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This introductory chapter begins with a description of the hemp plant from which the various cannabis products derive. The hemp plant (Cannabis sativa) may have originated in Central Asia but has been distributed widely around the world through man’s activities It has been cultivated as a multipurpose economic plant for thousands of years, and through the process of selection for various desirable characteristics, many different cultivated varieties exist—some growth for their fiber content, others for their psychoactive chemical content. The chapter then discusses the consumption of cannabis through smoking, eating, and drinking. A brief history of the drug is presented.

Humans use nearly every part of the infamous green weed Cannabis sativa. The plant grows quickly in many environments and can reach a height of 20 feet. The leaves consist of five or more narrow leaflets, each radiating from a slender stem attached to a thick, hollow stalk. The jagged edge of each leaflet resembles the blade of a serrated knife. The species is dioecious, meaning that both female and male varieties of the plant exist. The stalks help produce fiber; the seeds provide food and oil. The flowers, leaves, and resin appear in medical and intoxicating preparations. Each day, smiling teens buy hemp shirts. Retailers sell snacks made from the seed. Glaucoma patients puff cannabis cigarettes in hope of saving their sight, and many people worldwide inhale marijuana smoke in an effort to alter consciousness. These industrial, medical, and recreational uses for the plant go back thousands of years, contributing to its spread from Taiwan throughout the world. This chapter presents the histories of industrial hemp, medical marijuana, and cannabis.

Marijuana (cannabis) is among the most widely used of all psychoactive drugs. Despite the fact that its possession and use is illegal in many countries, cannabis is used regularly by as many as 20 million people in the United States and Europe and by millions more in other areas of the world. Thousands of patients with AIDS, multiple sclerosis, and a variety of other disabling diseases use marijuana in the firm belief that it makes their symptoms better, despite the relative paucity of medical evidence to substantiate this claim. This chapter reviews the long history of cannabis in human societies and its vilification and control in the 20th century. The plants Cannabis sativa and Cannabis indica are described, as are the various cannabis products derived from the plants and the more modern forms of concentrates.

Although cannabis has been used throughout human history, the scientific investigation of its effects only began with the isolation of THC in the 1960’s. Once discovered it was another 20 years before the mechanism by which THC produces its psychoactive effects in the brain, the CB₁ receptor, was discovered. Cannabis contains over 80 cannabinoid compounds, but THC is the only intoxicating compound. Recent preclinical research is being directed towards evaluating the therapeutic potential of other cannabinoid compounds found in cannabis, including CBD. The pharmacokinetics of THC, methods of administration, and dosing issues are explored in Chapter 1.

Dopamine is a neurotransmitter critical for reward processing and is elevated by most addicting drugs. The effect of THC and other CB₁ agonists moderately elevate dopamine in reward related regions of the rodent brain; however, there is less consistent evidence in humans for marijuana-induced changes in dopamine release or for morphological changes in brain reward areas. In humans, cannabis use disorder has been identified, which shows similar features of other substance use disorders, but not in the same extremes as opiates, psychostimulants or alcohol. This chapter discusses the interaction between cannabis and other drugs in relapse to drugs use, with a special case for the interaction between cannabinoids and opiates. Finally, the relationship between cannabinoid effects on men and women in sexual behaviour is discussed.

Was a search for drugs the main motivation that inspired travellers to go to the East? The chapter begins by considering one addict’s experience: however, the argument presented is that this was not typical. A historical contextualisation for drug-taking is given, noting how drugs of all sorts were often linked to Eastern cultures, even when there was no direct connection. Varied attitudes towards drug-taking are identified; in particular, the attitudes of an abstaining minority are considered. The chapter concludes by arguing that the existence of a wide range of considerably different attitudes to drug-taking means that drugs cannot be seen as a single, all-encompassing explanation for travel to the east.

