Drug addiction

The term drug dependence indicates a disorder of psychiatric interest classified in the Diagnostic statistical manual (DSM), edited by the American Psychiatric Association (APA), and in the International classification of diseases and health problems (ICD), edited by the World of health, in its tenth edition. The term drug addiction , which corresponds to the English addiction , is a synonym of f. reserved for the more serious forms. In English, an f is distinguished. in the strict sense ( drug-dependence ) from an f. for substances containing pharmacologically active ingredients, such as alcohol, tobacco, marijuana ( substance dependence). The F. is indicated by ICD 10 as a syndrome , i.e. a set of symptoms, of a physiological, behavioral and cognitive nature, in which the use of a substance or a class of psychoactive drugs acquires a much higher priority for the subject than other behaviors that previously they had a primary value. Fundamental aspect of addiction is the strong and compulsive craving) to consume the substance, the difficulty of moderating its use and the tendency to relapse into use even after a period of abstinence. Another important aspect of the f. it consists of tolerance and physical dependence, changes induced by chronic exposure to the drug. Tolerance consists of a progressive reduction in the efficacy of the drug so that increasing doses become necessary to maintain its pharmacological effects. Physical dependence is expressed in withdrawal, which develops when drug administration is stopped or replaced with a drug that antagonizes its effects. Tolerance and physical dependence are two aspects of an adaptation process and consist in the induction of modifications of opposite sign to those of the drug, which, in the presence of the drug itself, they reduce its effects (tolerance) and, in its absence, prevail, triggering the withdrawal syndrome. A classic example of tolerance and physical dependence is heroin and in general the analgesic narcotics of which morphine is the progenitor. Chronic exposure to these drugs induces tolerance to their analgesic, sedative, respiratory depressant and rewarding effects: their interruption causes an abstinence syndrome characterized by opposite symptoms (hyperalgesia, mydriasis, intestinal colic, diarrhoea, irritability). The importance attached to tolerance and physical dependence in f. has changed over the years. This evolution is also reflected in the criteria on which the diagnosis of addiction is based. Until 1987 tolerance and physical dependence were considered necessary conditions for a diagnosis of addiction. With the introduction of ICD-10 and 3In the R edition of the DSM, tolerance and physical dependence lose this status , becoming two of the 6 (ICD-10) or 7 (DSM) symptoms whose presence, in the measure of at least 3 of them, allows the diagnosis of drug dependence. The change corresponds to a reinterpretation of the meaning of the f. as a disturbance of motivation rather than as an alteration of drug response and organ functions, which is induced by chronic drug exposure.

The declassification of tolerance and physical dependence from prominent symptoms to symptoms equal to those of a motivational and psychological nature also derives from practical considerations. First of all from the awareness, deriving from the clinical experience accumulated with the diffusion of the use of base cocaine ( crack ), that not all f. they follow the model of analgesic narcotics or alcohol, products that induce a characteristic withdrawal syndrome. In fact, cocaine and amphetamines themselves produce a less defined and characteristic withdrawal syndrome. The same is true of cannabis and nicotine.

Another reason for this change is to be found in the decennial unsuccessful experience of attempts to cure f. from heroin or alcohol through cessation with a tapering treatment with drugs of the same class (e.g., methadone) or belonging to related drug classes (e.g., benzodiazepines, GHB). From this interpretative turning point derives the introduction in the diagnostic criteria of drug addiction, in addition to tolerance and physical dependence, of 4 (ICD-10) or 5 symptoms (DSM) indicative of the compulsion to use (strong desire to consume the drug , inability to control its use and to stop despite repeated attempts) and of the centrality of the drug in the subject's motivation (loss of motivation and interest in occupations, affections, social relationships not related to the drug; spends a large part of the time and possible involvement in illegal activities in order to procure the drug; continued use of the drug despite the onset of disorders and pathologies that are associated with drug dependence). Despite all this, the role of tolerance and physical dependence in f. it is not to be underestimated. DSM itselfiv invited us to distinguish two forms of f. depending on the presence of a component of a physiological nature, i.e. tolerance and physical dependence. Further studies show that for all the most important forms of f. (alcohol, cocaine, amphetamine, marijuana) the presence of tolerance and in particular (in the case of alcoholism) of physical dependence is associated with more serious forms and a less favorable prognosis. Related to the term drug addiction is abuse (of drugs and substances). The term is used by the DSM ivto indicate a less serious condition than f., which is characterized by the continued use of the drug or substance despite the fact that the subject is aware that this creates problems of a social, family, occupational and medical nature. The IC-10 does not use the term abuse but harmful to the health of the subject or risky from a social point of view. In the case of illicit substance use or illicit (non-therapeutic) use of licit drugs, the term abuse is often applied even in the presence of sporadic and non-continuous use.

