Validation of a System of Classifying Female Substance Abusers on ...

Psychology of Addictive Behaviors 2000, Vol. 14, No. 3, 243-256

Copyright 2000 by the Educational Publishing Foundation 0893-164X/OW5.00 DOI: 10.1037//0893-164X.14.3.243

Validation of a System of Classifying Female Substance Abusers on the Basis of Personality and Motivational Risk Factors for Substance Abuse Patricia J. Conrod

Robert O. Pihl

State University of New York at Stony Brook

McGill University

Sherry H. Stewart

Maurice Dongier

Dalhousie University

McGill University-Douglas Hospital Alcohol Research Program

This study explored the validity of classifying a community-recruited sample of substance-abusing women (N = 293) according to 4 personality risk factors for substance abuse (anxiety sensitivity, introversion-hopelessness, sensation seeking, and impulsivity). Cluster analyses reliably identified 5 subtypes of women who demonstrated differential lifetime risk for various addictive and nonaddictive disorders. An anxiety-sensitive subtype demonstrated greater lifetime risk for anxiolytic dependence, somatization disorder, and simple phobia, whereas an introverted-hopeless subtype evidenced a greater lifetime risk for opioid dependence, social phobia, and panic and depressive disorders. Sensation seeking was associated with exclusive alcohol dependence, and impulsivity was associated with higher rates of antisocial personality disorder and cocaine and alcohol dependence. Finally, a low personality risk subtype demonstrated lower lifetime rates of substance dependence and psychopathology.

A recent approach to understanding drug addiction has been to differentiate substance abusers according to their degree of vulnerability to experience specific drug-reinforcement effects, For example, Cloninger's (1987) neurobiologi-

cal learning model of alcoholism maintains that the heterogeneity of alcoholism is best captured by a typology that distinguishes alcoholics on the basis of early versus late onset of the disorder, presence of neurotic versus impulsive disorders, and sensitivity to anxiety reduction versus "perceptual reactance" reduction from alcohol. Patricia J. Conrod, Department of Psychology, D ite i(s popularity, this typology has been State Unrvers.ty of New York at Stony Brook; Robert ^^ ^ ^^ wjm reliability, to O. Pihl, Department of Psychology and Department .... ._. „ ... ,„„,. _ . , , of Psychiatry, McGill University, Montreal, Quebec, vahd"y 1996; Penmck et al199 Canada; Sherry H. Stewart, Department of Psychol°)< ™* clmlcal utjllty (Kadden, 1996). One ogy and Department of Psychiatry, Dalhousie Unipossible explanation for why this typology fails versity, Halifax, Nova Scotia, Canada; Maurice to account for the heterogeneity observed in Dongier, Department of Psychiatry, McGill Uni- alcoholic samples (e.g., Glenn & Nixon, 1996) versity-Douglas Hospital Alcohol Research Pro- is that it does not consider other potential gram, Verdun, Ouebec, Canada. sources of motivation for drug use that are unThis study was supported by the National Health reiate(j to anxiety or reactivity reduction. AlcoResearch and Development Program, Health Canada. hol and othef d of abus£ ^ j^^ to affect Correspondence concerning this art,cle should h functioning within brain motivational sysbe addressed to Patricia J. Conrod, Department of , ~.,, ... . . .J tems that are Psychology, State University of New York at differentially sensitive to various Stony Brook, Stony Brook, New York 11794stimuli classes (e.g., positive, negative, threat). 2500. Electronic mail may be sent to pconrod@ As such, addictive substances are often classims.cc.sunysb.edu. fied on the basis of the manner in which they 243

