Khat (Catha edulis) and Obesity: A Scoping Review of Animal and Human Studies.

BACKGROUND: Khat (Catha edulis) is a plant that is deeply rooted in the cultural life of East African and Southwestern Arabian populations. Prevalent traditional beliefs about khat are that the plant has an effect on appetite and body weight. SUMMARY: This review assesses the accumulated evidences on the mutual influence of monoamines, hormones and neuropeptides that are linked to obesity. A few anti-obesity drugs that exert their mechanisms of action through monoamines are briefly discussed to support the notion of monoamines being a critical target of drug discovery for new anti-obesity drugs. Subsequently, the review provides a comprehensive overview of central dopamine and serotonin changes that are associated with the use of khat or its alkaloids. Then, all the studies on khat that describe physical, biochemical and hormonal changes are summarised and discussed in depth. CONCLUSION: The reviewed studies provide relatively acceptable evidence that different khat extracts or cathinone produces changes in terms of weight, fat mass, appetite, lipid biochemistry and hormonal levels. These changes are more pronounced at higher doses and long durations of intervention. The most suggested mechanism of these changes is the central action that produces changes in the physiology of dopamine and serotonin. Nonetheless, there are a number of variations in the study design, including species, doses and durations of intervention, which makes it difficult to arrive at a final conclusion about khat regarding obesity, and further studies are necessary in the future to overcome these limitations.

Khat dependence syndrome: a cross sectional preliminary evaluation amongst UK-resident Yemeni khat chewers.

ETHNOPHARMACOLOGICAL RELEVANCE: Khat is a natural psychostimulant that has pharmacological effects similar to that of amphetamine. The behaviour of khat chewing is embedded within a cultural context. Meanwhile khat chewing is associated with psychological and physiologically burden, as a 'dependence producing' substance. AIMS OF THE STUDY: To assess the applicability of the construct of substance dependence syndrome (DSM-IV, 1994) to khat chewing and to examine psychosocial and behavioural correlates of this syndrome including tobacco use. MATERIALS AND METHODS: A sample of 204 khat chewers was recruited during random visits to khat sale outlets. A face to face interview that assessed socio-demographic, psychosocial dependence, substance dependence syndrome and behavioural characteristics was conducted. Descriptive, exploratory psychometric and multivariate analyses were employed. RESULTS: Approximately a third (31%) of khat chewers reported symptoms consistent with dependence syndrome including increased khat chewing (13%) and cessation attempts (19%) while 17% reported withdrawal symptoms including depression (61%), increase in appetite (74%) and interrupted sleep (58%). Thirty-eight percent reported continued khat chewing despite impacts on their health. Psychometric assessment of the DSM-IV criteria for khat chewing dependence identified two factors; factor 1 consisted of bio-behavioural items and factor 2 withdrawal items, accounting for 67% of the variance and Cronbach's alpha coefficient at 0.78. In multivariate logistic regression modelling, there was an association between intensity of psychological khat dependence (SDS-Khat) and nicotine dependence with the likelihood of exhibiting khat chewing dependence syndrome (p=0.0005, OR=1.51, 95%CI=1.33-1.71; p=0.043, OR=2.87, 95%CI=1.03-7.98, respectively). CONCLUSIONS: The substance dependence syndrome criteria are applicable to khat chewing and associated with increased intensity of nicotine and psychological khat dependence. The applicability of khat dependence syndrome and exploration of its dimensions and associated factors should be extended in future research. Concurrent validation of these findings using specific objective measures for self-report khat chewing is also recommended.

Validation of self-reported khat chewing amongst khat chewers: an exploratory study.

ETHNOPHARMACOLOGICAL RELEVANCE: Khat chewing amongst the UK communities originating from Yemen and the East African coast is suggested to create dependency through its main stimulant components (cathinone, norephedrine and norpseudoephedrine) on the central nervous system. AIMS OF THE STUDY: To validate self-reported khat chewing behaviours by measuring levels of cathinone, norephedrine and norpseudoephedrine in saliva and to explore their associations with self-reported khat chewing dependency. MATERIALS AND METHODS: Face-to-face interviews were conducted amongst 30 male UK-resident khat chewers. Saliva samples were collected from each participant and high-performance liquid chromatography (HPLC) employed to extract and quantify the levels of the biomarkers. RESULTS: The mean (SD) for cathinone and the composite norephedrine and norpseudoephedrine levels were 33.93 (±39.20) and 29.28 (±26.32)µg/mL respectively. These biomarkers were significantly associated (p≤0.05) with khat chewing dependency. CONCLUSIONS: Validation of self-reported khat chewing is possible. Khat chewing dependency correlates significantly with biomarker levels in saliva. Replication is required.

Validity and reliability of a Severity of Dependence Scale for khat (SDS-khat).

AIMS OF THE STUDY: (1) To assess psychological khat dependence and (2) to assess the validity and reliability of the Severity Dependence Scale (Gossop et al., 1995) amended for khat use (SDS-khat), in a sample of UK-resident male adult Yemeni khat chewers. MATERIALS AND METHODS: A cross-sectional study using a face to face structured interview schedule was conducted amongst purposively sampled UK-resident adult Yemeni male khat chewers, aged 18 years and above, selected during random visits to places of khat sale. A factor analysis with principal components extraction was conducted to explore the construct validity of the proposed SDS-khat. Reliability of the proposed scale was assessed using test-retest and internal reliability tests. The concurrent validity of the proposed SDS-khat was assessed in relation to individual measures and a composite index of khat chewing behaviours using univariate analyses. RESULTS: Two hundred and four Yemeni male adult khat chewers were interviewed. The mean score of the proposed SDS-khat was 5.52 (SD ±4.03). Forty nine percent of respondents (95% CI=43-55%) with ≤5 scores were more likely not psychologically dependent. A single factor, uni-dimensional solution identifying the five items making up the scale accounted for 52.33% of variance. The internal reliability was good (Cronbach's alpha coefficient=0.76) and the test retest intraclass correlation coefficient (ICC) was 0.93 (95% CI=0.80-0.97). Many individual aspects of the khat chewing were significantly related to the scale. Assessment of the proposed SDS-khat's concurrent validity with individual items of khat chewing identified several significant relationships (p≤0.05) whilst the composite index of khat behaviour also identified a significant relationship (OR=14.40, 95% CI=6.71-30.89). The proposed SDS-khat also correlated with self-reported reasons for khat chewing (p≤0.001, OR=3.54; 95% CI=1.80-6.96). CONCLUSIONS: In this sample of Yemeni khat chewers the SDS-khat is recommended as a valid and reliable research tool for measuring psychological dependence upon khat. Further validation in other samples is indicated.