Five-factor model personality traits in opioid dependence
© Kornør and Nordvik; licensee BioMed Central Ltd. 2007
Received: 30 April 2007
Accepted: 06 August 2007
Published: 06 August 2007
Personality traits may form a part of the aetiology of opioid dependence. For instance, opioid dependence may result from self-medication in emotionally unstable individuals, or from experimenting with drugs in sensation seekers. The five factor model (FFM) has obtained a central position in contemporary personality trait theory. The five factors are: Neuroticism, Extraversion, Openness to Experience, Agreeableness and Conscientiousness. Few studies have examined whether there is a distinct personality pattern associated with opioid dependence.
We compared FFM personality traits in 65 opioid dependent persons (mean age 27 years, 34% females) in outpatient counselling after a minimum of 5 weeks in buprenorphine replacement therapy, with those in a non-clinical, age- and sex-matched sample selected from a national database. Personality traits were assessed by a Norwegian version of the Revised NEO Personality Inventory (NEO PI-R), a 240-item self-report questionnaire. Cohen's d effect sizes were calculated for the differences in personality trait scores.
The opioid-dependent sample scored higher on Neuroticism, lower on Extraversion and lower on Conscientiousness (d = -1.7, 1.2 and 1.7, respectively) than the controls. Effects sizes were small for the difference between the groups in Openness to experience scores and Agreeableness scores.
We found differences of medium and large effect sizes between the opioid dependent group and the matched comparison group, suggesting that the personality traits of people with opioid dependence are in fact different from those of non-clinical peers.
Opioid dependence is a severe condition associated with substantial psychological, social and medical impairment, as well as poor treatment outcomes. The aetiology of opioid dependence is not quite established. We believe a number of aspects are involved, including biological, psychological and socioeconomic factors [1, 2].
According to the self-medication hypothesis [3–5], emotionally unstable individuals may experience that their psychological distress is alleviated when they use opioids. In that respect, using opioids can be seen as a response in a negative reinforcement process [6, 7] – it removes an aversive stimulus (psychological distress), reinforcing the response (increased tendency to use opioids).
Opioid use has also been associated with sensation seeking and engagement in risk behaviours [8–10]. Zuckerman views sensation seeking as a personality trait with biological foundations, making some people more inclined to engage in risk behaviours than others .
The five-factor model (FFM) [12, 13] of personality is a conceptualisation of personality comprising behavioural, emotional and cognitive patterns. These patterns are thought of as enduring dispositions which have proved to be stable from the age of 30 [14, 15]. Also, the FFM has been reproduced in a number of culturally different countries [16–18], indicating a universally valid structure. The FFM has a hierarchical structure; each of the five domains Neuroticism, Extraversion, Openness to experience, Agreeableness and Conscientiousness is defined by six subdomains, or facets.
Studies of relationships between FFM dimensions and mental health indicate that people with psychiatric disorders have distinct personality patterns [19–22]. One meta-analysis found a general pattern of high Neuroticism, low Conscientiousness, low Agreeableness and low Extraversion in people with clinical symptoms . Another meta-analysis identified high Neuroticism and low Agreeableness as underlying dimensions of most personality disorders . People with various substance use disorders also seem to have a common personality profile: high Neuroticism, low Conscientiousness and low Agreeableness [23–29].
Two US studies have examined FFM personality traits in people with opioid dependence. Personality patterns were consistent with those of people with psychiatric and of people with substance use disorders, i.e. high Neuroticism, low Conscientiousness and low Agreeableness [30, 31]. At the subdomain level, the largest deviations from norm scores were seen in Neuroticism facets Depression and Vulnerability, Agreeableness facets Trust and Straightforwardness, and Conscientiousness facets Competence, Dutifulness, Achievement Striving and Self-Discipline.
To these authors' knowledge there are no studies on the relationships between FFM personality traits and opioid dependence conducted outside the USA. Studies from other countries are needed to supplement US studies and the understanding of the origins and consequences of dependent opioid use. The aim of this study was to examine whether there is a distinct personality pattern associated with opioid dependence in young Norwegian adults, when compared with an age- and sex-matched non-clinical comparison group.