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CONROD, PIHL, STEWART, AND DONGIER

interact with these brain systems and the type of reinforcement that they produce. In addition to anxiolytic and stimulus reactivity-dampening effects, alcohol and certain other addictive substances are known to have analgesic and psychostimulant properties (DiChiara, Acquas, & Carboni, 1992; Pihl & Peterson, 1995), and individuals are known to vary in their susceptibility to such effects (Conrod, Pihl, & Vassileva, 1998). In the present study we attempted to validate a system of classifying substance-abusing individuals on the basis of their differential liability to seek out specific reinforcing effects from drugs of abuse. Consistent with Cloninger's (1987) original hypothesis, specific personality risk factors for substance abuse are assumed to reflect differences in the functioning of brain motivational systems and differential susceptibility to seek out specific drug-reinforcement effects. However, the current classification system will involve an expansion of Cloninger's typology to focus on four personality risk factors and corresponding motivational determinants of drug use and abuse. They are anxiety sensitivity, introversion-hopelessness, sensation seeking, and impulsivity. In the sections that follow we briefly review converging literatures suggesting that these factors are linked to specific patterns of addictive and nonaddictive psychopathology by means of their relationship to brain motivational systems that are specifically affected by drugs of abuse. Anxiety sensitivity refers to a cognitive or personality style that involves an expectation or fear that anxiety and physical arousal will lead to physical illness, social embarrassment, loss of mental control, or some combination of these (Reiss, Peterson, Gursky, & McNally, 1986). As such, it is associated with a five-fold increased risk for the longer term development of panic-related anxiety disorders (Mailer & Reiss, 1992) and corresponds with self-reported rates of alcohol (Stewart, Peterson, & Pihl, 1995) and anxiolytic prescription drug use (Bruce, Speigel, Gregg, & Nuzzarello, 1992). Furthermore, this personality style is associated with sensitivity to the anxiety-reducing effects of alcohol and the tendency to self-report motives for alcohol use that reflect the desire to self-medicate negative emotions (Conrod, Pihl, & Vassileva, 1998; Stewart & Pihl, 1994). It has been sug-

gested that anxiety sensitivity is a personality risk factor for dependence on drugs that posses anxiolytic properties (such as alcohol and benzodiazepines) that is due to a need to escape feared symptoms of anxiety (Stewart, 1996). Depression may also be considered a risk factor for alcoholism in that it is predictive of later alcohol consumption and the development of alcohol problems, particularly for women (Hartka et al., 1991; Helzer & Pryzbeck, 1988). In terms of personality factors that are common to both depression and alcoholism, primarily depressed alcoholics have been shown to differ from nondepressed and secondarily depressed alcoholics on measures of personality that reflect trait anxiety and introversion (Epstein, Ginsburg, Hesselbrock, & Schwartz, 1994; Martin & Sher, 1994). Introversion has been described as reflecting a sensitivity to punishmentinduced extinction of social and goal-oriented behavior (e.g., Depue & Collins, 1999). Pihl and Peterson (1995) suggested that individuals with interpersonal sensitivity, punishment sensitivity, or both appreciate the analgesic properties of alcohol (at certain doses) and certain other drugs of abuse (e.g., codeine) because analgesics suppress the inhibitory effects of punishment on previously rewarded behavior (Gray, 1982). We similarly hypothesized that introverted, depression-prone substance abusers are particularly attracted to drugs of abuse that possess analgesic properties (e.g., opioids and alcohol). Extraversion and novelty/sensation seeking are two additional personality characteristics that have been associated with elevated drug use; however, they are more associated with a tendency to drink to experience the euphoric and intoxicating effects of alcohol (Conrod, Peterson, & Pihl, 1997; Ohannessian & Hesselbrock, 1994) rather than the negatively reinforcing effects. The psychomotor stimulant theory of addiction suggests that the addictive properties of drugs of abuse are partially determined by their ability to increase dopamine in a brain system that causes intrinsically rewarding states when stimulated (Fibiger & Phillips, 1988; Wise & Bozarth, 1987). Extraversion and sensation seeking have been linked to specific dopamine-related biochemical mechanisms that are related to the functioning of this incentive reward system (Depue & Collins, 1999). There-

