A comparison of impulsivity,depressive symptoms,lifetime stress and sensation seeking in healthy controls versus participants with cocaine or methamphetamine use disorders

Abstract

Previous research has focused on developing theories of addiction that may explain behavior in cocaine- and methamphetamine-dependent individuals. The primary goal of this report was to compare and contrast the prevalence of self-reported measures of impulsivity, depression, lifetime stress and sensation-seeking in healthy controls versus individuals with cocaine or methamphetamine use disorders. Twenty-nine individuals with cocaine use disorders and 31 individuals with methamphetamine use disorders were matched with 31 healthy control participants on several demographic variables. All participants were administered behavioral questionnaires including the Barrett Impulsiveness Scale (assessing impulsivity), Beck Depression Inventory II (assessing depression), Life Stressor Checklist–Revised (assessing lifetime stress) and the Impulsive Sensation Seeking Scale (assessing sensation-seeking). When compared to healthy controls, individuals with cocaine and methamphetamine use disorders had significantly higher levels of impulsivity and sensation-seeking. In addition, when compared to healthy controls, individuals with cocaine use disorders had significantly higher Beck Depression Inventory II scores, while individuals with methamphetamine use disorders had significantly higher Life Stressor Checklist–Revised scores. The results revealed that there were significantly higher levels of impulsivity, depression and sensation-seeking in cocaine users and significantly higher impulsivity, lifetime stress and sensation-seeking in methamphetamine users when compared to healthy controls.

Keywords

Stress impulsivity depression sensation seeking cocaine methamphetamine

Introduction

The United States Department of Health and Human Services estimated that there were 1.6 million current cocaine users and 440,000 current methamphetamine users in 2012 (Substance Abuse and Mental Health Services Administration (SAMHSA), 2012). Previous research has focused on developing theories of addiction that may explain behavior in cocaine- and methamphetamine-dependent individuals. For example, different theories of addiction have emphasized inhibitory control dysfunction (impulsivity), negative reinforcement (pain avoidance), positive reinforcement (pleasure seeking), incentive salience (craving), and stimulus response habits (Newton et al., 2009; West, 2001).

In a sample of 73 methamphetamine-dependent individuals, Newton et al. (2009) reported that 56% of participants self-reported that they used methamphetamine due to pleasure seeking and 30% of respondents used due to pain avoidance, while 27% of participants used drugs due to impulsivity. In addition, 41% reported that they did not use methamphetamine due to habit and 30% reported that they did not use due to craving. Moreover, correlations between ratings on a summary question for each of the aforementioned categories and Beck Depression Inventory II (BDI-II) scores revealed that negative reinforcement, incentive salience, stimulus–response learning, and impaired inhibitory control were all positively correlated with BDI-II scores (Newton et al., 2009). Similarly, Haile et al. (2013), utilized the same assessment (theories of addiction questionnaire) in cocaine-dependent individuals and found that 63% of participants affirmed that they used due to pleasure seeking and responses from most categories (with the exception of pleasure seeking) were also positively correlated with BDI-II scores.

In the current study, we sought to investigate the prevalence of symptoms across four dimensions (depression, stress, impulsivity and sensation seeking) in participants with stimulant use disorders and healthy controls. Specifically, we compared depressive symptomatology, as measured by the BDI-II, in healthy controls and non-treatment seeking individuals with stimulant use disorders to evaluate the disparity between groups. Because there are high rates of depressive symptoms among individuals with stimulant use disorders, and symptoms of depression may enhance responses to cocaine and thereby increase cocaine use (Sofuoglu et al., 2001), understanding the prevalence of these symptoms may help to personalize medication and behavioral treatments to target these specific symptoms.

We then examined the prevalence of stressful life events in healthy controls as compared to individuals with stimulant use disorders. Since chronic stress may have an aversive impact on daily living, individuals may have a tendency to cope using drugs. This hypothesis is supported by previous research demonstrating that craving associated with psychological stress may be related to cocaine use (Sinha et al., 2000). In addition, previous research conducted by our laboratory found that cocaine-dependent individuals reported experiencing approximately eight stressful life events (out of 30 possible) as measured by the Life Stressor Checklist (Mahoney et al., 2013b) while methamphetamine-dependent individuals reported experiencing approximately nine stressful life events (Mahoney et al., 2013a).