Opioid dependent sample
The opioid dependent sample was 65 participants in a feasibility trial of short-term buprenorphine replacement therapy in 2002–2003 [32, 33]. Inclusion criteria in the feasibility trial were: age ≥ 22 years, opioid dependence diagnosed with the Composite International Diagnostic Interview , and enrolled in one of five specific outpatient clinics in South Eastern Norway. Persons with severe medical or psychiatric conditions or who had a prison sentence pending were excluded because they would be unable to adhere to the study protocol.
Illicit substance use last 30 days prior to intake to trial for opioid dependent sample
A minimum of 5 weeks after buprenorphine induction, when assumed to have achieved a stable state, patients were requested to complete the NEO-PI-R at the clinics. Instructions were given both verbally and in writing, and clinic staff was available for answering any questions regarding the inventory. Approvals were granted from the Regional Committee for Medical Research Ethics, Norwegian Medicines Agency and the Data Inspectorate. All participants were informed both orally and in writing about the study, and signed informed consent forms.
Matched comparison group
For each opioid dependent participant a comparison person with matching age and sex was randomly drawn from a national data base containing scores of 1153 individuals representing a wide range of the general Norwegian population. Individuals with known psychiatric disorder were removed from the database. Data from the comparison group were collected consecutively in various settings over a number of years (1998–2001). Thirty-two (49%) were graduate students and 20 (31%) were professionals. For the remaining comparison group we only know that 10 (15%) were participants in studies of physical activity or monozygotic twins.
The Norwegian version of the NEO-PI-R  was used for FFM personality trait assessments. Each individual's T-scores (mean = 50, SD = 10) were calculated on the basis of national combined norms.
Analyses were conducted using the statistical package SPSS for Windows, version 11.0 . Cohen's d effect sizes  were calculated for the differences in T-scores between opioid dependent subjects and controls. Statistical power calculations showed that the sample size allowed the detection of a difference of a medium effect size (d ≥ 0.50) at the 0.01-level with power > 0.8.
Domain and facet level T-scores for opioid dependent sample and comparison sample
Opioid dependent sample (N = 65)
Comparison sample (N = 65)
95% confidence interval
OPENNESS TO EXPERIENCE
Openness to Experience facets
In the opioid dependent sample there were several deviations with medium (d ≥ 0.50) or large (d ≥ 0.80) effect sizes from the comparison group mean scores (Table 2):
• higher scores on Neuroticism and facets Anxiety, Angry Hostility, Depression, Self-Consciousness and Vulnerability
• lower scores on Conscientiousness and all facets
• lower scores on Extraversion and facets Warmth, Gregariousness, Assertiveness, Activity and Positive Emotions.
Moreover, the opioid dependent sample had lower scores on Agreeableness facets Trust and Straightforwardness. There were no medium or large effect sizes for any of the differences in Openness to Experience facets, except for Openness to Values (d = 0.51).
Almost half the opioid dependent sample (29; 45%) scored above the comparison sample's 95th percentile on Neuroticism (T-score ≥ 63.95). Corresponding frequencies of extreme scorers (below the 5th percentile) were 26%, 19%, 3% and 2% for Conscientiousness (T-score ≤ 29.93), Extraversion (T-score ≤ 33.11), Openness to Experience (T-score ≤ 31.18) and Agreeableness (T-score ≤ 28.44), respectively. When the 75th and 25th percentiles were used as cut-offs for extreme scorers, the frequencies were 88% for Neuroticism (T-score ≥ 55.67), 83% for Conscientiousness (T-score ≤ 45.12), 72% for Extraversion (T-score ≤ 46.99), 43% for Agreeableness (T-score ≤ 44.02) and 29% for Openness to Experience (T-score ≤ 42.05).
