ORIGINAL RESEARCH
Relationship Between Coffee Use and Depression and Anxiety in a Population of Adult Polysubstance Abusers Errol Yudko, PhD, and Shannon Irena McNiece, MA
Objectives: This study examined the relationship between mental health symptoms and the use of tobacco and caffeinated beverages during and just before a counseling session in a population of adult polysubstance abusers. Methods: The participants were all polysubstance users in substance abuse treatment. The participants completed the Beck Depression Inventory II and the State-Trait Anxiety Inventory immediately after a treatment episode. They also reported whether or not they had drunk a caffeinated beverage or smoked a cigarette just before or during that treatment episode. Results: Coffee drinkers scored significantly higher (mean = 20.3) on the Beck Depression Inventory II than did noncoffee drinkers (mean = 9.2). The differences between these groups on the State-Trait Anxiety Inventory were nonsignificant. There was no relationship between other caffeinated beverages or tobacco use and depression or anxiety. Conclusions: Caffeine use is associated with depression in adult polysubstance abusers. Implications for using coffee drinking as a predictor of depression in substance abuse treatment settings are discussed. Key Words: anxiety, caffeine, coffee, comorbidity, co-occurring disorder, depression, dual diagnosis, energy drinks (J Addict Med 2014;8: 438–442)
T
he co-occurrence of mental health disorders with substance use disorders may be as high as 75% (see Sacks et al., 1997, for review). Adequately identifying whether a patient in treatment for issues related to substance use has a co-occurring diagnosis improves treatment outcomes (Center for Substance Abuse Treatment, 2005). Understanding behavioral predictors of mental health issues in substance-abusing clients can supplement the use of other diagnostic tools. Thus, better understanding behavioral predictors of mental health issues can improve treatment outcomes.
From the Department of Psychology, University of Hawai at Hilo, Hilo, HI. Received for publication February 26, 2014; accepted July 26, 2014. Supported by indirect costs from a grant obtained from the US Department of Health and Human Services. The authors declare no conflicts of interest. Send correspondence and reprint requests to Errol Yudko, PhD, University of Hawaii at Hilo, 200 W. Kawili St. Hilo, HI 96720. E-mail: errol @hawaii.edu. C 2014 American Society of Addiction Medicine Copyright ISSN: 1932-0620/14/0806-0438 DOI: 10.1097/ADM.0000000000000077
438
Several recent retrospective studies have supported the existence of an association between caffeine use and mental health problems. The authors of one such study concluded that it is possible that genetic factors contribute to both caffeine use and major depressive disorder (MDD) (Kendler et al., 2006). In a similar retrospective analysis (Bergin & Kendler, 2012), it was found that generalized anxiety disorder, MDD, and phobias shared genetic factors with caffeine use, but anorexia nervosa, bulimia nervosa, and panic disorder did not. Caffeine has indeed been shown to be mildly anxiogenic in doses of 300 mg or more (Childs & de Wit, 2006). This effect has been shown in a recent retrospective study (Trapp et al., 2014), an experimental study (Rogers, 2013), a physiological study (Rogers et al., 2010), and a review (Lara, 2010). This effect is fairly well established, and has been studied since the late 1960s (Goldstein et al., 1969). Caffeine is also anxiogenic in individuals who suffer from panic disorder (Charney et al., 1985; Breier et al., 1986; Nardi et al., 2007, 2008, 2009), performance social anxiety disorder (Nardi et al., 2009), and major depression with panic attacks (Nardi et al., 2007). It takes a large amount of caffeine to cause anxiety in normal individuals; for example, in Nardi’s studies 480 mg of caffeine (the equivalent of 4-5 cups of coffee) was enough to cause panic symptoms in patients with panic disorder and their first-degree relatives, but not in normal controls. The association between caffeine use and MDD is less clear than caffeine’s relationship to anxiety. In a retrospective study, Dosh et al., 2010 found that self-reported caffeine use was associated with depression in a sample of young adult smokers. There has been very limited work in this area. Almost all of the early research into the relationship between caffeine use and depression was retrospective (for review, see Clementz & Daily, 1988), showing only an association without any indication of the direction of causality. One early experimental study found that large doses of caffeine (the equivalent of 5 cups taken in a single beverage) caused depression-like symptoms (Veleber & Templer, 1984). However, more recent work has tended to refute this claim and suggests that caffeine use may be beneficial for sufferers of MDD (for review, see Lara, 2010). The current study used a prospective quasi-experimental design to study the relationship between caffeine use, during or just before attending substance abuse treatment, and mental health problems (depression and anxiety), in a sample of adult patients who were in treatment for substance abuse problems. Salivary cortisol was measured concurrently. J Addict Med r Volume 8, Number 6, November/December 2014
Copyright © 2014 American Society of Addiction Medicine. Unauthorized reproduction of this article is prohibited.