Next, we investigated the prevalence of impulsivity within healthy controls as compared to individuals with stimulant use disorders as measured by the Barrett Impulsiveness Scale (BIS). One potential contributing factor to continued drug use is a lack of impulse control over drug intake and a compulsive pattern of drug-seeking and drug-taking behaviors (West, 2001). Impulsivity is common in drug dependent individuals (Reynolds, 2006) and is commonly associated with cocaine dependence (Bornovalova et al., 2005a, 2005b; Fillmore and Rush, 2002; Li et al., 2006; Moeller et al., 2001, 2002; Patkar et al., 2003; Verdejo-Garcia et al., 2007a, 2007b).

In addition to impulsivity, we assessed the prevalence of sensation seeking, which is defined as ‘the need for varied, novel, and complex sensations and experiences and the willingness to take physical and social risks for the sake of such experience’ (Zuckerman and Neeb, 1979). Sensation seeking has been shown to predispose an individual to drug use (Teichman et al., 1989) and increased sensation seeking has been noted in cocaine-dependent individuals (Ersche et al., 2010; Patkar et al., 2002, 2003).

The Substance Abuse Research Program at the Baylor College of Medicine (BCM) is continuing efforts to evaluate medications for stimulant use disorders. More importantly, we want to determine how various behavioral symptoms or phenotypes compare to healthy controls since it may guide the medication development process. The primary goal of this report was to compare and contrast the prevalence of self-reported measures of impulsivity, depression, lifetime stress and sensation seeking in healthy controls versus individuals with cocaine or methamphetamine use disorders. We hypothesized that impulsivity, depressive symptoms, life stress and sensation seeking would be significantly higher in individuals with cocaine or methamphetamine use disorders when compared to healthy controls.

Experimental procedures

Participants

The current study includes data obtained between February, 2010 and March, 2013 at BCM. Participants were recruited from the Houston metropolitan area through newspaper and radio advertisements. All participants completed an initial telephone screen in order to assess basic eligibility. Candidates who passed this telephone screening were then invited to complete an in-person assessment at the Research Commons of the Michael E. DeBakey VA Medical Center. During the in-person interview, candidates received an explanation of the study purpose and requirements and were allowed to review, inquire about and sign the informed consent form. All volunteers provided consent after being fully informed about potential risks of study participation. Participants were compensated with a $40 gift card for completing the in-person screen.

For the current report, participants met the following inclusion criteria for this investigation: (a) met DSM-IV criteria for cocaine or methamphetamine dependence, but not both (with the exception of the healthy control subjects who were required to meet no criteria for any DSM-IV diagnoses other than nicotine dependence); (b) were 18–65 years of age; (c) were not seeking treatment for cocaine or methamphetamine use. Participants were excluded if they met any of the following exclusion criteria: (a) had a substance use disorder other than cocaine, methamphetamine, or nicotine; (b) met current or past DSM-IV criteria for any neuropsychiatric disorder including major depressive disorder, mania or post-traumatic stress disorder (PTSD). In order to be included in the analysis, control participants were required to provide a urine sample that was negative for the following substances: cocaine; methamphetamine; amphetamine; marijuana; opiates. Cocaine and methamphetamine users were required to be negative for all substances with the exception of their stimulant of choice and marijuana. In addition, no participants were included if they were actively taking any prescription medications.

Drug use

Drug use was assessed with a 14-item, self-report questionnaire with frequency assessed in terms of date of last use, days used in the past 30, years of use, grams used per day and route of administration. Substance use frequency was assessed for alcohol, cocaine, methamphetamine, opiates, marijuana and nicotine. Recent drug use was assessed via qualitative urine toxicology (testing for cocaine, amphetamine, methamphetamine, marijuana and opiates).