SUBTYPES OF SUBSTANCE ABUSERS fore, among a number of possible determinants of alcohol use (Sher, 1993), one important factor may involve a specific sensitivity to incentive motivation and the psychostimulant properties of alcohol (Conrod et al., 1998). Accordingly, we proposed that a subtype of substance abuser, defined primarily on the basis of sensitivity to incentive motivation (sensation seeking), will be associated with a propensity toward alcohol abuse in the absence of other forms of psychopathology and personality risk factors. Finally, impulsive-disinhibited personality has been linked to elevated risk for early-onset alcohol and drug problems (e.g., Pulkkinen & Pitkanen, 1994). This personality profile has been operationally described as an insufficient ability to anticipate future reinforcement and delay behavioral responses accordingly (Pihl & Peterson, 1995; Spoont, 1992). In contrast to the traditional self-medication hypothesis, or the psychomotor stimulant theory, a self-regulation deficit might be more appropriate for explaining the motivational link between impulsivity and drug abuse. That is, heavy and problematic drug use may be consequential to a lack of inhibition in the face of negative consequences associated with the use of certain substances if such substances are immediately reinforcing. Accordingly, impulsive substance abusers should discriminate from a sensation-seeking subtype and other subtypes on the basis of their propensity toward antisocial behavior and patterns of drug use that involve use of illegal substances and severe negative consequences of such use. We proposed that subtypes of substance abusers, identified on the basis of specific personality profiles (proposed to reflect specific motivational liabilities for drug abuse), will present with specific patterns of comorbid psychopathology and substance dependence. We chose to validate this motivational model of substance abuse within a population polysubstance abusing/dependent women because of the relative paucity of research on substance abuse in women and to allow for the identification of factors that are potentially gender specific. This investigation was conducted within a community-recruited sample, rather than a treatment sample, to address the concerns about the representativeness of treatment samples

245

with respect to polysubstance abuse and comorbid psychopathology (Nathan, 1987).

Method Participants Three hundred non-treatment-seeking female substance abusers were recruited between August 1995 and September 1996 through advertisements featured in English and French entertainment and community newspapers freely circulated in the greater Montreal area. In total, 790 women responded to the advertisements and were screened with a 30-min telephone interview. The inclusion criteria for the study were as follows: between 30 and 50 years of age (i.e., the age range at which distributions for the abuse of alcohol, prescription drugs, and other psychoactive substances overlap for women) and dependence on or abuse of alcohol, prescription drugs, or both (as a means of oversampling for prescription drug dependence/abuse). Screening for alcohol and substance abuse involved use of the brief version of the Michigan Alcoholism Screening Test (Brief MAST; Pokorny, Miller, & Kaplan, 1972) and the Drag Abuse Screening Test (DAST; Skinner, 1982). Participants who scored above 10 on the Brief MAST (Fleming & Barry, 1989)' and/or 12 on the DAST were considered to be abusing a substance (Skinner, 1982). Alcohol and drug dependencies were diagnosed if respondents met three or more of the seven Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV]; American Psychiatric Association, 1994) criteria indicating substance dependence within the previous 12 months. To increase the reliability of the self-report measures used in the present investigation, we excluded participants who had been diagnosed with or medicated for a psychotic or bipolar disorder within the previous 2 years and those who currently had a serious medical condition for which alcohol and drug consumption were contraindicated (e.g., pregnancy). Respondents were not excluded if they concurrently abused or were dependent on other psychoactive substances in addition to alcohol and/or prescription drugs. The sample prevalences for current dependence on various psychoactive substances are as follows: 84.2% for alcohol, 26.7% for anxiolytics, 6.2% for opioids, 19.9% for

1 Although Pokorny's original study suggests a cutoff score of 6 for the Brief MAST, more recent studies suggest that the specificity and sensitivity of abbreviated forms of the MAST using weighted items are significantly improved when the cutoff score for a diagnosis of alcoholism is raised from 5 to 10 (Fleming & Barry, 1989).

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CONROD, PIHL, STEWART, AND DONGIER

cocaine, and 9.9% for cannabis. Sixty percent of the sample met criteria for dependence on only one substance, 28.2% for two substances, and 11.1% for three or more substances. The polysubstance-abusing nature of the sample permitted us to explore the validity of the motivational model of substance abuse as it pertains to female substance abusers who are using and are dependent on a variety of psychoactive substances. Procedure Eligible respondents were scheduled to participate in a full day (5 hr) of psychological testing during which time they completed a number of psychological tests and questionnaires on a computer. All participants were provided with $35 Canadian as compensation for their time.

abuse using the telephone-administered Brief MAST (Pokorny et al., 1972) and the DAST (Skinner, 1982), (b) current alcohol and drug dependence according to DSM-IV criteria (American Psychiatric Association, 1994), (c) average quantity-frequency estimates and special-occasion quantity-frequency estimates of alcohol and substance use (obtained during the telephone interview and during a structured interview involving the Timeline Follow Back method developed by Sobell & Sobell, 1992), and (d) lifetime alcohol and drug abuse and dependence using the Alcohol and Drug Dependence modules of the C-DIS.

