Cannabis Use Disorder and Related Diagnoses

In order to situate cannabis use disorder and related diagnoses in context, it is first necessary to examine cannabis itself. Although knowledge of the drug and its culture is common, several important distinctions remain to be made. The following section provides a brief overview of the fundamentals of cannabis taxonomy, botany, pharmacology, nomenclature, preparation, and administration.

Taxonomy, Botany, and Pharmacology

Cannabis is the generic term for hemp, an annual that thrives in the world's temperate and tropical regions (Booth, 2003). While the exact geographic origin of cannabis is unknown, studies suggest it likely evolved in Central Asia, and not, as is popularly and mistakenly believed, in the Americas (Booth, 2003).

In 1753, Swedish botanist Carolus Linnaeus classified the hemp plant Cannabis sativa and ensconced it in the plant family Cannabinaceae (Booth, 2003; Earleywine, 2002; Roffman, Schwartz, & Stephens, 2006).

Thirty years after the taxonomic work of Linnaeus, the French naturalist Jean-Baptiste Lamarck differentiated between hemp grown in Europe and that grown in India, conferring the classification Cannabis indica upon the latter variety (Roffman et al., 2006). In 1924, a Russian botanist named Janischewski identified a third variety of hemp and classified it Cannabis ruderalis (Booth, 2003; Roffman et al., 2006). Uncertainty remains concerning whether these plant varieties are separate species or variations of one plant species, but the former interpretation has generally prevailed (Booth, 2003; Schultes, Klein, Plowman, & Lockwood, 1975).

Cannabis is botanically distinct. The stalk is angular, hollow, branched, and matted in fine hairs; the leaves are famously palmate and serrated (Booth, 2003). Cannabis, being dioecious, is individually male or female; however, both male and female plants produce a caramel-coloured resin (Booth, 2003). Redolent of peppermint and found throughout the plant, the resin is secreted by glandular hairs on the anthers of the male stamens and by the perianths of the female flowers and the leaves nearest them (Booth, 2003). The production of resin performs an as-yet-unknown primary function, although it has been theorized that the resin promotes the retention of water, protects seeds from ultraviolet radiation, and traps windswept pollen (Booth, 2003).

Cannabis is, of course, the source of a drug. Plants that contain psychoactive compounds are generally divided into two groups: psychotropic drugs, which affect the central nervous system, and psychotomimetic drugs (also known as hallucinogenic or psychedelic drugs), which alter human consciousness (Booth, 2003). Cannabis is of the latter category, but unlike most hallucinogenic botanicals, which are constituted chemically of alkaloids, the active ingredients of cannabis are uniquely non-nitrogenous substances called cannabinoids (Booth, 2003).

Of the approximately 460 known chemical constituents of cannabis, more than sixty have the molecular signature of a cannabinoid, but the most important of these is ?”9-tetrahydrocannabinol, more commonly known as THC, the primary psychoactive agent of cannabis (Turner, Bouwsma, Billets, & Elsholy, 1980). THC is a mild hallucinogen that in low doses produces a sense of euphoria, but in high doses produces a more powerful reaction in which perception is reconfigured (Booth, 2003). THC also serves as an analgesic, as a muscle-relaxant, as an antidepressant, and as an antiemetic agent (Booth, 2003). THC reduces epileptic fits, stimulates appetite, and dilates bronchial tissue (Booth, 2003). Most of the THC (and other cannabinoids) in a cannabis plant is synthesized in the resin-producing glands and concentrated in the resin itself (Booth, 2003).

The imbibement of THC produces a psychoactive "high." Per the DSM-5 (APA, 2013), the diagnostic features of cannabis intoxication include euphoria with inappropriate laughter and grandiosity, sedation, lethargy, impairment of short-term memory, difficulty carrying out complex mental processes, impaired judgment, distorted sensory perceptions, impaired motor performance, the sensation that time is passing slowly, and, occasionally, anxiety, dysphoria, or social withdrawal. In order to qualify as cannabis intoxication, the aforementioned diagnostic features must be accompanied by two or more of the following: conjunctival injection (red eyes), polyphagia (increased appetite), xerostomia (dry mouth), and tachycardia (APA, 2013).

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