Barratt Impulsiveness Scale (BIS)

The BIS (Patton et al., 1995) was selected to assess levels of general impulsivity, as it has consistently been used to measure this construct in cocaine-dependent samples (Kjome et al., 2010; Liu et al., 2011; Schmitz et al., 2009). The BIS measures impulsive personality traits through a 30-item self-report questionnaire. The BIS total score is commonly utilized in analysis of this trait. Each item is rated on a 4-point scale ranging from 1 (never) to 4 (always) with a range from 30–120. While there have not yet been any established cut-off scores reported for the BIS (e.g. to deem an individual as being ‘impulsive’ versus ‘non-impulsive’), several groups suggested using the 75th percentile as a cut-off for determining high versus low impulsivity (Baca-Garcia, 2004; Maloney, 2009).

Beck Depression Inventory II (BDI-II)

The BDI-II (Beck et al. 1996) was selected to assess current symptoms of depression. Specifically, the BDI-II is a 21-question, self-report inventory that evaluates the presence of depressive symptoms on a scale of 0 (least) to 3 (highest), with a range is 0–63 where the standard cut-off scores are as follows: 0–9 indicates minimal depression; 10–18 indicates mild depression; 19–29 indicates moderate depression; 30–63 indicates severe depression.

Life Stressor Checklist–Revised (LSC-R)

The LSC-R (Wolfe and Kimerling, 1997) measures life stress in 30 areas that could elicit PTSD responses (e.g. being mugged, the death of a loved one, a sexual assault). The LSC–R assesses for whether each stressful event occurred, at what ages the events occurred, how many times each event occurred, how dangerous the event was and whether the individual had an intense emotional reaction to the event(s). The total LSC–R score is obtained by adding up the total number of experiences endorsed (thus, the range is 0–30 with 30 indicating endorsement of all experiences). It should be noted that some of the items listed in the measure are not necessarily traumatic in nature, but would likely be stress inducing. Unfortunately, there have not yet been any established cut-off scores reported on the LSC–R delineating high lifetime stress from low lifetime stress.

Impulsive Sensation Seeking Scale (ImpSSS)

Scores on the ImpSSS were computed by summing the responses to the 19-item ImpSSS adapted from the Zuckerman–Kuhlman Personality Questionnaire (Zuckerman and Kuhlman, 2000). Participants were asked whether statements such as ‘I don’t spend much time on the details of planning ahead’ and ‘I like doing things just for the thrill of it’ were either true (coded 1) or false (coded 0) about themselves. Scores ranged from 0 to 19, with higher numbers indicating higher impulsivity. There have not yet been any established cut-off scores reported on the ImpSSS.

Screening interview

Screening interviews were conducted at BCM by trained bachelor’s and master’s level research coordinators. After signing the informed consent, the research coordinator collected substance use and mood symptom data through the administration of a series of questionnaires, including the Demographic/Drug Use Information form, the BIS, BDI-II, LSC–R, ImpSSS and the Mini International Neuropsychiatric Interview to assess DSM-IV diagnostic criteria. The screening interview concluded with a urinalysis drug screen.

Exploratory analyses

To minimize the possibility that demographic factors and comorbid nicotine and alcohol use may confound the analyses, individuals with cocaine or methamphetamine use disorders were matched with healthy controls on the following variables: age; gender; years of cigarette and alcohol use. While we were able to match individuals with cocaine use disorders with control subjects on race, we were unable to match individuals with methamphetamine use disorders to controls due to recruitment limitations. Similarly, we were unable to match cocaine users with controls on years of education and unable to match methamphetamine users with controls on education, race, and number of cigarettes used per day. Since we were unable to match participants on these variables, we utilized multivariable models to adjust for these variables, which were significantly different between groups. Comparisons between healthy controls and individuals with cocaine or methamphetamine use disorders were determined using one-way analysis of variance. Pearson’s product moment correlations were then used to evaluate the association between continuous demographic (i.e. age and education) and drug use variables (i.e. years of cocaine use, recent stimulant use in the past 30 days and daily stimulant use in grams) and scores on the BIS, BDI-II, LSC–R and ImpSSS. Since the correlations demonstrated low r scores and were non–significant, we did not co-vary for any demographic or drug use variables in the analyses. Similarly, Pearson’s product moment correlations were then used to evaluate the association between the four assessments specified above. Significance was set at p<0.05. All analyses were performed using Statview (version 5.0).