Results

Demographic Assessment of Motivational

Profiles

Table 1 lists the personality and symptom inventories selected to measure variation on four dimensions of psychological functioning that we propose differentially motivate individuals to seek reinforcement from drugs of abuse.2 Because these measures are widely used in current research on psychopathology, and evidence for their reliability and validity has been previously documented, they are not reviewed here.

Characteristics

of the Sample The recruitment procedure resulted in the selection of 300 women for participation in the study. In total, 293 women (97.7%) completed the full assessment battery; 70% were French speaking. Table 2 details the demographic characteristics of the sample.

Derivation of Personality Risk Profiles Assessment of Psychopathology We used the Computerized Diagnostic Interview Schedule (C-DIS; C-DIS Management Group, 1991) to assess lifetime diagnoses of psychiatric disorders according to criteria specified by the DSM—H1—R (American Psychiatric Association, 1987). The C-DIS provides a standardized format for questioning individuals about their symptoms while abiding by the DSM-1II-R decision rules and ensures adequate coverage of all relevant criteria. The C-DIS has been shown to have adequate test-retest reliability (Blouin, Perez, & Blouin, 1988) and a sensitivity that is equivalent to that of a computer-prompted version of the DIS (Erdman et al., 1992). Participants were assessed for all mood, anxiety, and psychoactive substance-use disorders as well as for antisocial personality disorder, somatization disorder, somatoform pain disorder, anorexia nervosa, bulimia nervosa, and pathological gambling. Measures of Alcohol and Substance Use, Dependence, and Abuse Four dimensions of drug- and alcohol-related behavior were assessed: (a) current alcohol and drug

We performed a factor analysis on the entire battery of personality and symptom inventories (excluding C-DIS and substance use information). We used an eigenvalue > 1.0 criterion for factor extraction; four factors emerged representing Anxiety Sensitivity, Sensation Seeking, Impulsivity, and Introversion-Hopelessness, which together accounted for 69.3% of the variance in the data. Table 1 presents factor loadings after varimax rotation. We then randomly split the sample into two subsamples and performed similar factor analyses. Pairwise correlations between factor loadings for each factor across the two subsamples

2 To accommodate the bilingual nature of this Quebec sample, all tests and measures were available in French and English. French translations were performed by employees of our research team who were experienced in English-to-French translation. As a verification of each translation, they were then backtranslated by a separate employee, and modifications to the original translation were made accordingly.

SUBTYPES OF SUBSTANCE ABUSERS

247

Table 1 Results of Factor and Cluster Analyses: Factor Loadings of Personality and Symptom Inventories Onto Four Factors and Factor Scores of Five Clusters of Substance Abusers Following Cluster Analysis Anxiety Sensation Impulsivity/ Introversion/ Sensitivity Seeking Hostility Hopelessness

Personality or symptom inventory Neuroticism (NEO-FFI-N; Costa & McCrae, 1992) Trait anxiety (STAI-T; Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, 1983) Anxiety sensitivity (ASI; Peterson & Reiss, 1992) Anxious cognitions (CCL-Anx; Beck, Brown, Eidelson, Steer, & Riskind, 1987) PTSD symptoms (PSS-SR; Foa et al., 1993) Depressive cognitions (CCL-Dep; Beck et al., 1987) Extroversion (NEO-FFI-E; Costa & McCrae, 1992) Depressive symptoms (BDI; Beck, Ward, Mendelson, Mock, & Erbaugh, 1961) Low self-esteem (SES; Rosenberg, 1965) Hopelessness (BHS; Beck, Weissman, Lester, & Trexler, 1974) Sensation seeking (SSS; Zuckerman, 1979) Venturesomeness (Eysenck & Eysenck, 1978) Openness (NEO-FFI-O; Costa & McCrae, 1992) Impulsiveness (Eysenck & Eysenck, 1978) Agreeableness (NEO-FFI-A; Costa & McCrae, 1992) Conscientiousness (NEO-FH-C; Costa & McCrae, 1992)

