SUBSTANCE USE DISORDERS: DEPENDENCE AND ABUSE
Nicotine and cigarettes. Nicotine, the main alkaloid of tobacco, is the agent which produces dependence. It stimulates the nicotine receptors located in the cerebral ‘pleasure centres’. According to some studies carried out by the Ministry of Health of the United States, tobacco kills more Americans than AIDS, road accidents, cocaine, heroin and cases of murder and suicide put together (Shultz, 1991). The children of smokers have a greater risk of suffering from affections of the upper respiratory tracts, bronchitis and auricular infections than individuals of the same age whose parents do not smoke. The health risks however are significantly lower for pipe and cigar-smokers as they only rarely inhale smoke into their lungs but these types of smoking habits increases the risk of developing cancer of the mouth. Amongst medical problems associated with the habit of smoking cigarettes and which, almost certainly, are caused or exacerbated by it, the most significant include cancer of the lungs, emphysema, cancer of the larynx and oesophagus and various cardiovascular diseases. After quitting smoking, the risks of disease decrease drastically over the subsequent 5-10 years until levels only slightly higher than those of non-smokers are eventually reached, however the destruction of pulmonary tissue is irreversible (Jaffe, 1985). A further important aspect of the phenomenon of smoking cigarettes is passive smoking. Smoke from a lit cigarette spreads in the atmosphere and is also breathed in by non-smokers. The latter may suffer from pulmonary damage, which may also be permanent, following prolonged exposure to cigarette smoke. Many non-smokers cannot stand the smell of burning tobacco, which in certain cases may cause allergic reactions.
Marijuana. This substance is obtained from the processing of Cannabis Sativa and can be smoked, chewed, drunk as an infusion or consumed through eating oven-baked products. Hashish, which is much stronger than marijuana, is also produced from Cannabis Sativa by means of a different type of process. The intoxicating effects of these two substances partly depend on their concentration and dosage. Marijuana smokers find that the substance makes them feel relaxed and sociable and it has been referred that high doses produce rapid alterations at the emotional level, reduce the level of attention, cause difficulty in complex mental processing and compromise the memory. Hallucinations and panic attacks are also possible. Laboratory studies conducted during the 1960s in particular have highlighted the fact that marijuana interferes with a wide range of cognitive functions including the memory. Intoxication also undermines the complex psychomotor skills required to drive a vehicle. In a more recent study, it emerged that the use of marijuana and hashish during adolescence contributes towards the insurgence of psychological problems in adulthood (Kandel and other, 1986). Such substances also generate numerous short-term somatic effects, including bloodshot and irritated eyes, dryness of the mouth and throat and an increase in appetite. The heartbeat may also be considerably accelerated, which may represent a source of risk in subjects that present an already altered cardiac functionality.
Sedatives. Also known as tranquillizers, these substances slow down the general functioning of the organism and reaction times. Sedatives include opiates (opium and its derivatives: morphine, heroin and codeine), barbiturates and tranquillizers. Opiates are a group of sedatives that produce dependence and in moderate doses alleviate pain and induce sleep. The most important is opium, from which are derived morphine and heroin. These substances produce states of euphoria, sleepiness, reveries and daydreaming and occasionally a deficit in coordination. Opiates produce their effect by stimulating the neural receptors of the endogenous opioid system of the organism. The human organism produces opioids called endorphins and encephalins and opium and its derivatives adapt to their receptors, stimulating them. They induce dependence and tolerance or, in other words, an increase in the quantity of substance tolerated by the organism. Abstinence leads to muscular pain, repeated sneezing, sweating, lacrimation (secretion of tears) and frequent yawning. The symptoms are similar to those that would appear in a person suffering from influenza, however after about 36 hours of abstinence they get worse. Uncontrollable muscular conditions may also appear such as cramps, cold shivering alternated with hot flushes, tachycardia and an increase in blood pressure. These symptoms last for about 72 hours and then gradually subside.
Barbiturates. These are synthetic sedatives and are used to induce and facilitate sleep. They relax the muscles, lower anxiety and in small doses produce a slight degree of euphoria. If used in high doses, they generate indistinct speech and a difficulty in maintaining one’s balance. People who use these substances lose control over their emotions and may become irritable and aggressive before falling into a deep sleep. Very high doses may be lethal as this would relax the diaphragmatic muscle to an excessive degree, thereby causing suffocation. The effects of abstinence last for many days and can also cause sudden death.
Amphetamines. These drugs produce their effect stimulating the release of noradrenaline and dopamine (see glossary). They may induce dependence and reduce the need for sleep, inhibit intestinal functions and reduce the sensation of hunger. They increase the heart rate, cause vigilance, euphoria and extraversion, and increase the individual’s level of energy and resistance. Individuals who consistently use these substances often become suspicious and hostile, and to such an extent they may become dangerous for others. Massive doses absorbed over long periods generate a state comparable with that presented in schizophrenia of the paranoid type. The state of great energy which they produce is moreover replaced by complete psycho-physical exhaustion when the effect wears off.
LSD and other hallucinogens: LSD is a chemical, laboratory-produced substance defined as a hallucinogenic on account of the effects it produces. It induces hallucinations of various kinds and other sensations such as synaesthesia (see glossary) but to a large extent its effects depend on individual psychological variables. It is believed that the overall psychological situation of the individual - that is, the subject’s attitudes, expectations and motivations concerning the use of drugs - is a determining factor as regards his or her reaction to the substance. The main dangers deriving from use of this substance include the possibility of suffering an extremely negative mental experience (a so-called ‘bad trip’), which may assume the characteristics of a panic attack. A minority of individuals will enter into a psychotic state requiring hospitalization and prolonged treatment. Other hallucinogenic drugs include mescaline, psilocybin, MDA and MDMA (the so-called ‘designer drugs’).
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