Risk factors

The F. it is a typical example of interaction between genetic and environmental factors in which the influence of genetic factors is prevalent. Genetic epidemiology studies conducted on monozygotic and heterozygous twins show that genetic factors contribute between 63% and 78% of cocaine abuse. Similar percentages are obtained for other substances of abuse such as cannabis and caffeine itself (Kendler, Jacobson, Prescott et al. 2003). Unlike abuse and dependence, the mere use of substances is mainly determined by environmental rather than genetic factors. In the case of cocaine, use appears to depend only 39% on genetic factors and the rest on environmental factors. The same trendit is observed in the case of simple cannabis use . This dichotomy demonstrates the fundamental difference between the mechanisms underlying substance use and their abuse. Another important observation of the genetic epidemiology studies on twins is that the genetic factor which contributes to the abuse appears to be common to all abused substances, regardless of their dangerousness and addictive capacity and, therefore, regardless of whether be considered 'hard' or 'soft' drugs (Kendler, Jacobson, Prescott et al. 2003). Thus, no genetic factors specific to a specific class of drugs have been identified; on the contrary, drugs characterized by very different primary mechanisms of action, such as cannabisand cocaine or opiates, had a single genetic factor in common. Therefore, the genetic factors that in one group of individuals determine vulnerability to one class of drugs are the same ones that in another group of individuals contribute to the abuse of another class of drugs. These results indicate that addiction is largely determined by genetically transmissible constitutional factors common to all drugs. This conclusion is compatible with the notion that addiction is rarely restricted to a single substance, but often takes on the characteristics of polydrug abuse.. Furthermore, it is in agreement with the fact that the familiarity of substance abuse is not specific for one class of substances but extends to all those of abuse and is often associated with personality disorders and psychiatric disorders.

Personality and comorbidities

Personality can be represented as composed of two aspects, one invariant, present from childhood and of hereditary nature, the temperament, and the other acquired and dependent on experience and the environment, namely the character. In temperament there are a number of fundamental traits which, depending on the authors, take on different names. Various studies demonstrate a highly significant association between certain temperament traits and drug dependence. Of these traits, two are most frequently associated with anxiety, that of impulsivity/extroversion/seeking of new sensations or novelty ( sensation / novelty seeking) and that of neuroticism-anxiety/fear. For example, traits of impulsivity and neuroticism in children and adolescents were associated with alcoholism in adulthood. In addition, high rates of negative emotionality and behavioral disinhibition (impulsivity) have been shown to be predictive of substance abuse-related problems. Finally, various studies indicate a high association between alcoholism and sensation seeking. An aspect related to the association between specific personality traits and f. is the high degree of comorbidity existing between f., personality disorders as well as mental illnesses. The F. it is in fact frequently associated with antisocial personality disorder and conduct disorder, mood disorders (major depression, bipolar disorder) and anxiety disorders. This association can be explained as due to the fact that these conditions share a common causal factor. Alternatively, the psychic disturbance could induce f. as a form of self-medication, or f. could remove a psychic disturbance from the latency. Several studies regarding the argument show that the comorbidity of major depression and alcohol dependence is entirely explained by the comorbidity of both these conditions with antisocial personality disorder, which is also characterized by excessive impulsivity. An impulsivity disorder on genetic grounds could therefore be at the basis of the marked comorbidity between personality disorders, mood disorders, anxiety disorders and drug dependence.