J Addict Med r Volume 8, Number 6, November/December 2014
MATERIALS AND METHODS Participants Information was collected from participants currently attending substance abuse treatment in a rural area in Hawaii. Participants were polydrug users. Eligibility criteria were relatively inclusive; inclusion criteria included being age of 18 years or more, being able to understand English, and having the ability to complete the survey scales without, or with minimal, assistance. There were 69 total participants in the research study—19 females and 50 males. The mean age for the total sample was 35.30 years (standard deviation = 13.34 years; age range = 18-76 years). The total sample was racially diverse (47.8% Pacific Islander, 46.4% European American/white, 26.1% Asian/Asian American, 20.3% Hispanic/ Latino, 8.7% American Indian or Alaskan Native, and 1.4% African American/black). Totals are greater than 100% because 38% of the sample indicated they were biracial or multiracial. Mean individual income was $11,260 and mean household income was $12,363. Thirty-two percent of the sample indicated they had a current psychiatric diagnosis. Twentyone percent of the sample was on medication for depression and/or anxiety. Participants were given a $10 gift card as incentive. Treatment of subjects was in accordance with the ethical standards of the American Psychological Association. This study was granted approval from the University of Hawai‘i Institutional Review Board Committee on Human Studies.
Materials The Beck Depression Inventory II (BDI-II) is a 21-item self-report measure designed by Beck et al. (1996). Each item is rated on a 4-point scale from 0 to 3. BDI-II total scores ranging from 0 to 13 represent “minimal” depression; scores from 14 to 19 are “mild” depression; scores from 20 to 28 are “moderate” depression; and, scores from 29 to 63 are “severe” depression (Beck et al., 1996). The BDI-II is a modified form of the BDI-IA. The BDI-IA was updated into the BDI-II to reflect changes in the depression criteria of the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition). The BDI-II is positively correlated with the Hamilton Rating Scale for Depression (Riskind et al., 1987, as cited in Beck et al., 1996). Good internal consistency and test-retest reliability have been adequately demonstrated with college and psychiatric samples (Beck et al., 1996). The BDI-II demonstrates reliable psychometric characteristics across clinical and nonclinical populations. The State-Trait Anxiety Inventory (STAI Form Y) is a 40-item, 4-point Likert self-report scale designed by Spielberger et al. (1970). The STAI Form Y is a modified form of the original STAI Form X (Spielberger & Vagg, 1984). The STAI Form Y has more stable factor loadings than the earlier version. There are 2 subscales. Each item of the S-Anxiety (state) scale is answered on a 4-point Likert scale (1 = not at all; 4 = very much so). Each item of the T-Anxiety (trait) scale is answered on a 4-point Likert scale (1 = almost never; 4 = almost always). Concurrent validity and internal consistency have been reliably demonstrated in this widely used inventory. C
Coffee Use, Depression, and Anxiety in Polysubstance Users
Additional Questions The subjects were asked several questions about recent behavior that could have altered cortisol levels. They were intended to be used as statistical controls. 1. Are you currently under emotional distress? Are you currently emotionally upset? 2. Have you had coffee to drink in the last hour? 3. Have you had any tea to drink in the last hour? 4. Have you had any kind of energy drink in the last hour? 5. Have you smoked cigarettes in the last hour?
