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

Sucht

Volumn 53, Issue 1, 2007, Pages 9-22

  Odenwald, Michael ^a,b  

^a UNIVERSITY OF KONSTANZ   (Germany)

^b Abteilung Klinische Psychologie   (Germany)

Author keywords

Khat; Psychosis; Qat; Review; Schizophrenia

Indexed keywords

CATHA EDULIS EXTRACT; CATHINONE;

CENTRAL NERVOUS SYSTEM; HUMAN; MASTICATION; MENTAL HEALTH; NONHUMAN; PLANT LEAF; PREVALENCE; PSYCHOSIS; REVIEW; SCHIZOPHRENIA;

EID: 33947579296     PISSN: 09395911     EISSN: None     Source Type: Journal    
DOI: 10.1463/2007.01.03     Document Type: Review

References (127)

1. ACMD. (2005). Khat (Qat): assessment of risk to individual and communities in the UK. In Advisory Council on the Misuse of Drugs (ACMD) (Eds.). London: British Home Office.
2. Ahmed, A. G. & Salib, E. (1998). The khat users: A study of khat chewing in Liverpool's Somali men. Medicine, Science and the Law, 38 (2), 165-169.
3. Al-Ghdaian, A. A. (1983). Khat in the Shari'ah (islamic law). Paper presented at the International conference on Khat: The Health and Socio-Economic Aspects of Khat use, Antananaribo, Madagascar.
4. Al-Habori, M. (2005). The potential adverse effects of habitual use of Catha edulis (khat). Expert Opinion on Drug Safety, 4 (6), 1145-1154.
5. Al-Hebshi, N. N. & Skaug, N. (2005). Khat (Catha edulis)-an updated review. Addiction Biology, 10 (4), 299-307.
6. Al-Motarreb, A., Baker, K. & Broadley, K. J. (2002). Khat: pharmacological and medical aspects and its social use in Yemen. Phytotherapy Research: PTR., 16 (5), 403-413.
7. Alem, A., Kebede, D. & Kullgren, G. (1999). The prevalence and socio-demographic correlates of khat chewing in Butajira, Ethiopia. Acta Physiologica Scandinavica, Supplementum, 397, 84-91.
8. Alem, A. & Shibre, T. (1997). Khat induced psychosis and its medico-legal implication: A case report. Ethiopian Medical Journal, 35 (2), 137-139.
9. Alkan, M. L. & Ali, A. A. (2001). Report of a medical mission to Somaliland, 2001. Rural and Remote Health, 1 (1), 87.
10. Angrist, B., Rotrosen, J. & Gershon, S. (1980). Differential effects of amphetamine and neuroleptics on negative vs. positive symptoms in schizophrenia. Psychopharmacology, 72 (1), 17-19.
11. Arseneault, L., Cannon, M., Witton, J. & Murray, R. (2004). Cannabis as a potential causal factor in schizophrenia. In D. Castle & R. Murray (Eds.), Marihuana and Madness: Psychiatry and Neurobiology. Cambridge: Cambridge University Press.
12. Baasher, T. A. (1980). The use of Khat: A stimulant with regional distribution. In G. Edwards & A. Arif (Eds.), Drug Problems in the Socio-Cultural Context (pp. 86-93). Geneva: WHO.
13. Balint, G. A., Ghebrekidan, H. & Balint, E. E. (1991). Catha edulis, an international socio-medical problem with considerable pharmacological implications. East African Medical Journal, 68 (7), 555-561.
14. Banjaw, M. Y., Miczek, K. & Schmidt, W. J. (2005). Repeated Catha edulis oral administration enhances the baseline aggressive behavior in isolated rats. Journal of Neural Transmission, 113 (5), 543-556.
15. Beck, A. T. & Steer, R. A. (1987). Beck Depression Inventory. San Antonio: The Psychological Corporation.
16. Belew, M., Kebede, D., Kassaye, M. & Enquoselassie, F. (2000). The magnitude of khat use and its association with health, nutrition and socio-economic status. Ethiopian Medical Journa, 38 (1), 11-26.
17. Bell, D. S. (1973). The experimental reproduction of amphetamine psychosis. Archives of General Psychiatry, 29 (1), 35-40.
18. Bhui, K., Abdi, A., Abdi, M., Pereira, S., Dualeh, M., Robertson, D, et al. (2003). Traumatic events, migration characteristics and psychiatric symptoms among Somali refugees: Preliminary communication. Social Psychiatry and Psychiatric Epidemiology, 38 (1), 35-43.