The Norwegian opioid dependent sample resembled the US ones [30, 31] in terms of high Neuroticism, low Conscientiousness and average Openness to Experience. There were also dissimilarities between Norwegian and US findings: low Extraversion in Norwegian opioid users and no difference in Agreeableness between the opioid dependent and the comparison group.
Both this and the US studies of opioid dependent samples confirmed other research observations of high Neuroticism and low Conscientiousness in substance use disorders, across nationalities, sample age (US samples were older than the Norwegian one) and type of substances used (US participants were frequently co-dependent on cocaine). High Neuroticism in people with substance dependence can be seen as consistent with the self-medication hypothesis: people use and become dependent on opioids because they are emotionally unstable. However, we do not yet know the direction of causality, or whether one causes the other at all. Low Conscientiousness may be a common denominator for opioid use, risk behaviours and sensation seeking. Opioid users appear to share the low levels of Conscientiousness with people with risky health behaviours [30, 38–41], and risk behaviours have been associated with sensation seeking .
The lack of differences between the two groups in Openness to Experience was also supportive of earlier work, suggesting that a person's degree of conventionality and adherence to traditions is unrelated to opioid dependence.
It is difficult to explain the low Extraversion in Norwegian opioid users. One approach is to see the high prevalence of psychiatric disorders in this sample in relation to previous studies showing strong associations between pure mood, anxiety or psychotic disorders and low Extraversion . More knowledge about the mental health state in the US opioid dependent samples would of course shed light to such an approach.
Despite a lacking relationship between opioid dependence and Agreeableness at the domain level we found deviations that were consistent with US findings at the facet level. People with opioid dependence seem to be less trusting and less straightforward than the norm in both countries. Further, we calculated Cohen's d for Agreeableness in one of the US samples , which was 0.7, i.e. medium effect size. The correspondent Norwegian d was 0.49, i.e. approaching medium effect size. The apparent deviation in the Norwegian and US findings regarding Agreeableness may be a statistical artefact related to sample size. Further, while high Neuroticism and low Conscientiousness are consistent elements in substance use disorder personality profiles across studies [23, 25–29], there are examples of studies where low Agreeableness failed to emerge [24, 26, 28], indicating a weaker association.
A limitation of this study is that we do not know to what extent participants were under the influence of illicit drugs when completing the personality inventory. In Carter and colleagues' study, all participants tested positive for illicit opioids or other drugs at the first administration of the NEO-PI-R, and 75% were using illicit substances during the second administration . We did not administer the NEO-PI-R until the sixth week of buprenorphine replacement therapy, when patients were assumed to have achieved stability with regard to substance use. Data from the feasibility trial show that this assumption was rather reasonable. Assessments 3 months after the first buprenorphine dose showed that substance use was modest and significantly reduced since inclusion assessments .
There is also a possibility that both buprenorphine replacement therapy and counselling may have influenced the opioid dependent participants' personality trait scores. In that case we would expect even higher Neuroticism and lower Conscientiousness at intake to the feasibility trial and even more homogeneity in terms of high frequencies of extreme scores. Piedmont and colleagues found persisting changes in Neuroticism, Conscientiousness and Agreeableness in a sample with substance use disorders after a 6-week counselling programme .
Further, our study design can only identify associations with unknown causal directions. On one hand, the opioid dependent sample's distinct personality profile could be understood as part of the aetiology of opioid dependence. Several investigations have documented that personality traits are remarkably stable [14, 15, 43], that they have a significant hereditary component , and that they have behavioural implications, i.e., they influence behavior in any situation and they contribute to decisions on which situations individuals are motivated to enter and participate in . On the other hand, the opioid-dependent sample's personality profile could be explained by a shared, distinctive lifestyle associated with long-term substance use. There is evidence suggesting that personality traits are less stable in younger adults than older adults , and thus more susceptible to external influences.
The five-factor model of personality has obtained a central position in contemporary personality trait theory. The impact of group personality profiles have been examined in several fields, including occupational psychology and mental health. Merely describing the personality characteristics of individuals with opioid dependence is not enough. We need to know more about how personality traits influence prognosis. It could also be useful to model treatment programmes using knowledge of the group's typical personality profile, and evaluating the effectiveness of such programmes compared to standard treatment.