Results

Healthy controls versus age matched individuals with cocaine or methamphetamine use disorders

Demographic and drug use information for healthy controls and age matched individuals with cocaine or methamphetamine use disorders is provided in Table 1. The healthy control group included predominantly Caucasian (45%) and African American (45%), males (55%), who were ~36 years of age and reported ~13 years of education. Individuals with cocaine use disorders were African American (52%) and Caucasian (48%), males (69%) who were ~37 years of age and reported ~11 years of education. On average, participants reported using cocaine for ~13 years, ~16 days out of the past month and were currently using ~2 g/day. Individuals with methamphetamine use disorders were predominantly Caucasian (71%) males (71%) who were ~35 years of age and reported ~12 years of education. On average, participants reported using methamphetamine for ~13 years, ~19 days out of the past month and were currently using ~1 g/day. In addition, a majority of participants in all groups reported smoking cigarettes and drinking alcohol.

Table 1.

Demographic/drug use characteristics (healthy controls versus age matched participants with cocaine or methamphetamine use disorders).

	Controls (n=31)	Cocaine (n=29)		Meth (n=31)
Gender (N)			p ^a		p ^a
Male	17 (55%)	20 (69%)	0.20	22 (71%)	0.15
Female	14 (45%)	9 (31%)		9 (29%)
Race/Ethnicity (N)
African American	14 (45%)	15 (52%)	0.55	1 (3%)	<0.01^b
Caucasian	14 (45%)	14 (48%)		22 (71%)
Age (years)	36.0±2.2	36.8±1.6	0.77	35.4±1.6	0.80
Education (years)	13.5±0.4	11.0±0.5^b	<0.01	12.3±0.4^b	0.03
Stimulant use
Years of use	–	13.1±1.7	–	12.9±1.5	–
Days used in the last 30	–	16.6±1.4	–	19.1±1.7	–
g/day	–	2.1±0.4	–	1.1±0.1	–
Nicotine use	n=20	n=23		n=24
Years of use	19.1±2.5	16.5±1.8	0.40	18.4±2.2	0.84
Cigarettes/day	18.9±2.4	13.5±2.9	0.17	12.0±1.5^b	0.02
Alcohol use	n=17	n=17		n=16
Years of use	13.9±2.8	14.7±2.6	0.82	18.4±2.0	0.20
Days used in the last 30	7.5±2.3	10.7±2.2	0.32	6.9±2.0	0.87

Values represent mean±SEM.

p value reflects difference when compared to healthy controls.

Represents p<0.05 when compared to healthy controls.

There were no differences between the healthy control and cocaine groups on most demographic and drug use characteristics including age, years of cigarette use, years of alcohol use and days of recent alcohol use in the past 30. However, control subjects reported having significantly higher education than individuals with cocaine use disorders (p<0.0001).

On the subjective assessments administered, healthy controls and individuals with cocaine use disorders were statistically similar on the LSC–R (F_1,58 =1.408; p=0.241), while individuals with cocaine use disorders had significantly higher BIS (F_1,58 =10.308; p = 0.002), BDI–II (F_1,58 =5.307; p=0.028) and ImpSSS (F_1,58 =5.258; p=0.026) scores (Figure 1). After adjusting for education (which was significantly different between cocaine users and controls), all significant differences between groups as noted above remained significant with the exception of BDI score (p =0.163).

There were no differences between the healthy controls and methamphetamine groups on most demographic and drug use characteristics including age, years of cigarette use, years of alcohol use, and days of recent alcohol use in the past 30. However, control subjects reported having significantly higher education than individuals with methamphetamine use disorders (p=0.033) and reported smoking significantly more cigarettes per day (p=0.017).

On the subjective assessments administered, individuals with methamphetamine use disorders had significantly higher scores on the BIS (F_1,60 =15.068; p=0.0003), LSC–R (F_1,56 =6.934; p=0.011), and ImpSSS (F_1,60 =9.678; p=0.003)(Figure 1). After adjusting for education, race and cigarettes per day (which were significantly different between methamphetamine users and controls), all significant differences between groups as noted above remained significant.