Procedure The researcher went to the substance abuse treatment facilities at the convenience of those facilities. Data were collected over a period of 3 months. The researcher met with the participants immediately after a therapy session. Therapy sessions lasted for 1 hour. The researcher provided potential participants currently involved in substance abuse treatment with a brief description of the study. All willing participants were asked to complete informed consent, the BDI-II, STAI, and demographic information in paper-and-pencil format. Participants were informed that they had the option to stop the survey at any time, for any reason, and that they could leave any question blank for any reason. Participants were assigned subject numbers to protect confidentiality. All data were separated from informed consents and input into an SPSS (Statistical Package for the Social Sciences) database. Participants were given a copy of the consent form with researcher and institutional review board contact information. Participants were debriefed after completion of the survey packet. Saliva was collected by passive drooling into a tube that was immediately frozen at 0◦ C. Upon arrival at the laboratory, the tubes of saliva were centrifuged to remove sediment. The remainder was frozen at −20◦ C until assay. Each saliva sample was assayed twice to establish the reliability of measurement; analyses used the mean of the 2 values. The assay was a competitive enzyme immunoassay purchased from Salimetrics.
RESULTS Association Between Cortisol and BDI-II Scores/STAI T and S Scores Tests of the 3 a priori hypotheses of correlation were conducted using Bonferroni-adjusted alpha levels of 0.0167 per test (0.05/3). As can be seen from Table 1, there were positive significant bivariate correlations between BDI-II scores and both state (r = 0.514; P < 0.01) and trait (r = 0.664; P < 0.01) anxiety. There was also a significant positive correlation TABLE 1. Association Between Cortisol and BDI-II Score/STAI T and S Scores BDI-II State anxiety Trait anxiety
State Anxiety
Trait Anxiety
Mean Cortisol
0.514*
0.664* 0.665*
−0.031 −0.122 −0.071
*Correlation is significant at the 0.01 level (2-tailed). BDI-II, Beck Depression Inventory II; STAI, State-Trait Anxiety Inventory.
2014 American Society of Addiction Medicine
Copyright © 2014 American Society of Addiction Medicine. Unauthorized reproduction of this article is prohibited.
439
J Addict Med r Volume 8, Number 6, November/December 2014
Yudko and McNiece
between state and trait anxiety (r = 0.665; P < 0.01), but the relationship between cortisol and these scales was small and nonsignificant. A forward multiple regression was used to determine whether mean cortisol could predict anxiety or depression when distress, caffeine intake, smoking, and recent exercise (all factors know to cause changes in cortisol levels) were controlled for. There was still no association between the BDI-II score and cortisol level [R2 = 0.071; R2 adj = −0.073; F(7,46) = 0.492]; state anxiety and cortisol level [R2 = 0.067; R2 adj = −0.078; F(7,46) = 0.464]; or trait anxiety and cortisol level [R2 = 0.084; R2 adj = −0.055; F(7,46) = 0.602].
Other Factors Predicting Mental Health Variables Tests of the 15 a priori hypotheses were conducted using Bonferroni-adjusted alpha levels of 0.003 per test (0.05/15). As can be seen from Table 2, those participants who reported distress scored significantly higher on the BDI-II [t(63) = 4.276; P < 0.0001], STAI-S [t(63) = 6.0; P < 0.0001], and STAI-T [t(64) = 3.40; P < 0.0001] scales than those who did not. Furthermore, those participants who reported having had a coffee within 1 hour of testing (ie, immediately before, during, or just after therapy) scored significantly higher on the BDI-II [t(64) = 3.38; P < 0.001] than those who did not. Although there was a tendency for the coffee drinkers to score higher on the STAI-S and T scales, the difference scores did not reach an acceptable level of statistical significance (P > 0.05). Interestingly, neither energy drink users (P > 0.05) nor tea drinkers (P > 0.05) were significantly different from their nonusing counterparts on any of these measures. Although the sample sizes were small for both energy drink use and tea use, the differences were not even in the same directions as those for the coffee drinkers. Similarly, cigarette smokers (P > 0.05) did not differ from their nonusing counterparts on any of these measures.