19. Bhui, K., Audini, B., Singh, S., Duffett, R. & Bhugra, D. (2006). Representation of asylum seekers and refugees among psychiatric inpatients in London. Psychiatric services: A Journal of the American Psychiatric Association, 57 (2), 270-272.
20. Brenneisen, R., Fisch, H. U., Koelbing, U., Geisshusler, S. & Kalix, P. (1990). Amphetamine-like effects in humans of the khat alkaloid cathinone. British Journal of Clinical Pharmacology, 30 (6), 825-828.
21. Brenneisen, R., Geisshusler, S. & Schorno, X. (1986). Metabolism of cathinone to (-)-norephedrine and (-)-norpseudoephedrine. The Journal of Pharmacy and Pharmacology, 38 (4), 298-300.
22. Calcagnetti, D. J. & Schechter, M. D. (1992). Increases in the locomotor activity of rats after intracerebral administration of cathinone. Brain Research Bulletin, 29 (6), 843-846.
23. Carothers, J. C. (1945). Miraa (Catha edulis) as a cause of psychosis. East African Medical Journal, 22, 4-6.
24. Carrier, N. (2005). »Miraa is cool«: the cultural importance of miraa (khat) for Tigania and Igembe youth in Kenya. Journal of African Cultural Studies, 17 (2), 201-218.
25. Carvalho, F. (2003). The toxicological potential of khat. Journal of Ethnopharmacology, 87 (1), 1-2.
26. Critchlow, S. & Seifert, R. (1987). Khat-induced paranoid psychosis. British Journal of Psychiatry: Journal of Mental Science, 150, 247-249.
27. CVS Consultants & Migrant and Refugee Communities Forum. (1999). A Shattered World: The mental health needs of refugees and newly arrived communities. London: CVS Consultants.
28. Date, J., Tanida, N. & Hobara, T. (2004). Qat chewing and pesticides: a study of adverse health effects in people of the mountainous areas of Yemen. International Journal of Environmental Health Research, 14 (6), 405-414.
29. Derogatis, L. R. (1977). SCL-90 Administration, Scoring and Procedure Manual. Baltimore: John Hopkins University Press.
30. Derogatis, L. R. & Melisaratos, N. (1983). The Brief Symptom Inventory: An introductory report. Psychological Medicine, 13 (3), 595-605.
31. Dhadphale, M. & Mengech, A. (1987). Letter to the Editor. British Journal of Psychiatry: Journal of Mental Science, 150, 876.
32. Dhadphale, M., Mengech, A. & Chege, S. W. (1981). Miraa (catha edulis) as a cause of psychosis. East African Medical Journal, 58 (2), 130-135.
33. Dhadphale, M. & Omolo, O. E. (1988). Psychiatric morbidity among khat chewers. East African Medical Journal, 65 (6), 355-359.
34. Dohrenwend, B. P., Shrout, P. E., Egri, G. & Mendelsohn, F. S. (1980). Nonspecific psychological distress and other dimensions of psychopathology. Measures for use in the general population. Archives of General Psychiatry, 37 (11), 1229-1236.
35. El-Kader, A. (1983). The Shariah's position on Khat. Paper presented at the International conference on Khat: The Health and Socio-Economic Aspects of Khat use, Antananaribo, Madagascar.
36. Elmi, A. S., Ahmed, Y. H. & Samatar, M. S. (1987). Experience in the control of khat-chewing in Somalia. Bulletin on Narcotics, 39 (2), 51-57.
37. Eriksson, M., Ghani, N. A. & Kristiansson, B. (1991). Khat-chewing during pregnancy-effect upon the off-spring and some characteristics of the chewers. East African Medical Journal, 68 (2), 106-111.
38. FAO. (2001). FAO/WFP crop and food supply assessment mission to Ethiopia - 9 January 2001. Special reports and alerts (GIEWS) Verfügbar unter: http://www.fao.org/documents/show_ cdr.asp?url_file=//DOCREP/004/X9320E/ X9320E00.HTM [02/03/2006].
39. Feyisa, T. & Aune, J. (2003). Khat expansion in the Ethiopian highlands. Effects on the farming system in Habro district. Mountain Research and Development, 23 (2), 186-190.
40. Fountain, J., McQuade, C., Peters, E., Anitha, S., Crompton, N., Roy, A.et al. (2004). Drug-related interventions for refugees and asylum seekers: a pilot study amongst Somali and Turkish communities in London. Lancaster: University of Lancashire, Faculty of Health, Centre for Ethnicity and Health.