Panic disorder is characterized by two components: recurrent panic attacks and anticipatory anxiety. Panic attacks within panic disorder are not caused by physical illness or certain substances and they are unexpected, at least initially; later in the course of the disorder, many attacks may be precipitated by certain situations or are more likely to occur in them. Anticipatory anxiety is an intense fear of having another panic attack, which is present between panic attacks. Some patients with panic disorder go on to develop agoraphobia, usually defined as fear and/or avoidance of the situations from which escape might be difficult or embarrassing or in which help might not be available in case of a panic attack; in such cases, patients are diagnosed with panic disorder with agoraphobia. Those who do not develop agoraphobia receive a diagnosis of panic disorder without agoraphobia. Components of panic disorder are presented in Figure 2—1. Patients with agoraphobia who have no history of panic disorder or whose agoraphobia is not related at least to panic attacks or symptoms of panic attacks are relatively rarely encountered in clinical practice. The diagnosis of agoraphobia without history of panic disorder has been a matter of some controversy, especially in view of the differences between American and European psychiatrists (and the DSM and ICD diagnostic and classification systems) in the conceptualization of the relationship between panic disorder and agoraphobia. The conceptualization adhered to here has for the most part been derived from the DSM system, as there is more empirical support for it. Although panic disorder (with and without agoraphobia) is a relatively well-defined psychopathological entity whose treatment is generally rewarding, there are important, unresolved issues. They are listed below and discussed throughout this chapter. …1. Are there different types of panic attacks based on the absence or presence of the context in which they appear (i.e., unexpected vs. situational attacks)? Should the ‘‘subtyping’’ of panic attacks be based on other criteria (e.g., symptom profile)? 2. Because panic attacks are not specific for panic disorder, should they continue to be the main feature of panic disorder? Can panic attacks occurring as part of panic disorder be reliably distinguished from panic attacks occurring as part of other disorders or in the absence of any psychopathology? 3. What is the relationship between panic attacks, panic disorder, and agoraphobia?

Social anxiety disorder (SAD) is conceptualized as an excessive and/or unreasonable fear of situations in which the person’s behavior or appearance might be scrutinized and evaluated. This fear is a consequence of the person’s expectation to be judged negatively, which might lead to embarrassment or humiliation. Typical examples of feared and usually avoided social situations are giving a talk in public, performing other tasks in front of others, and interacting with people in general. Although the existence of SAD as a psychopathological entity has been known for at least 100 years, it was only relatively recently, with the publication of DSM-III in 1980, that SAD (or social phobia) acquired the status of an ‘‘official’’ psychiatric diagnosis. The term social anxiety disorder has been increasingly used instead of social phobia, because it is felt that the use of the former term conveys more strongly the pervasiveness and impairment associated with the condition and that this term will promote better recognition of the disorder and contribute to better differentiation from specific phobia (Liebowitz et al., 2000). Like generalized anxiety disorder, social anxiety disorder is common and controversial. Unlike generalized anxiety disorder, which is described in different ways by different diagnostic criteria and different researchers and clinicians, SAD does not suffer from a ‘‘description problem.’’ It is not particularly difficult to recognize features of SAD; what may be difficult is making sense of these features. Main issues associated with SAD are listed below…. 1. Where are the boundaries of SAD? How well is SAD distinguished from ‘‘normal’’ social anxiety and shyness on one hand, and from severe psychopathology on the other? 2. Is there a danger of ‘‘pathologizing’’ intense social anxiety by labeling it a psychiatric disorder? How can the distress and suffering of people with high levels of social anxiety be acknowledged if they are not given the corresponding diagnostic label? 3. Is SAD a bona fide mental disorder? 4. Can the subtyping scheme (nongeneralized vs. generalized SAD) be supported? 5. Is there a spectrum of social anxiety disorders?

This chapter addresses all preclinical evidence supporting the potential of phytocannabinoids for the treatment of pain. Findings are reviewed with an emphasis on chronic pain since it is still often refractory to conventional pharmacotherapies and since there is mounting evidence that phytocannabinoids may be more efficacious in the treatment of chronic pain conditions rather than acute pain. The aim is to provide a summative review not only of the antinociceptive efficacy of the main phytocannabinoids when given alone but also of the preclinical data now available on these agents when they are administered in combination. In fact emerging evidence highlights greater beneficial effects of whole cannabis extracts than of single components of these extracts, justifying further exploration both of the therapeutic potential of cannabis-based medicines and of pharmacological interactions between some of its constituents. Finally, the molecular mechanisms that could explain phytocannabinoids-induced relief of chronic pain are fully discussed.

Sleep is a universal phenomenon that occurs in every species studied so far. A normal sleep period fluctuates in a regular cycle of two basic forms: slow wave sleep (SWS) and rapid eye movement (REM) sleep. The sleep–wake cycle is modulated by diverse brain circuits and neuromodulators as well as by several endogenous and exogenous molecules, including cannabinoids. This chapter describes the effects of certain cannabis-derived and synthetic cannabinoids on sleep. Additionally, it provides an overview of current knowledge about potential uses of natural or synthetic cannabinoids for the treatment of sleep disorders.