DISCUSSION The average participant who drank coffee just before, or during, their treatment session scored as moderately depressed on the BDI-II. This is in comparison with the average noncoffee drinker who was only minimally depressed (the lowest category that the BDI-II yields). Table 3 shows the proportion of coffee drinkers and noncoffee drinkers who scored in each of the 4 categories of the BDI-II. To our knowledge, this is the first time this effect has been shown in a prospective study of adult substance users. Another way to look at this phenomenon is that 89% of the 36 participants who were minimally depressed did not drink coffee during, or just before, their counseling sessions. In other words, there would be very few false negatives if coffee drinking was used to predict depression in a substanceabusing population. Up to 73% of coffee drinkers were classified as depressed by the BDI-II. In other words, coffee drinking just before or during counseling sessions is a fairly sensitive measure of depression. In fact, only 37% of the depressed participants (those who scored ≥15 on the BDI-II) did not drink coffee during or before their counseling sessions. Thus, coffee drinking during counseling as a predictor of depression has a
440
TABLE 2. Mental Health Variables n
Mean
t
P
1. Are you currently under emotional distress or emotionally upset? BDI Yes 24 20.30 (2.59) t(63) = 4.276 P < 0.0001 No 41 9.20 (1.28) State anxiety Yes 24 47.58 (2.07) t(63) = 6.0 P < 0.0001 No 41 32.90 (1.43) Trait anxiety Yes 23 47.09 (1.94) t(64) = 3.40 P < 0.0001 No 43 38.44 (1.54) 2. Have you had coffee to drink in the last hour? BDI Yes 15 21.29 (3.95) t(64) = 3.38 p
Relationship Between Coffee Use and Depression and Anxiety in a Population of Adult Polysubstance Abusers Errol Yudko, PhD, and Shannon Irena McNiece, MA
Objectives: This study examined the relationship between mental health symptoms and the use of tobacco and caffeinated beverages during and just before a counseling session in a population of adult polysubstance abusers. Methods: The participants were all polysubstance users in substance abuse treatment. The participants completed the Beck Depression Inventory II and the State-Trait Anxiety Inventory immediately after a treatment episode. They also reported whether or not they had drunk a caffeinated beverage or smoked a cigarette just before or during that treatment episode. Results: Coffee drinkers scored significantly higher (mean = 20.3) on the Beck Depression Inventory II than did noncoffee drinkers (mean = 9.2). The differences between these groups on the State-Trait Anxiety Inventory were nonsignificant. There was no relationship between other caffeinated beverages or tobacco use and depression or anxiety. Conclusions: Caffeine use is associated with depression in adult polysubstance abusers. Implications for using coffee drinking as a predictor of depression in substance abuse treatment settings are discussed. Key Words: anxiety, caffeine, coffee, comorbidity, co-occurring disorder, depression, dual diagnosis, energy drinks (J Addict Med 2014;8: 438–442)
T
he co-occurrence of mental health disorders with substance use disorders may be as high as 75% (see Sacks et al., 1997, for review). Adequately identifying whether a patient in treatment for issues related to substance use has a co-occurring diagnosis improves treatment outcomes (Center for Substance Abuse Treatment, 2005). Understanding behavioral predictors of mental health issues in substance-abusing clients can supplement the use of other diagnostic tools. Thus, better understanding behavioral predictors of mental health issues can improve treatment outcomes.