Patients with opioid dependence were more emotionally unstable, more introverted and less structured than the non-clinical controls. These findings may represent risk factors for opioid dependence, but may also be results of the lifestyles of illicit substance users. Nevertheless, the distinct personality profiles of opioid dependent patients may have implications for choice of therapeutic approach.
- Connock M, Juarez-Garcia A, Jowett S, Frew E, Liu Z, Taylor R, Fry-Smith A, Day E, Lintzeris N, Roberts T, et al: Methadone and buprenorphine for the management of opioid dependence: A systematic review and economic evaluation. Birmingham. 2006Google Scholar
- Dervaux A, Krebs MO: Vulnerability in heroin dependence. Ann Med Psychol (Paris). 2004, 162: 307-310.View ArticleGoogle Scholar
- Khantzian EJ: The self-medication hypothesis of substance use disorders: A reconsideration and recent applications. Harv Rev Psychiatry. 1997, 4: 231-244.View ArticlePubMedGoogle Scholar
- Markou A, Kosten TR, Koob GF: Neurobiological similarities in depression and drug dependence: A self-medication hypothesis. Neuropsychopharmacol. 1998, 18: 135-174. 10.1016/S0893-133X(97)00113-9.View ArticleGoogle Scholar
- Khantzian EJ: The Self-Medication Hypothesis of Addictive Disorders – Focus on Heroin and Cocaine Dependence. Am J Psychiatry. 1985, 142: 1259-1264.View ArticlePubMedGoogle Scholar
- Passer MW, Smith RE: Psychology. The science of mind and behavior. 2004, New York: McGraw-HillGoogle Scholar
- Adams JB, Heath AJ, Young SE, Hewitt JK, Corley RP, Stallings MC: Relationships between personality and preferred substance and motivations for use among adolescent substance abusers. Am J Drug Alcohol Abuse. 2003, 29: 691-712. 10.1081/ADA-120023465.View ArticlePubMedGoogle Scholar
- Liraud F, Verdoux H: Which temperamental characteristics are associated with substance use in subjects with psychotic and mood disorders?. Psychiatry Res. 2000, 93: 63-72. 10.1016/S0165-1781(99)00120-1.View ArticlePubMedGoogle Scholar
- Kosten TA, Ball SA, Rounsaville BJ: A Sibling Study of Sensation Seeking and Opiate Addiction. J Nerv Ment Dis. 1994, 182: 284-289. 10.1097/00005053-199405000-00006.View ArticlePubMedGoogle Scholar
- Scourfield J, Stevens DE, Merikangas KR: Substance abuse, comorbidity, and sensation seeking: Gender differences. Compr Psychiatry. 1996, 37: 384-392. 10.1016/S0010-440X(96)90021-8.View ArticlePubMedGoogle Scholar
- Zuckerman M: Psychobiology of personality. 2005, New York: Cambridge University PressView ArticleGoogle Scholar
- Digman JM: Personality Structure: Emergence of the 5-Factor Model. Annu Rev Psychol. 1990, 41: 417-440.View ArticleGoogle Scholar
- Costa P, McCrae R: Revised NEO Personality Inventory (NEO PI-R) and NEO Five-Factor Inventory (NEO-FFI). 1992, Odessa, FL: Psychological Assessment ResourcesGoogle Scholar
- Costa J, McCrae RR: Personality in Adulthood: A Six-Year Longitudinal Study of Self-Reports and Spouse Ratings on the NEO Personality Inventory. J Pers Soc Psychol. 1988, 54: 853-863. 10.1037/0022-3518.104.22.1683.View ArticlePubMedGoogle Scholar
- Terracciano A, Costa PT, McCrae R: Personality plasticity after age 30. Pers Soc Psychol B. 2006, 32: 999-1009. 10.1177/0146167206288599.View ArticleGoogle Scholar