.62

.52

.64 .79

.58

.75 .75 .58

.67

.52 .75 .69 .88 .81 .68

-.46 .75 -.73 -.58

Clusters of female substance abusers Anxiety sensitive (n = 53) M SD Introverted/hopeless (n = 53) M SD Sensation seeking (n = 72) M SD Impulsive (n = 73) M SD Low personality risk (n = 42) M SD

.63 -.76

Factor scores 1.34 0.60

-0.25 0.84

0.67 0.72

-0.20 0.84

-0.00 0.84

-0.12 0.90

-0.75 0.66

1.24 0.75

-0.23 0.75

0.84 0.60

-0.65 0.58

-0.58 0.65

-0.68 0.60

0.15 0.85

1.00 0.65

0.22 0.85

-0.10 0.85

-1.22 0.65

-0.51 0.73

-0.69 0.56

Note. NEO-FFI-N = NEO Five-Factor Inventory—Neuroticism scale; STAI-T = State-Trait Anxiety Inventory, Trait scale; ASI = Anxiety Sensitive Index; CCL-Anx = Cognition Checklist—Anxiety scale; PTSD = posttraumatic stress disorder; PSS-SR = Posttraumatic Stress Symptom Scale—Self Report; CCL-Dep = CCL—Depression scale; NEO-FFI-E = NEO-FFI—Extroversion scale; BDI = Beck Depression Inventory; SES = Self-Esteem Scale; BHS = Beck Hopelessness Scale; SSS = Sensation-Seeking Scale Form V; NEO-FFI-O = NEO-FFI—Openness scale; NEO-FFI-A = NEO-FFI—Agreeableness scale; NEO-FFI-C = NEO-FFI—Conscientiousness scale. were very high (r = .94-98), thus demonstrating the reliability of the factor-analytic findings.3 We then performed cluster analyses to gain a perspective on the distribution of such fac-

the previous analysis. The percentage change in agglomeration coefficients (sum of the

tors in the current sample. We obtained initial clusters using Ward's squared Euclidean distance method using factor scores yielded from

3 Confirmatory factor analyses were performed to compare the fit of this four-factor model relative to 2 three-factor models (in which anxiety- and

CONROD, PIHL, STEWART, AND DONGIER

248

Table 2 Demographic Characteristics of Five Subtypes of Female Substance Abusers: Subtype and Total Sample Percentages or Means Variable Age M SD Marital status (%) Never married Married, living with spouse Common-law married Married but separated Widowed Divorced Living situation (%) Living alone Living with spouse Living with roommate Living with children only Living with parents No. of children M SD Education (years) M SD Level of education (%) High school incomplete High school diploma College degree 1-4 years university Postgraduate degree Current employment (%) Full time Part time Unemployed Homemaker Full-time student Personal income M SD