Pearson’s product moment correlations revealed that demographic and drug use variables were not strongly correlated with performance on any of the subjective measures with the exception of recent and daily cocaine use and performance on the BIS (Table 2). Pearson’s product moment correlations in cocaine users revealed that BIS scores were significantly and positively correlated with BDI-II scores (p=0.026) while, in methamphetamine users, BIS scores were significantly and positively correlated with BDI-II (p=0.002) and ImpSSS (p<0.001) scores. In control participants, Pearson’s product moment correlations revealed that BIS scores were significantly and positively correlated with BDI-II (p= 0.006), LSC–R (p = 0.038) and ImpSSS (p<0.001) scores while BDI scores were significantly and positively correlated with LSC–R (p=0.041) and ImpSSS (p=0.008) scores (Table 3).

Table 2.

Correlations between demographic and drug use variables and performance on the BIS, LSC–R, BDI–II and ImpSSS.

	Control				Cocaine				Methamphetamine
	BIS	BDI	LSC	ImpSSS	BIS	BDI	LSC	ImpSSS	BIS	BDI	LSC	ImpSSS
Age	−.062	−.113	.221	−.077	.197	−.158	.119	.237	−.334	.141	−.269	−.094
Education	−.168	.218	−.111	−.006	−.112	−.103	.204	.108	.099	−.193	−.149	.238
Stim Years	–	–	–	–	−.194	−.234	−.141	−.081	−.138	.120	−.067	.129
Stim Recent	–	–	–	–	.476^a	.053	.065	.268	.139	−.066	−.048	−.077
Stim Daily	–	–	–	–	.409^a	.195	−.074	.039	.080	−.010	−.007	−.111

P values reflect significance of correlation.

p< 0.05.

Table 3.

Correlations between the BIS, LSC–R, BDI-II and ImpSSS.

	Control			Cocaine			Methamphetamine
	BDI	LSC	ImpSSS	BDI	LSC	ImpSSS	BDI	LSC	ImpSSS
BIS	.475^a	.399^a	.788^a	.409^a	.014	.335	.530^a	.209	.749^a
BDI	–	.394^a	.465^a	–	.173	.225	–	−.287	.338
LSC	–	–	.264	–	–	–.156	–	–	.068

P values reflect significance of correlation.

p< 0.05.

Discussion

The primary goal of this report was to compare and contrast prevalence of self-reported measures of impulsivity, depression, lifetime stress and sensation seeking in healthy controls versus individuals with cocaine or methamphetamine use disorders. The results confirmed the primary hypothesis revealing significantly higher BIS, BDI-II and ImpSSS scores in individuals with cocaine use disorders and significantly higher BIS, LSC–R and ImpSSS scores in individuals with methamphetamine use disorders when compared to healthy controls. However, while individuals with methamphetamine use disorders had higher BDI-II scores and individuals with cocaine use disorders had higher LSC–R scores, these findings did not reach statistical significance.

With regard to the differences in BDI-II scores, these findings may have treatment implications as those individuals who remained cocaine abstinent after treatment had lower rates of depression during the follow-up (McKay et al., 2013). Another report confirming the relationship between depression and substance use found that, in a sample of 146 methamphetamine using women, 60% met BDI-II criteria for moderate to severe depressive symptoms (Semple et al., 2007), while in a sample of 162 methamphetamine using men, 30% reported moderate to severe depressive symptoms (Peck et al., 2005). As such, data from the current study and other labs indicate that the presence and persistence of depressive symptoms may be associated with continued cocaine and methamphetamine use as well as potential relapse and the exacerbation of depressive symptoms in stimulant users when compared to controls.

