Personality profile and drug of choice; a multivariate analysis using Cloninger’s TCI on heroin addicts, alcoholics, and a random population group
Introduction
Drug abuse or dependence results from a series of factors, including social and family issues, availability or fashion trends. Personality is another factor that may play an important role in the predisposition, precipitation or perpetuation of abuse or dependence behaviours. It is now generally agreed that individuals with substance-use disorders as a whole differ from controls on several broadly-defined personality dimensions (see later), but it is unclear to which degree of specificity these traits may be differentially linked to particular classes of substances. However, the study of links between personality and drug of choice is interesting in order to design optimal strategies in preventive care. And since personality may be associated with specific neurobiological mechanisms (Cloninger, 1987), it could also serve to better understand the complexities of addictive behaviours.
There is abundant literature on how to distinguish substance abusers or addicts from controls. Most studies in this field used dimensional scales focusing on specific aspects of personality rather than categorical divisions between normal patients and patients, such as in axis 2 of DSM-IV. Dimensional scales consider that a continuum is present between psychopathology and the normal range. Personality disorders are seen here as maladaptive extremes of normal personality dimensions.
The most salient variables that have been identified to characterize drug users in general are: (1) sensation seeking (SS; Zuckerman, 1974) and novelty-seeking, (NS; Cloninger, 1987). These (similar) concepts can be defined as: “the seeking of novel, intense, and complex forms of sensation and experience and the willingness to take risks for the sake of such an experience” (Zuckerman, 1994). It was found higher in several classes of addiction in comparison with controls (alcohol and tobacco: Masse and Tremblay, 1997; Ravaja and Keltikangas-Jarvinen, 2001; alcohol, nicotine and cannabis: Van Ammers et al., 1997; nicotine: Pomerleau et al., 1992; opiates: Vukov et al., 1995; cocaine: Ball et al., 1995; pathological gambling: Kusyszyn and Rutter, 1985); (2) impulsivity (IMP) was seen by Barratt (1990) as an “action on the spur of the moment” and is defined in the DSM-IV as “the failure to resist an impulse, drive, or temptation to perform an act that is harmful to the person or to others”. The concept is also one of the main tenets of Eysenck’s psychoticism scale (1968). Higher levels have been found in substance abusers than in the controls (alcohol: Heath et al., 1997, Cooper et al., 2000; tobacco: Patton et al., 1993, Mitchell, 1999; caffeine: Revelle et al., 1980). (3) Harm avoidance (HA) can be defined as the “tendency toward an inhibitory response to signals of aversive stimuli leading to avoidance of punishment and nonreward”. It is close to Eysenck’s Neuroticism concept (1968). In comparison with the controls, it was found lower in alcohol patients with early onset (Cloninger et al., 1988), with alcohol, tobacco and marijuana use in adolescents (Wills et al., 1994) and with the drinking frequency among adolescent psychiatric inpatients (Galen et al., 1997). In contrast, higher Shyness with Strangers (a sub-dimension of HA in the Cloninger model) has been found in moderate drinkers (de Wit and Bodker, 1994).
There are far fewer studies trying to differentiate between drug users of different types. Although the number of drugs used, whether stimulant or depressant, could be predicted by the SS scale (Zuckerman, 1983, Zuckerman, 1987, Moorman et al., 1989), in most cases the studies failed to predict drug of choice over personality variables. For instance, the Multiphasic Minnesota Personality Inventory (MMPI; Hathaway and McKinley, 1940) showed no profile difference between cocaine and marijuana users (Greene et al., 1993). No differential psychopathology or emotional disorders were found between users who take drugs from different classes (O’Connor and Berry, 1990). And personality similarities rather than differences between cocaine and heroin addicts were stressed by comparisons using DMS-III-R axis 2 and Millon Clinical Multiaxial Inventory (Craig and Olson, 1990).