Total

Anxiety sensitive

Introverted/ hopeless

Sensation seeking

Impulsive

Low personality risk

38.7 5.90

38.3 5.9

39.9 6.3

38.6 5.8

37.8 5.4

39.5 6.4

51.9 7.6 7.9 6.5 1.7 24.4

46.2 13.5 5.8 9.6 5.8 19.2

55.8 11.5 5.8 5.8 0 21.2

56.9 1.4 11.1 8.3 0 22.2

58.9 5.5 6.8 4.1 1.4 23.3

33.3 9.5 9.5 4.8 2.4 40.5

38.3 25.9 10.0 24.1 1.7

40.4 32.7 5.8 21.2 0

44.2 23.1 9.6 17.3 5.8

37.5 22.2 12.5 26.4 1.4

30.1 27.4 12.3 28.8 1.4

43.9 24.4 7.3 24.4 0

1.0 1.0

1.1 1.1

0.9 1.2

1.0 1.0

1.0 0.9

1.1 1.2

12.9 3.8

11.8 3.7

14.4 3.9

13.9 3.7

12.0 3.3

12.0 3.5

15.9 37.4 12.8 29.1 4.8

23.1 40.4 11.5 23.1 1.9

11.8 29.4 15.7 35.3 7.8

12.5 27.8 8.3 44.4 6.9

18.1 45.8 11.1 20.8 4.2

14.3 45.2 21.4 16.7 2.4

17.5 14.4 37.7 27.1 3.4

24.5 7.5 22.6 41.5 3.8

17.3 15.4 46.2 19.2 1.9

23.6 16.7 33.3 23.6 2.8

5.5 17.8 45.2 26.0 5.5

19.0 11.9 40.5 26.2 2.4

13,479 13,375

12,956 10,967

14,354 10,465

11,092 13,322

13,150 9,799

12,957 11,747

squared distances between clusters) to next level for 2 to 9 clusters, respectively, were

depression-relevant items were forced onto one factor or anxiety and depression factors were held separate and impulsivity and sensation-seeking items were forced on one factor) and a two-factor model (in which anxiety- and depression-relevant items were forced onto one factor and impulsivity and sensation seeking were forced onto another). Results of these analyses are: four-factor model: x*(92, N = 243) = 323.5, three-factor model: ^(88, N = 243) = 576.4, and ^(87, N = 243) = 456.8, two-factor, ^(86, N = 243) = 374.8, and indicate superiority of the fourfactor model relative to the alternative models.

15.9, 15.2, 13.1, 10.0, 10.0, 7.3, 6.6, and 6.7. The scree plot method for determining the number of clusters in a data set (as suggested by Hair, Anderson, Tathames, & Black, 1995) indicated a five-cluster solution (i.e., the point at which the slope for change in agglomeration coefficients became 0). We then performed a K-means clustering analysis, constrained to a five-cluster solution, on factor scores using cluster centroids from the hierarchical cluster analysis. Table 1 also presents mean factor scores on each motivational dimension for the five clusters yielded from this analysis. We then repeated this procedure on the two split-half samples to assess the reli-

249

SUBTYPES OF SUBSTANCE ABUSERS ability of the findings. The scree plot method and Mojena's (1977) rules for determining the number of clusters in a data set suggested five-cluster solutions for both samples. Chisquare analysis indicated a highly significant rate of agreement (86%) between cluster assignments based on the full and split-half sample solutions, x*(\6, N = 293) = 786.4, p < .00001. Analysis of cluster group effects on the demographic variables (Table 2) indicated cluster effects on total number of years of education completed, F(4, 288) = 6.04, p < .01; level of education, *2(16, N = 293) = 26.19, p < .06; and current employment status, x2(16, N = 293) = 26.34, p < .08. Post hoc chi-square analyses exploring these effects indicated that (a) introverted-hopeless and sensation-seeking women were more likely to achieve postsecondary levels of education (p < .01), (b) impulsive women were underrepresented in the full-time employment category (p < .05), and (c) anxiety-sensitive women more often indicated homemaking as their full-time employment (p < .05).

Validation of Clusters Differential vulnerability to DSM-III-R lifetime psychiatric disorders. Lifetime prevalences for DSM-Hl-R nonaddictive disorders for this sample and self-report mean age of onset of first symptom for each disorder appear in Table 3 . We assessed group differences in risk for each lifetime diagnosis using chi-square analyses on rates of diagnosis in each group relative to the rate of diagnosis across the entire sample. Results indicated significant cluster main effects for lifetime diagnoses of major depressive episode, j^(4, N = 284) = 10.43, p < .01; recurrent major depression, ^(4, N = 284) = 4.48, p < .05; panic disorder, )f(4, N = 284) = 5.92, p < .05; social phobia, ^(4, N = 284) = 9.66, p < .01; simple phobia, ^(4, N = 284) = 5.30, p < .05; somatization, /(4, N = 284) = 19.08, p < .001; and antisocial personality disorder, xi(4, N = 284) = 6.57, p
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251

SUBTYPES OF SUBSTANCE ABUSERS

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