Clinical Textbook of Addictive Disorders 3rd ed - R. Frances, S. Miller, A. Mack (Guilford, 2005) WW

8. Marijuana, Hallucinogens, and Club Drugs 161mon in first-time users or in older experimenters who have not used marijuanafor a long time. Hypervigilance, sometimes resembling frank paranoia, is seenwith higher doses. Cannabis-induced psychosis is rare but does occur, especiallyin countries where heavy smoking is more common and the THC concentrationof the plant is higher (Chopra & Smith, 1974). The term “hemp insanity”refers to this type of psychosis. The question of whether the drug causes longtermpsychotic disorders is more difficult to answer. Clearly, first-break psychoticepisodes are commonly associated with marijuana ingestion, but again,whether they are causal is a matter of debate. More probably, individuals whoare prone to psychosis are attracted to the drug. In a population that is prone topsychosis, such as individuals with schizophrenia, marijuana is a risk factor forrelapse and psychosis (Arseneault, Cannon, Witton, & Murray, 2004; Verdoux,Gindre, Sorbara, Tournier, & Swendsen, 2003).Much has been written about the amotivational syndrome, and it hasremained a controversial entity (Lynskey & Hall, 2000). It is marked by apathy,poor concentration, social withdrawal, and loss of interest in achievements(Solowij, 1998). Because research in the topic is contradictory, it isunclear at this time whether marijuana induces amotivational attitudes andbehavior or causes permanent, irreversible impairment in cerebral function.However, the general consensus is that it likely does not cause permanentcognitive damage. Still, individuals who are chronic users tend to smoke marijuanaoften and in high doses; cannabis has a long half-life, and users can bethought to be chronically under the influence of marijuana or “stoned.” Somarijuana clearly causes impairment in the acquisition of short-term memory,at least for the time an individual is intoxicated, although there is evidenceof specific residual effects (Block, 1996; Pope & Yurgelun-Todd, 1996;Schwartz, 1991). If an individual, especially a young person, is “stoned”nearly all the time, his or her accumulation of knowledge will be seriouslyimpaired (Lynskey & Hall, 2000; Solowij, Michie, & Fox, 1995). If theintoxication continues long enough during critical growing time, it may havepermanent consequences. This is the most dangerous and insidious aspect ofmarijuana use. A high school student who is constantly “stoned” will notlearn to the degree to which he or she is capable of functioning. For manypeople, this will lead to a lifetime deficit that can never be completelyrepaired.TreatmentMarijuana withdrawal has been demonstrated in laboratory animals, as well asin humans, and is now well documented. Chronic heavy users of cannabis mayexperience some withdrawal in the form of irritability, general discomfort, disruptedsleep, and decreased appetite (Budney, Moore, Vandrey, & Hughes,2003). This syndrome is not as painful as that with heroin, as dangerous as that