From the Department of Psychology, University of Hawai at Hilo, Hilo, HI. Received for publication February 26, 2014; accepted July 26, 2014. Supported by indirect costs from a grant obtained from the US Department of Health and Human Services. The authors declare no conflicts of interest. Send correspondence and reprint requests to Errol Yudko, PhD, University of Hawaii at Hilo, 200 W. Kawili St. Hilo, HI 96720. E-mail: errol @hawaii.edu. C 2014 American Society of Addiction Medicine Copyright ISSN: 1932-0620/14/0806-0438 DOI: 10.1097/ADM.0000000000000077
438
Several recent retrospective studies have supported the existence of an association between caffeine use and mental health problems. The authors of one such study concluded that it is possible that genetic factors contribute to both caffeine use and major depressive disorder (MDD) (Kendler et al., 2006). In a similar retrospective analysis (Bergin & Kendler, 2012), it was found that generalized anxiety disorder, MDD, and phobias shared genetic factors with caffeine use, but anorexia nervosa, bulimia nervosa, and panic disorder did not. Caffeine has indeed been shown to be mildly anxiogenic in doses of 300 mg or more (Childs & de Wit, 2006). This effect has been shown in a recent retrospective study (Trapp et al., 2014), an experimental study (Rogers, 2013), a physiological study (Rogers et al., 2010), and a review (Lara, 2010). This effect is fairly well established, and has been studied since the late 1960s (Goldstein et al., 1969). Caffeine is also anxiogenic in individuals who suffer from panic disorder (Charney et al., 1985; Breier et al., 1986; Nardi et al., 2007, 2008, 2009), performance social anxiety disorder (Nardi et al., 2009), and major depression with panic attacks (Nardi et al., 2007). It takes a large amount of caffeine to cause anxiety in normal individuals; for example, in Nardi’s studies 480 mg of caffeine (the equivalent of 4-5 cups of coffee) was enough to cause panic symptoms in patients with panic disorder and their first-degree relatives, but not in normal controls. The association between caffeine use and MDD is less clear than caffeine’s relationship to anxiety. In a retrospective study, Dosh et al., 2010 found that self-reported caffeine use was associated with depression in a sample of young adult smokers. There has been very limited work in this area. Almost all of the early research into the relationship between caffeine use and depression was retrospective (for review, see Clementz & Daily, 1988), showing only an association without any indication of the direction of causality. One early experimental study found that large doses of caffeine (the equivalent of 5 cups taken in a single beverage) caused depression-like symptoms (Veleber & Templer, 1984). However, more recent work has tended to refute this claim and suggests that caffeine use may be beneficial for sufferers of MDD (for review, see Lara, 2010). The current study used a prospective quasi-experimental design to study the relationship between caffeine use, during or just before attending substance abuse treatment, and mental health problems (depression and anxiety), in a sample of adult patients who were in treatment for substance abuse problems. Salivary cortisol was measured concurrently. J Addict Med r Volume 8, Number 6, November/December 2014
Copyright © 2014 American Society of Addiction Medicine. Unauthorized reproduction of this article is prohibited.
J Addict Med r Volume 8, Number 6, November/December 2014
MATERIALS AND METHODS Participants Information was collected from participants currently attending substance abuse treatment in a rural area in Hawaii. Participants were polydrug users. Eligibility criteria were relatively inclusive; inclusion criteria included being age of 18 years or more, being able to understand English, and having the ability to complete the survey scales without, or with minimal, assistance. There were 69 total participants in the research study—19 females and 50 males. The mean age for the total sample was 35.30 years (standard deviation = 13.34 years; age range = 18-76 years). The total sample was racially diverse (47.8% Pacific Islander, 46.4% European American/white, 26.1% Asian/Asian American, 20.3% Hispanic/ Latino, 8.7% American Indian or Alaskan Native, and 1.4% African American/black). Totals are greater than 100% because 38% of the sample indicated they were biracial or multiracial. Mean individual income was $11,260 and mean household income was $12,363. Thirty-two percent of the sample indicated they had a current psychiatric diagnosis. Twentyone percent of the sample was on medication for depression and/or anxiety. Participants were given a $10 gift card as incentive. Treatment of subjects was in accordance with the ethical standards of the American Psychological Association. This study was granted approval from the University of Hawai‘i Institutional Review Board Committee on Human Studies.