41. Gebissa, E. (2004). Leaf of Allah: khat & agricultural transformation in Harerge, Ethiopia 1875-1991. Oxford, Athens: James Currey, Ohio University Press.
42. Geisshusler, S. & Brenneisen, R. (1987). The content of psychoactive phenylpropyl and phenylpentenyl khatamines in Catha edulis Forsk. of different origin. Journal of Ethnopharmacology, 19 (3), 269-277.
43. Giannini, A. J. & Castellani, S. (1982). A manic-like psychosis due to khat (Catha edulis Forsk.). Journal of Toxicology. Clinical Toxicology, 19 (5), 455-459.
44. Goldberg, D. P. & Hillier, V. F. (1979). A scaled version of the General Health Questionnaire. Psycholgical Medicine, 9 (1), 139-145.
45. Goudie, A. J. & Newton, T. (1985). The puzzle of drug-induced conditioned taste aversion: comparative studies with cathinone and amphetamine. Psychopharmacology (Berl), 87 (3), 328-333.
46. Gough, S. P. & Cookson, I. B. (1984). Khat-induced schizophreniform psychosis in UK. The Lancet, 25 (2), 455.
47. Granek, M., Shalev, A. & Weingarten, A. M. (1988). Khat-induced hypnagogic hallucinations. Acta psychiatrica Scandinavica. Supplementum., 78 (4), 458-461.
48. Griffiths, P. (1998). Qat use in London: a study of qat use among a sample of Somalis living in London. In C. D. P. Unit (Hrsg.) (Bd. Paper 26). London: Home Office.
49. Griffiths, P., Gossop, M., Wickenden, S., Dunworth, J., Harris, K. & Lloyd, C. (1997). Atranscultural pattern of drug use: qat (khat) in the UK. British Journal of Psychiatry, 170, 281-284.
50. Hafner, H., Riecher-Rossler, A., Hambrecht, M., Maurer, K., Meissner, S., Schmidtke, A. et al. (1992). IRAOS: an instrument for the assessment of onset and early course of schizophrenia. Schizophrenia Research, 6 (3), 209-223.
51. Halbach, H. (1972). Medical aspects of the chewing of khat leaves. Bulletin of the World Health Organization, 47 (1), 21-29.
52. Hambrecht, M. & Hafner, H. (1996). Substance abuse and the onset of schizophrenia. Biological Psychiatry, 40 (11), 1155-1163.
53. Harding, T. W., de Arango, M. V., Baltazar, J., Climent, C. E., Ibrahim, H. H., Ladrido-Ignacio, L. et al. (1980). Mental disorders in primary health care: a study of their frequency and diagnosis in four developing countries. Psychological Medicine, 10 (2), 231-241.
54. Hassan, N. A., Gunaid, A. A., Abdo-Rabbo, A. A., Abdel-Kader, Z. Y., al-Mansoob, M. A., Awad, A. Y. & Murray-Lyon, I. M. (2000). The effect of qat chewing on blood pressure and heart rate in healthy volunteers. Tropical Doctor, 30 (2), 107-108.
55. Hassan, N. A., Gunaid, A. A., El-Khally, F. M. & Murray-Lyon, I. M. (2002). The effect of chewing khat leaves on human mood. Saudi Medical Journal, 23 (7), 850-853.
56. Jablensky, A., Sartorius, N., Ernberg, G., Anker, M., Korten, A., Cooper, J. E. et al. (1992). Schizophrenia: manifestations, incidence and course in different cultures. A World Health Organization ten-country study. Psychological Medicine-Monograph Supplements, 20, 1-97.
57. Jager, A. D. & Sireling, L. (1994). Natural history of khat psychosis. The Australian and New Zealand Journal of Psychiatry, 28 (2), 331-332.
58. Janowsky, D. S. & Davis, J. M. (1976). Methylphenidate, dextroamphetamine, and levamfetamine. Effects on schizophrenic symptoms. Archives of General Psychiatry, 33 (3), 304-308.
59. Johanson, C. E. & Schuster, C. R. (1981). A comparison of the behavioral effects of I- and dl-cathinone and d-amphetamine. Journal of Pharmacology and Experimental Therapeutics, 219 (2), 355-362.
60. Kalix, P. (1987). Khat: scientific knowledge and policy issues. British Journal of Addiction, 82 (1), 47-53.
61. Kalix, P. (1990). Pharmacological properties of the stimulant khat. Pharmacology & Therapeutics, 48 (3), 397-416.