Chemical phenotypes (chemotypes) of Cannabis are defined by the content and composition of their cannabinoid fraction. This chapter describes the current diversity of chemotypes and discusses their underlying genetic mechanisms and breeding histories. The role of chemotype in Cannabis classification is addressed. Specific morphological features of the glandular trichomes associated with certain chemotypes are illustrated. The purity, content, and yield levels of the cannabinoids of clones selected in a plant-breeding program at GW Pharmaceuticals are presented. Several of these clones are currently in use for pharmaceutical raw material production. Their crude floral extracts and purified cannabinoids are being investigated for therapeutic potential. The chapter closes with some thoughts on the prospects of molecular breeding to modify cannabinoid biogenesis and further expand the cannabinoid portfolio

Methods of paleovegetation analysis can be grouped into two broad categories. Those that use plant microfossils for reconstructing terrestrial vegetation, past environments, migrations, and evolutionary histories constitute a part of paleopalynology that includes the study of pollen, spores, other acid-resistant microscopic structures, and phytoliths (distinctive, microscopic silicate particles produced by vascular plants). Those that use plant megafossils such as leaves, cuticles, cones, flowers, fruits, and seeds constitute paleobotany. Two important subdisciplines of paleobotany are dendrochronology (fossil woods) and analysis of packrat middens. The latter are sequences of nesting materials, constructed by packrats of the genus Neotoma, preserved in arid environments of the American southwest. The study of fossil fruits and seeds is a specialized field within paleobotany, and it is also used in studies on Quaternary vegetational history in the preparation of seed diagrams accompanying pollen and spore profiles from bog and lake sequences. In 1916 Swedish geologist Lennart von Post demonstrated that pollen grains and spores were abundantly preserved in Quaternary peat deposits and could be used to trace recent forest history and climatic change (Davis and Faegri, 1967). The term palynology was subsequently introduced by Hyde and Williams in 1944 to include all studies concerned with pollen and spores. Paleopalynology has come to denote the study of acid-resistant microfossils generally, while pollen analysis designates those investigations dealing specifically with the Quaternary. In the early 1950s researchers in the petroleum industry began to routinely apply paleopalynology to problems of stratigraphic correlation and the reconstruction of depositional environments in Tertiary and older strata (Hoffmeister, 1959). This added a practical dimension to a mostly academic pursuit and fostered interest in applied palynology and its use as a paleoecological research tool. This important development is reflected in the increased number of publications after about 1955. As the history of other innovations might predict, there was a period of exuberant claims, isolated specialization, and exaggerated charges of deficiency in the method; but for palynology this seemingly inevitable period was mercifully brief. The different terminology, principles, and techniques involved in megafossil paleobotany and paleopalynology still result in specialization, but this limitation is frequently overcome by coordinated or collaborative projects, and an increasing number of practitioners work in both disciplines.

No substance better exemplifies the ambivalence of Western societies toward psychoactive drugs than marijuana. In 2017, it was estimated that there were more than 22 million current users, about 6.7% of the adult population, in the United States. For those aged 18 to 25, the figure was nearly 20%. In the United Kingdom, the prevalence of recreational use of marijuana among males aged 16–34 was put at 15.5%. Despite its widespread acceptance, many regard marijuana as a serious drug of abuse which, if set free, will destroy the fabric of our society. Others see it as one of God’s gifts to humankind and regularly call for its legalization for medical use. By 2018, the United Kingdom and 40 other countries had heeded that call. In the United States, medical marijuana has been approved in 30 states and the District of Columbia with more sure to follow. Going further, recreational use is allowed in 10 of those states. Nonetheless, marijuana possession continues to be illegal under federal law in the United States, and some physicians have been threatened with loss of their licenses for advocating medical marijuana. In 2015, combined state and federal laws led to more arrests for possession of small amounts of marijuana than those for all violent crimes combined. The word marijuana (or the alternate spelling marihuana) does not appear in American medical texts of the 19th century. Instead, the term cannabis referred to flowering tops of the female plant of Cannabis sativa. At that time, while millions of persons in Asia and Africa habitually indulged in cannabis as an intoxicant, cannabis was little used for that purpose in this country. In this chapter, I will use the term “cannabis” to refer to any active material derived from Cannabis sativa and Cannabis indica, the two species—some say subspecies—of the plant. Today’s controversies surrounding “medical marijuana” often ignore its long history in European and American medicine. Beginning in 1850, Cannabis indica and several extracts of the plant were listed in The United States Pharmacopeia, an official compilation of medically useful drugs.

This chapter looks at cannabis products and their history in the nineteenth and twentieth centuries. In part this story is about the entry of preparations of the plant into Western medical knowledge and practice. However, the chapter also demonstrates that cannabis was not simply constructed as a medicine in Western circles in this period. The ways in which competing understandings emerged of the plant and the substances that could be manufactured from it is also explored. The purpose of doing this is twofold. In the first instance the chapter begins to provide some answers to the question of ‘what is medical about colonial medicine’. In addressing this question the chapter also addresses a second concern, which is to put plants back into the picture of the history of medicine in the colonial period.