A few papers, however, reported different personality profiles between specific drug users. Using the Tridimensional Personality Questionnaire (TPQ), a first design by Cloninger (1987), healthy non-addicts have been shown to prefer alcohol, diazepam and placebo as a function of personality traits, with ethanol-preferring subjects showing less Attachment (a sub-dimension of the Reward Dependence scale) than benzodiazepine-preferring ones (de Wit and Bodker, 1994). A relationship was found between the drug of choice and DSM-III co-morbid disorders, with cocaine users showing more cyclothymic disorders, and sedative-hypnotic abusers showing more Generalized Anxiety and Panic Disorders (Mirin et al., 1991). Using the Eysenck Personality Questionnaire (EPQ), one report showed opiate users to score higher than alcoholics in Susceptibility to Boredom (O’Connor et al., 1995). Using Tellegen’s multidimensional personality questionnaire (MPQ, 1985), opioid users were shown to score lower on constraint than alcoholics, which indicates more impulsivity in the former (Conway et al., 2002).
In the same study, a comparison between users of several different drugs showed the Constraint dimension of the MPQ to be decreased with the social deviance of the drug of choice (Conway et al., 2002). Opioid users and alcoholics showed the most opposite characteristics, so that these groups should be more easily distinguishable on the basis of personality questionnaires. Some differences between alcoholics and drug users, such as heroin can be expected from general observation and form the rationale for the present study. Since alcohol is a legal drug and heroin is not, the persons using the latter can be suspected to be more prone to ignore laws and rules, that is, to a more antisocial profile. This would be in line with the last two mentioned reports: (O’Connor et al., 1995, Conway et al., 2002). Also, as alcohol is more often used than illegal drugs to reduce stress, alcoholics can also be hypothesized to have “weaker” personalities, that is, to be more avoidant of danger and less “responsible” than other substance users. Given their usually more marginal style of living, heroin users could also have a less efficient capacity for reality-testing than alcoholics.
To compare these traits in a homogeneous way, it was important to use a global construct where factors are clearly isolated. Cloninger’s biosocial model (Cloninger et al., 1993) offers such a structure. It also presents the advantage to combine the hypothesized genetic and neurobiological bases of personality (temperament) with their interaction with learning and environment (character). This contrasts with a model, such as Eysenck, 1967, Eysenck, 1990, which bases personality almost exclusively on biology.
The present study compared a group of specific heroin addicts, a group of alcoholics and a healthy control group. An antisocial profile (main hypothesis) should be translated into a higher degree of Exploratory Excitability, more Impulsiveness (both sub-dimensions of NS) and less HA than normal users or abstainers. The “weaker” personality of alcoholics suggests more HA and less Self-Directedness (SDT) than heroin users (second hypothesis). A looser reality-testing capacity of the heroin users may indicate more Self-Transcendence (third hypothesis). The other TCI dimensions were studied here descriptively, in order to help elucidate the structure into which these addiction-associated personality variables are embedded.
Section snippets
Subjects
A total of 42 patients with heroin dependence (mean age 31.2; SD: 5.5; 10 females), 37 patients with alcohol dependence (mean age 44.2; SD: 9.1; 9 females) and 83 subjects from a random population sample (mean age: 38.8; SD: 6.9; 20 females) were entered in the multivariate analysis.
The Brugmann University Hospital welcomes heroin-dependent patients under a methadone maintenance program, who are seeking detoxification under anaesthesia (Ultra Rapid Opiate Detoxification). Inclusion criteria
Results
A total of 42 patients with heroin dependence, 37 patients with alcohol dependence and 83 subjects from a random population sample were entered in the multivariate analysis.
MANCOVA Pillai’s Trace was 3265; df: 50; P<0.0001 for subject group; the analysis was not significant for age. Only spiritual acceptance showed a significant interaction between group and gender (P=0.017), so that results for this sub-dimension should be taken with caution. Results of univariate ANCOVAs for the total sample
Discussion
This comparison between two dependent patient groups (heroin and alcohol) and a general population sample showed the two pathological conditions globally to deviate in the same direction with respect to controls. Both showed more novelty-seeking, less self-directedness and more self-transcendence than the controls. Higher levels of SS in the addict groups than in the controls were previously demonstrated (Malatesta et al., 1981, Cloninger et al., 1988, Galen et al., 1997; Ravaja and
Acknowledgements
This work was supported by a SOMALCPE grant (Brussels), a private institution exclusively dedicated to research in psychiatry. SOMALCPE stands for SOMMEIL (sleep), ALCOOL (alcohol) and PERSONNALITE (personality). The authors wish to thank Ms Jennifer Valcke who carefully checked for English accuracy.
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