62. Kalix, P. (1991). The pharmacology of psychoactive alkaloids from ephedra and catha. Journal of Ethnopharmacology, 32 (1-3), 201-208.
63. Kalix, P. (1992). Cathinone, a natural amphetamine. Pharmacol Toxicol, 70 (2), 77-86.
64. Kalix, P. (1996). Catha edulis, a plant that has amphetamine effects. Pharmacy World & Science: PWS, 18 (2), 69-73.
65. Kay, S. R. (1991). Positive and negative syndromes in schizophrenia: assessment and research. New York: Brunner/Mazel.
66. Kebede, D., Alem, A., Mitike, G., Enquselassie, F., Berhane, F., Abebe, Y., Ayele, R., Lemma, W, Assefa, T. & Gebremichael, T. (2005). Khat and alcohol use and risky sex behaviour among in-school and out-of-school youth in Ethiopia. BMC Public Health, 5, 109.
67. Kennedy, J. G., Teague, J., Rokaw, W. & Cooney, E. (1983). A medical evaluation of the use of qat in North Yemen. Social Science & Medicine, 17 (12), 783-793.
68. Kennedy, J. G. (1987). The flower of paradise: the institutionalized use of the drug qat in North Yemen. Boston: D. Reidel Publishing Company.
69. Krikorian, A. D. (1983). Khat and its use: an historical perspective. Paper presented at the International conference on Khat: The Health and Socio-Economic Aspects of Khat Use, Antananaribo, Madagaskar.
70. Kristiansson, B., Abdul Ghani, N., Eriksson, M., Garle, M. & Qirbi, A. (1987). Use of khat in lactating women: A pilot study on breast-milk secretion. Journal of Ethnopharmacology, 21 (1), 85-90.
71. Lemessa, D. (2001). Khat (Catha edulis): Botany, Distribution, Cultivation, Usage and Economics in Ethiopia. Addis Ababa: UN-Emergencies Unit for Ethiopia.
72. Lipska, B. K., Halim, N. D., Segal, P. N. & Weinberger, D. R. (2002). Effects of reversible inactivation of the neonatal ventral hippocampus on behavior in the adult rat. The Journal of Neuroscience: The official Journal of the Society of Neuroscience, 22 (7), 2835-2842.
73. Litman, A., Levav, I., Saltz-Rennert, H. & Maoz, B. (1986). The use of khat. An epidemiological study in two Yemenite villages in Israel. Culture, Medicine and Psychiatry, 10 (4), 389-396.
74. Luqman, W. & Danowski, T. S. (1976). The use of khat (Catha edulis) in Yemen. Social and medical observations. Annals of Internal Medicine, 85 (2), 246-249.
75. Maitai, C. K. (1996). Catha edulis (miraa): a detailed review focussing on its chemistry, health implication, economic, legal, social, cultural, religious, moral aspects and its cultivation. Nairobi: National Council for Science and Technology.
76. McKee, C. M. (1987). Medical and social aspects of qat in Yemen: a review. Journal of the Royal Society of Medicine, 80 (12), 762-765.
77. McLaren, P. (1987). Khat psychosis. British Journal of Psychiatry, 150, 712-713.
78. Meampel, G. Z. (1992). The Arabian voyage of 1761- 67 and Malta: Forsskål and his contribution to the study of local natural history. Proceedings of History Week 1992, p. 35-76. The Malta Historical Society. Verfugbar unter: http://uk. geocities.com/davidmallia2000/Thierens/hw92fors.html [02/09/2006].
79. Mion, G., Ruttimann, M., Oberti, M. & Aversenq, C. (1997). [Acute Khat-induced psychotic crisis]. Annates francaises d'anesthesie et de reanimation, 16 (2), 201-202.
80. Mollica, R. F., Caspi-Yavin, Y., Bollini, P., Truong, T., Tor, S. & Lavelle, J. (1992). The Harvard Trauma Questionnaire. Validating a cross-cultural instrument for measuring torture, trauma, and post-traumatic stress disorder in Indochinese refugees. The Journal of Nervous and Mental Disease, 180 (2), 111-116.
81. Mueser, K. T., Drake, R. E. & Wallach, M. A. (1998). Dual diagnosis: a review of etiological theories. Addictive Behaviors, 23 (6), 717-734.
82. Nabuzoka, D. & Badhadhe, F. A. (2000). Use and perception of khat among young Somalis in a UK city. Addiction Research, 8 (1), 5-26.