- McCrae RR, Costa J: Personality Trait Structure as a Human Universal. Am Psychol. 1997, 52: 509-516. 10.1037/0003-066X.52.5.509.View ArticlePubMedGoogle Scholar
- Costa PT, Terracciano A, McCrae R: Gender differences in personality across cultures: Robust and surprising findings. J Pers Soc Psychol. 2001, 81: 322-331. 10.1037/0022-3522.214.171.1242.View ArticlePubMedGoogle Scholar
- McCrae RR, Terracciano A: Universal features of personality traits from the observer's perspective: Data from 50 countries. J Pers Soc Psychol. 2005, 88: 547-561. 10.1037/0022-35126.96.36.1997.View ArticlePubMedGoogle Scholar
- Widiger TA, Trull TJ: Personality and Psychopathology – An Application of the 5-Factor Model. J Pers. 1992, 60: 363-393. 10.1111/j.1467-6494.1992.tb00977.x.View ArticlePubMedGoogle Scholar
- Malouff JM, Thorsteinsson EB, Schutte NS: The relationship between the five-factor model of personality and symptoms of clinical disorders: A meta-analysis. J Psychopathol Behav. 2005, 27: 101-114. 10.1007/s10862-005-5384-y.View ArticleGoogle Scholar
- Saulsman LM, Page AC: The five-factor model and personality disorder empirical literature: A meta-analytic review. Clin Psychol Rev. 2004, 23: 1055-1085. 10.1016/j.cpr.2002.09.001.View ArticlePubMedGoogle Scholar
- Widiger TA, Costa PTJ: Personality and Personality Disorders. [Review]. J Abnorm Psychol. 1994, 103: 78-91. 10.1037/0021-843X.103.1.78.View ArticlePubMedGoogle Scholar
- Ball SA, Tennen H, Poling JC, Kranzler HR, Rounsaville BJ: Personality, temperament, and character dimensions and the DSM-IV personality disorders in substance abusers. J Abnorm Psychol. 1997, 106: 545-553. 10.1037/0021-843X.106.4.545.View ArticlePubMedGoogle Scholar
- Conway KP, Kane RJ, Ball SA, Poling JC, Rounsaville BJ: Personality, substance of choice, and polysubstance involvement among substance dependent patients. Drug Alcohol Depend. 2003, 71: 65-75. 10.1016/S0376-8716(03)00068-1.View ArticlePubMedGoogle Scholar
- Martin ED, Sher KJ: Family History of Alcoholism, Alcohol-Use Disorders and the 5-Factor Model of Personality. J Stud Alcohol. 1994, 55: 81-90.View ArticlePubMedGoogle Scholar
- Trull TJ, Sher KJ: Relationship Between the 5-Factor Model of Personality and Axis-I Disorders in A Nonclinical Sample. J Abnorm Psychol. 1994, 103: 350-360. 10.1037/0021-843X.103.2.350.View ArticlePubMedGoogle Scholar
- Piedmont RL, Ciarrocchi JW: The utility of the revised NEO personality inventory in an outpatient, drug rehabilitation context. Psychol Addict Behav. 1999, 13: 213-226. 10.1037/0893-164X.13.3.213.View ArticleGoogle Scholar
- Fisher LA, Elias JW, Ritz K: Predicting relapse to substance abuse as a function of personality dimensions. Alcohol Clin Exp Res. 1998, 22: 1041-1047. 10.1111/j.1530-0277.1998.tb03696.x.View ArticlePubMedGoogle Scholar
- Terracciano A, Costa PT: Smoking and the Five-Factor Model of personality. Addiction. 2004, 99: 472-481. 10.1111/j.1360-0443.2004.00687.x.View ArticlePubMedPubMed CentralGoogle Scholar
- Brooner RK, Schmidt CW, Herbst JH: Personality trait charcteristics of opioid abusers with and without comorbid personality disorders. Personality disorders : and the five-factor model of personality. Edited by: Costa PT, Widiger TA. 2002, Washington, D.C.: American Psychological AssociationGoogle Scholar
