfilled the DSM-IV-criteria for dependence and 85% reported functional khat use, i.e., that khat helps them to forget painful experiences. We found that the studied group was heavily burdened by traumatic events and posttraumatic symptoms. Khat users had experienced more traumatic events and had more often PTSD than non-users. Most khat users experience khat-related psychotic symptoms and in a quarter of them we found true psychotic symptoms. In contrast, among control group members no psychotic symptoms could be detected. We found first evidence for the existence and high prevalence of severely hazardous use patterns, comorbid psychiatric symptoms, and khat use as a self-medication of trauma-consequences among male Somali refugees in urban Kenyan refugee settlements. There is a high burden by psychopathology and adequate community-based interventions urgently need to be developed.

Somali khat users in Kenya are highly burdened by multimorbidity of depression, PTSD and khat-psychotic symptoms. The main effects for time and differences in healthy vs. mentally ill khat users indicate potential of unspecific support and the specific need for mental health care in combination with substance abuse treatment. The increase of everyday functioning promises more options for alternative activities, preventing excessive use and addiction.

Khat trees are native to East Africa and the Arabian peninsula. Their leaves contain amphetamine-like alkaloids such as cathinone, cathine and norephedrine, and are chewed for their stimulating and euphorigenic effects 1 . Khat use varies by season: in the dry season, there is limited availability and market prices are high; in the rainy season, the opposite is true. Excessive use is associated with dependence and khat-induced psychosis 2 .In collaboration with the Gilgel Gibe Field Research Center of Jimma University, in Southwestern Ethiopia, we studied khat use and khat-induced psychotic symptoms in 1,100 men aged 18 to 40 years (mean 28.4 6 6.6), randomly selected from the center's population registry.Trained raters interviewed participants at two subsequent time points, i.e. during the dry season (T1; N5853) and during the rainy season, nine months later (T2; N5695). They explored khat use during the past 7 days using the Timeline Followback Method Assessment. Psychotic symptoms experienced during the past 6 months were assessed by four items from the Composite International Diagnostic Interview (CIDI) selected on the basis of previous studies 3 . Khat-induced psychotic symptoms were defined as being present during or up to 6 hours after consumption and assessed with supplementary questions 3 . Potentially traumatic experiences (e.g., assault or life-threatening injury) during the period up to T1 or since T1 were explored by an adapted version of the Life Events Checklist for DSM-5 (LEC-5) 4 . A cut-off of four experiences was fixed by median split.Urine samples were collected to analyze khat alkaloids through immunoassay tests for amphetamine.Khat use in the past 7 days was reported by 599 individuals (70.2%) at T1, and 565 (81.3%) at T2. The 6-month prevalence of khat-induced psychotic symptoms was 7.9% at T1 and 12.8% at T2.At T2, we found 225 individuals with a positive immunoassay test. In these subjects, the rate of khat-induced psychotic symptoms was 26.6% among those with a history of four or more past traumatic experiences (N5124) and 14.0% among those with a history of less than four of those experiences (N5121) (p50.015). This result could not be explained by higher khat use among the high trauma group (p>0.081 for all use indicators in the last 7 days among people with high vs. low trauma load).We also observed that recent trauma exposure was associated with elevated presence of khat-induced psychotic symptoms in individuals with low trauma exposure during the period up to T1 (with recent trauma: 28%; without recent trauma: 12%; p50.009). Among individuals with high trauma exposure during that period, additional recent trauma did not have this effect (with recent trauma: 25%; without recent trauma: 26%; p50.933).Our findings suggest that, in the general male population of an African country, traumatic experiences can sensitize to the effects of a psychomimetic substance. This is in line with the behavioral sensitization paradigm, which suggests that repeated administration of amphetamines or ...