83. Nencini, P. & Ahmed, A. M. (1989). Khat consumption: a pharmacological review. Drug and Alcohol Dependence, 23 (1), 19-29.
84. Nencini, P., Grassi, M. C, Botan, A. A., Asseyr, A. F. & Paroli, E. (1989). Khat chewing spread to the Somali community in Rome. Drug and Alcohol Dependence, 23 (3), 255-258.
85. Nielen, R. J., van der Heijden, F. M., Tuinier, S. & Verhoeven, W. M. (2004). Khat and mushrooms associated with psychosis. The World Journal of Biological Psychiatry: The official Journal of the World Federation of Societies of Biological Psychiatry, 5 (1), 49-53.
86. Nordal, A. (1980). Khat: pharmacognostical aspects. Bulletin on Narcotics, 32 (3), 51-64.
87. Nuechterlein, K. H., Dawson, M. E., Gitlin, M., Ventura, J., Goldstein, M. J., Snyder, K. S. et al. (1992). Developmental processes in schizophrenic disorders: longitudinal studies of vulnerability and stress. Schizophrenia Bulletin, 18 (3), 387-425.
88. Numan, N. (2004). Exploration of adverse psychological symptoms in Yemeni khat users by the Symptoms Checklist-90 (SCL-90). Addiction, 99 (1), 61-65.
89. Odenwald, M., Hinkel, H., Schauer, E., Neuner, F., Schauer, M., Elbert, T. et al. (submitted). Self-reported khat use and opinion about drug consumption among active military personnel in Somalia: a cross-sectional study.
90. Odenwald, M., Lingenfelder, B., Schauer, M., Neuner, F., Rockstroh, B., Hinkel, H. et al. (submitted). Screening for Post-traumatic Stress Disorder among Somali ex-combatants: A validation study.
91. Odenwald, M., Neuner, F., Schauer, M., Elbert, T. R., Catani, C., Lingenfelder, B., Hinkel, H., Hafner, H. & Rockstroh, B. (2005). Khat use as risk factor for psychotic disorders: A cross-sectional and case-control study in Somalia. BMC Medicine, 3 (1), 5.
92. Omolo, O. E. & Dhadphale, M. (1987). Alcohol use among khat (Catha) chewers in Kenya. British Journal of Addiction, 82 (1), 97-99.
93. Overall, J. E. & Goreham, D. R. (1962). The Brief Psychiatric Rating Scale. Psychological Reports, 10, 799-812.
94. Pantelis, C., Hindler, C. G. & Taylor, J. C. (1989). Use and abuse of khat (Catha edulis): a review of the distribution, pharmacology, side effects and a description of psychosis attributed to khat chewing. Psychological Medicine, 19 (3), 657-668.
95. Patel, S. L., Wright, S. & Gammampila, A. (2005). Khat use among Somalis in four English cities (Bd. Home Office Online Report 47/05): Home Office.
96. Pehek, E. A., Schechter, M. D. & Yamamoto, B. K. (1990). Effects of cathinone and amphetamine on the neurochemistry of dopamine in vivo. Neuropharmacology, 29 (12), 1171-1176.
97. Phillips, P. & Johnson, S. (2001). How does drug and alcohol misuse develop among people with psychotic illness? A literature review. Social Psychiatry and Psychiatric Epidemiology, 36 (6), 269-276.
98. Poole, R. & Brabbins, C. (1996). Drug induced psychosis. British Journal of Psychiatry: Journal of Mental Science, 168 (2), 135-138.
99. Robinson, T. E. & Becker, J. B. (1986). Enduring changes in brain and behavior produced by chronic amphetamine administration: a review and evaluation of animal models of amphetamine psychosis. Brain Research, 396 (2), 157-198.
100. Sato, M., Numachi, Y. & Hamamura, T. (1992). Relapse of paranoid psychotic state in methamphetamine model of schizophrenia. Schizophrenia Bulletin, 18 (1), 115-122.
101. Schechter, M. D. (1990a). Dopaminergic nature of acute cathine tolerance. Pharmacology, Biochemistry, and Behavior, 36 (4), 817-820.
102. Schechter, M. D. (1990b). Rats become acutely tolerant to cathine after amphetamine or cathinone administration. Psychopharmacology (Berl), 101 (1), 126-131.
103. Schopen, A. (1979). Qat im Jemen. In H. Gros (Hrsg.), Rausch und Realität: Eine Kulturgeschichte der Drogen (Bd. 2). Stuttgart: Ernst Klett Verlag.