The differences in BIS scores were also interesting given previous research on the topic. In one study, we found that cocaine- and methamphetamine-dependent individuals had BIS scores of ~72 and ~73, respectively, which is representative of high impulsivity (Tziortzis et al., 2011). Moreover, in methamphetamine (but not cocaine) users, after performing a median split, those with higher BIS scores also had significantly higher levels of craving demonstrating that impulsivity may impact subsequent drug taking (Tziortzis et al., 2011). More importantly, the data from that report indicate that more impulsive cocaine users exhibited more severe withdrawal, which has critical treatment implications since previous research has demonstrated that severity of cocaine withdrawal is a predictor of treatment retention and subsequent relapse (Kampman et al., 2001; Mulvaney et al., 1999). Related to this, the BIS motor score (assessing the tendency to act without thinking), predicted treatment completion for both cocaine- and methamphetamine-dependent patients (Winhusen et al., 2013). In addition, Miller and Gold (1994) assessed 1626 cocaine-dependent individuals at 6–12 months post-treatment and found that the most commonly cited reason for relapse was ‘impulsive action with no known cause’. Also, in a recently conducted study, recreational and dependent cocaine users endorsed higher levels of impulsivity when compared to healthy controls and, more importantly trait impulsivity scores were associated with an increased number of depressive symptoms (Vonmoos et al., 2013). Taken together, the increased impulsivity in stimulant users described in this report reveals that impulsivity may have important effects on continued drug use behavior.

As mentioned above, stress has also been related to cocaine craving. For example, in a number of experiments, stress imagery (recalling traumatic events) increased craving for cocaine (Sinha et al., 1999, 2000, 2003, 2005, 2007a, 2007b). While we did not detect a significant difference between cocaine users and controls in the current report with regard to LSC scores, methamphetamine users endorsed significantly higher number of life stressors and increased life stressors may account for their methamphetamine usage patterns.

Overall, the scores on these assessments are consistent with other studies in individuals with cocaine or methamphetamine use disorders conducted in our laboratory over the past several years, as well as other laboratories. For example, the overall score of our age matched individuals with cocaine or methamphetamine use disorders on the BDI-II was ~8–9, which is consistent with several other studies we have conducted (Culbertson et al., 2009; De La Garza et al., 2009; Kalechstein et al., 2009; Mahoney et al., 2012; Newton et al., 2009). In addition, BIS scores from the current study (~68–69 for individuals with cocaine or methamphetamine use disorders) were also consistent with our previously conducted research (~72–73; Tziortzis et al., 2011)). Moreover, our results are similar to other findings on impulsivity in cocaine-dependent subjects assessed in other laboratories, who also demonstrated higher scores on the BIS when compared to healthy controls (Ersche et al., 2010; Kjome et al., 2010; Moeller et al., 2002; Nielsen et al., 2012; Patkar et al., 2002, 2004; Walsh et al., 2010).

This study contained a number of strengths in comparison to other studies of its kind. For example, the use of a healthy control group for comparison to individuals with stimulant use disorders provides a better sense of how individuals with stimulant use disorders compare to the non-drug using population. In addition, all participants included were administered each of the assessments specified above so that direct comparisons could be made within and across groups. Despite the detailed and informative outcomes presented, some methodological limitations should be noted. First, this research design relied only on self-report measures; notwithstanding, self-reports have demonstrated reliability when confidentiality is ensured (Babor et al., 1990). Second, since some of the topics discussed in these assessments are sensitive in nature, there is the possibility of participant’s under-reporting their experiences. Third, consistency and inter-rater reliability were not assessed and measuring this component would provide beneficial insight for future studies. Another limitation is that we were unable to determine if symptoms of depression, impulsivity or lifetime stress were a result of ongoing drug use by the participants or if these symptoms preceded their drug use. In addition, we do not have additional information on socioeconomic status; however, we were able to demonstrate that education is weakly correlated with the scores on each of the assessments. Furthermore, while there is a significant difference between controls and cocaine and methamphetamine users with regard to years of education, it is difficult to determine whether or not this difference is clinically meaningful. An additional limitation is the difficulty interpreting the clinical significance of these findings. For example, while there was a clear and significant difference between healthy controls and those individuals with cocaine or methamphetamine use disorders, stimulant users still endorsed BDI score ~8–9, which were indicative of minimal depression. In addition, since there are no established cut-off scores for the other measures, the clinical significance of those findings are also somewhat unclear; however, the finding that stimulant users endorse greater impulsivity, life stress and sensation seeking is clearly evident. Despite these limitations, this study demonstrates that there are distinct behavioral differences between individuals with stimulant use disorders and healthy controls.

Footnotes

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Supported by NIH: DA027134 (RDLG); DA023468, DA18197 (TFN).

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