GW is a British pharmaceutical firm that is growing cannabis and extracting its medically beneficial components for use in a sublingual spray. Note the criticisms of shoddy research on pot/mental illness and the larger number of references that indicate no relationship between pot use and mental illness. Now here's some real science:
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Mental Illness and Depression (GW Pharmaceuticals)
The use of cannabis by people with mental illness has historically been associated with claims of both benefits and harms (1, 2). In its recent review, the Institute of Medicine (3) observed (p. 106), ‘people with schizophrenia or with a family history of schizophrenia are likely to be at greater risk for adverse psychiatric effects from the use of cannabinoids,' and ‘there is little evidence that marijuana alone produces a psychosis that persists after the period of intoxication.'
In modern times, the suggestion that recreational cannabis use may be a risk factor for schizophrenia was first raised by Andreasson and collegeagues (4). Many of the other studies exploring this apparent association consist of retrospective analyses often relying on unreliable measures such as self-report, and are unable to distinguish association from causation. (5)(6)(7)(8). A recent retrospective and prospective examination of 232 newly diagnosed schizophrenic patients demonstrated no temporal correlation between substance abuse onset and that of psychosis (6). A recent review (7) concluded that cannabis may precipitate psychosis in vulnerable patients, increase relapse rates or produce dependency in those already affected. Similarly, in Italy (8), data supported a duality of experience such that some schizophrenics employ cannabis as self-treatment while in others it might be one factor predisposing to the disorder. It is noteworthy that endocannabinoid levels are elevated in the brains of schizophrenics (9), although the practical significance of this finding is not yet clear. The cannabis component cannabidiol may possess anti-psychotic activity (10), and a single case report was consistent with this (11).
Benefits were noted in depression measures in cancer patients treated with THC (12), and this has been supported by anecdotal reports (13). Both cannabidiol and nabilone (THC analogue) have demonstrated apparent benefit in clinical and experimental anxiety (10, 14, 15, 16). Anecdotal reports suggest that cannabis may alleviate symptoms of bipolar disease (17). The recent discovery that endocannabinoids regulate extinction of aversive memories (18) has led some to suggest the use of phytocannabinoids in treatment of post-traumatic stress disorder (PTSD).
References
1. Russo EB. Handbook of psychotropic herbs: A scientific analysis of herbal remedies for psychiatric conditions. Binghamton, NY: Haworth Press; 2001.
2. Grinspoon L, Bakalar JB. Marihuana, the forbidden medicine. Rev. and exp. ed. New Haven: Yale University Press; 1997.
3. Joy JE, Watson SJ, Benson JA, Jr. Marijuana and medicine: Assessing the science base. Washington, DC: Institute of Medicine; 1999.
4. Andreasson S, Allebeck P, Engstrom A, Rydberg U (1987). Cannabis and schizophrenia: a longitudinal study of Swedish conscripts. Lancet, ii, 1483 -86
5. Johns A. Psychiatric effects of cannabis. Br J Psychiatry 2001;178:116-22.
6. Buhler B, Hambrecht M, Loffler W, an der Heiden W, Hafner H. Precipitation and determination of the onset and course of schizophrenia by substance abuse--a retrospective and prospective study of 232 population-based first illness episodes. Schizophr Res 2002;54(3):243-51.
7. Degenhardt L, Hall W. Cannabis and psychosis. Curr Psychiatry Rep 2002;4(3):191-6.
8. Bersani G, Orlandi V, Kotzalidis GD, Pancheri P. Cannabis and schizophrenia: impact on onset, course, psychopathology and outcomes. Eur Arch Psychiatry Clin Neurosci 2002;252(2):86-92.
9. Leweke FM, Giuffrida A, Wurster U, Emrich HM, Piomelli D. Elevated endogenous cannabinoids in schizophrenia. Neuroreport 1999;10(8):1665-9.
10. Zuardi AW, Guimaraes FS. Cannabidiol as an anxiolytic and antipsychotic. In: Mathre ML, editor. Cannabis in medical practice: a legal, historical and pharmacological overview of the therapeutic use of marijuana. Jefferson, NC: McFarland; 1997. p. 133-141.
11. Zuardi AW, Morais SL, Guimaraes FS, Mechoulam R. Antipsychotic effect of cannabidiol . J Clin Psychiatry 1995;56(10):485-6.
12. Regelson W, Butler JR, Schulz J, Kirk T, Peek L, Green ML, et al. Delta 9-Tetrahydrocannabinol as an effective antidepressant and appetite- stimulating agent in advanced cancer patients. In: In: Braude MC, Szara S, ed. Pharmacology of marihuana. Vol 2. New York, Raven Press,; 1976. p. 763-776.
13. Russo EB, Mathre ML, Byrne A, Velin R, Bach PJ, Sanchez-Ramos J, et al. Chronic cannabis use in the Compassionate Investigational New Drug Program: An examination of benefits and adverse effects of legal clinical cannabis. Journal of Cannabis Therapeutics 2002;2(1):3-57.
http://www.cannabis-med.org/jcant/russo_chronic_use.pdf14. Zuardi AW, Cosme RA, Graeff FG, Guimaraes FS. Effects of ipsapirone and cannabidiol on human experimental anxiety. Journal of Psychopharmacology 1993;7(1):82-88.
15. Fabre LF, McLendon D (1981). The efficacy and safety of nabilone (a synthetic cannabinoid) in the treatment of anxiety. J Clin Pharm, 21, 377S-382S
16. Ilaria RL, Thornby JI, Fann WE (1981). Nabilone, a cannabinol derivative, in the treatment of anxiety neurosis. Current Therapeutic Research, 29, 943-9
17. Grinspoon L, Bakalar JB. The use of cannabis as a mood stabilizer in bipolar disorder: anecdotal evidence and the need for clinical research. J Psychoactive Drugs 1998;30(2):171-7.
18. Marsicano G, Wotjak CT, Azad SC, Bisogno T, Rammes G, Cascio MG, et al. The endogenous cannabinoid system controls extinction of aversive memories. Nature 2002;418(6897):530-4.