104. Selassie, S. G. & Gebre, A. (1996). Rapid assessment of drug abuse in Ethiopia. Bulletin on Narcotics, 48 (1-2), 53-63.
105. Seyoum, E., Kidane, Y. & Gebru, H. (1986). Preliminary study of income and nutritional status indicators in two Ethiopian communities. Food and Nutrition Bulletin, 8 (3), 37-41.
106. Sheehan, D. V., Lecrubier, Y., Sheehan, K. H., Amorim, P., Janavs, J., Weiller, E.et al. (1998). The Mini-International Neuropsychiatry Interview (M.I.N.I.): the development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10. The Journal of Clinical Psychiatry, 59 Suppl 20, 22-33; quiz 34-57.
107. Szendrei, K. (1980). The chemistry of khat. Bulletin on Narcotics, 32 (3), 5-35.
108. Thompson, J. L., Pogue-Geile, M. F. & Grace, A. A. (2004). Developmental pathology, dopamine, and stress: a model for the age of onset of schizophrenia symptoms. Schizophrenia Bulletin, 30 (4), 875-900.
109. Thordstein, M., Jansson, T. & Kristiansson, B. (1991). Cerebral function of the guinea pig neonate after chronic intrauterine exposure to khat(Catha edulis Forsk.). Biology of the Neonate, 59 (3), 161-170.
110. Toennes, S. W., Harder, S., Schramm, M., Niess, C. & Kauert, G. F. (2003). Pharmacokinetics of cathinone, cathine and norephedrine after the chewing of khat leaves. British Journal of Clinical Pharmacology, 56 (1), 125-130.
111. U. N. (1971). Convention on Psychotropic Substances: United Nations.
112. UNODC. (1956). Khat. Bulletin on Narcotics, 8 (4), 6-12.
113. UNODC. (2004). World Drug Report 2004. New York: United Nations.
114. Ward, C. (2000). Yemen: CDR Qat. Washington, D. C: World Bank.
115. nd ed. (pp. 326-348). Oxford: Blackwell.
116. Weir, S. (1985). Qat in Yemen: consumption and social change. London: British Museum Publications Limited.
117. WHO. (1983). Report of the WHO intercountry meeting on the health, social and economic aspects of khat Mogadishu, 24-28 October 1983. Geneva: World Health Organization.
118. Widler, P., Mathys, K., Brenneisen, R., Kalix, P. & Fisch, H. U. (1994). Pharmacodynamics and pharmacokinetics of khat: a controlled study. Clinical Pharmacology and Therapeutics, 55 (5), 556-562.
119. Woolverton, W. L. & Johanson, C. E. (1984). Preference in rhesus monkeys given a choice between cocaine and d,l-cathinone. Journal of the Experimental Analysis of Behavior, 41 (1), 35-43.
120. Worldbank. (1999). Groundwater: Legal and Policy Perspectives; World Bank Technical Paper No. 456. Washington, D.C.: World Bank.
121. Worldbank. (2005). Yemen Economic Update, spring 2005. Sana'a: World Bank Sana'a Country Office.
122. Yanagita, T. (1986). Intravenous self-administration of (-)-cathinone and 2-amino-1-(2,5-dimethoxy-4-methyl) phenylpropane in rhesus monkeys. Drug and Alcohol Dependence, 17 (2-3), 135-141.
123. Yousef, G., Huq, Z. & Lambert, T. (1995). Khat chewing as a cause of psychosis. British Journal of Hospital Medicine, 54 (7), 322-326.
124. Yui, K., Ikemoto, S., Goto, K., Nishijima, K., Yoshino, T. & Ishiguro, T. (2002). Spontaneous recurrence of methamphetamine-induced paranoid-hallucinatory states in female subjects: susceptibility to psychotic states and implications for relapse of schizophrenia. Pharmacopsychiatry, 35 (2), 62-71.
125. Zein, A. (1988). Polydrug abuse among Ethiopian university students with particular reference to khat (Catha edulis). Journal of Tropical Medicine and Hygiene, 91, 71-75.
126. Zelger, J. L., Schorno, H. X. & Carlini, E. A. (1980). Behavioural effects of cathinone, an amine obtained from Catha edulis Forsk.: comparisons with amphetamine, norpseudoephedrine, apomorphine and nomifensine. Bulletin on Narcotics, 32 (3), 67-81.
127. Zubin, J., Magaziner, J. & Steinhauer, S. R. (1983). The metamorphosis of schizophrenia: from chronicity to vulnerability. Psychological Medicine, 13 (3), 551-571.