- Carter JA, Herbst JH, Stoller KB, King V, Kidorf MS, Costa PT, Brooner RK: Short-term stability of NEO-PI-R personality trait scores in opioid-dependent outpatients. Psychol Addict Behav. 2001, 15: 255-260. 10.1037/0893-164X.15.3.255.View ArticlePubMedGoogle Scholar
- Kornør H, Waal H, Ali RL: Abstinence-orientated buprenorphine replacement therapy for young adults in out-patient counselling. Drug Alcohol Rev. 2006, 25: 123-130. 10.1080/09595230500537209.View ArticlePubMedGoogle Scholar
- Kornør H, Waal H, Sandvik L: Time-limited buprenorphine replacement therapy for opioid dependence: 2-year follow-up outcomes in relation to programme completion and current agonist therapy status. Drug Alcohol Rev. 2007, 26: 135-141. 10.1080/09595230601146603.View ArticlePubMedGoogle Scholar
- Robins LN, Wing J, Wittchen HU, Helzer JE, Babor TF, Burke J, Farmer A, Jablenski A, Pickens R, Regier DA, et al: The Composite International Diagnostic Interview – An Epidemiologic Instrument Suitable for Use in Conjunction with Different Diagnostic Systems and in Different Cultures. Arch Gen Psychiatry. 1988, 45: 1069-1077.View ArticlePubMedGoogle Scholar
- Martinsen Ø, Nordvik H, Østbø L: Norske versjoner av NEO PI-R og NEO FFI [Norwegian versions of NEO PI-R and NEO FFI]. Tidsskrift for Norsk Psykologforening. 2005, 42: 421-423.Google Scholar
- SPSS Inc: SPSS for Windows, 11.0. 2001, Chicago, SPSS IncGoogle Scholar
- Cohen J: A Power Primer. Psychol Bull. 1992, 112: 155-159. 10.1037/0033-2909.112.1.155.View ArticlePubMedGoogle Scholar
- Booth-Kewley S, Vickers RR: Associations Between Major Domains of Personality and Health Behavior. J Pers. 1994, 62: 282-298. 10.1111/j.1467-6494.1994.tb00298.x.View ArticleGoogle Scholar
- Trobst KK, Wiggins JS, Costa PT, Herbst JH, Mccrae RR, Masters HL: Personality psychology and problem behaviors: HIV risk and the five-factor model. J Pers. 2000, 68: 1233-1252. 10.1111/1467-6494.00133.View ArticlePubMedGoogle Scholar
- Vollrath M, Knoch D, Cassano L: Personality, risky health behaviour, and perceived susceptibility to health risks. Eur J Personality. 1999, 13: 39-50. 10.1002/(SICI)1099-0984(199901/02)13:1<39::AID-PER328>3.0.CO;2-J.View ArticleGoogle Scholar
- Vollrath M, Torgersen S: Who takes health risks? A probe into eight personality types. Pers Indiv Differ. 2002, 32: 1185-1197. 10.1016/S0191-8869(01)00080-0.View ArticleGoogle Scholar
- Piedmont RL: Cracking the plaster cast: Big Five personality change during intensive outpatient counselling. J Res Pers. 2001, 35: 500-520. 10.1006/jrpe.2001.2326.View ArticleGoogle Scholar
- McCrae RR, Costa PT: Personality in Adulthood. 1990, New York: GuildfordGoogle Scholar
- Loehlin JC: Genes and environment in personality development. 1992, Newbury Park, CA: SagePublicationsGoogle Scholar
- Matthews G, Deary IJ: Personality traits. 1998, New York, NY, US: Cambridge University PressGoogle Scholar
- Lee W, Hotopf M: Personality variation and age: trait instability or measurement unreliability?. Pers Indiv Differ. 2005, 38: 883-890. 10.1016/j.paid.2004.06.014.View ArticleGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-244X/7/37/prepub
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