Materials The Beck Depression Inventory II (BDI-II) is a 21-item self-report measure designed by Beck et al. (1996). Each item is rated on a 4-point scale from 0 to 3. BDI-II total scores ranging from 0 to 13 represent “minimal” depression; scores from 14 to 19 are “mild” depression; scores from 20 to 28 are “moderate” depression; and, scores from 29 to 63 are “severe” depression (Beck et al., 1996). The BDI-II is a modified form of the BDI-IA. The BDI-IA was updated into the BDI-II to reflect changes in the depression criteria of the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition). The BDI-II is positively correlated with the Hamilton Rating Scale for Depression (Riskind et al., 1987, as cited in Beck et al., 1996). Good internal consistency and test-retest reliability have been adequately demonstrated with college and psychiatric samples (Beck et al., 1996). The BDI-II demonstrates reliable psychometric characteristics across clinical and nonclinical populations. The State-Trait Anxiety Inventory (STAI Form Y) is a 40-item, 4-point Likert self-report scale designed by Spielberger et al. (1970). The STAI Form Y is a modified form of the original STAI Form X (Spielberger & Vagg, 1984). The STAI Form Y has more stable factor loadings than the earlier version. There are 2 subscales. Each item of the S-Anxiety (state) scale is answered on a 4-point Likert scale (1 = not at all; 4 = very much so). Each item of the T-Anxiety (trait) scale is answered on a 4-point Likert scale (1 = almost never; 4 = almost always). Concurrent validity and internal consistency have been reliably demonstrated in this widely used inventory. C
Coffee Use, Depression, and Anxiety in Polysubstance Users
Additional Questions The subjects were asked several questions about recent behavior that could have altered cortisol levels. They were intended to be used as statistical controls. 1. Are you currently under emotional distress? Are you currently emotionally upset? 2. Have you had coffee to drink in the last hour? 3. Have you had any tea to drink in the last hour? 4. Have you had any kind of energy drink in the last hour? 5. Have you smoked cigarettes in the last hour?
Procedure The researcher went to the substance abuse treatment facilities at the convenience of those facilities. Data were collected over a period of 3 months. The researcher met with the participants immediately after a therapy session. Therapy sessions lasted for 1 hour. The researcher provided potential participants currently involved in substance abuse treatment with a brief description of the study. All willing participants were asked to complete informed consent, the BDI-II, STAI, and demographic information in paper-and-pencil format. Participants were informed that they had the option to stop the survey at any time, for any reason, and that they could leave any question blank for any reason. Participants were assigned subject numbers to protect confidentiality. All data were separated from informed consents and input into an SPSS (Statistical Package for the Social Sciences) database. Participants were given a copy of the consent form with researcher and institutional review board contact information. Participants were debriefed after completion of the survey packet. Saliva was collected by passive drooling into a tube that was immediately frozen at 0◦ C. Upon arrival at the laboratory, the tubes of saliva were centrifuged to remove sediment. The remainder was frozen at −20◦ C until assay. Each saliva sample was assayed twice to establish the reliability of measurement; analyses used the mean of the 2 values. The assay was a competitive enzyme immunoassay purchased from Salimetrics.
RESULTS Association Between Cortisol and BDI-II Scores/STAI T and S Scores Tests of the 3 a priori hypotheses of correlation were conducted using Bonferroni-adjusted alpha levels of 0.0167 per test (0.05/3). As can be seen from Table 1, there were positive significant bivariate correlations between BDI-II scores and both state (r = 0.514; P < 0.01) and trait (r = 0.664; P < 0.01) anxiety. There was also a significant positive correlation TABLE 1. Association Between Cortisol and BDI-II Score/STAI T and S Scores BDI-II State anxiety Trait anxiety
State Anxiety
Trait Anxiety
Mean Cortisol
0.514*
0.664* 0.665*
−0.031 −0.122 −0.071
*Correlation is significant at the 0.01 level (2-tailed). BDI-II, Beck Depression Inventory II; STAI, State-Trait Anxiety Inventory.
2014 American Society of Addiction Medicine
Copyright © 2014 American Society of Addiction Medicine. Unauthorized reproduction of this article is prohibited.
439
J Addict Med r Volume 8, Number 6, November/December 2014
Yudko and McNiece
between state and trait anxiety (r = 0.665; P < 0.01), but the relationship between cortisol and these scales was small and nonsignificant. A forward multiple regression was used to determine whether mean cortisol could predict anxiety or depression when distress, caffeine intake, smoking, and recent exercise (all factors know to cause changes in cortisol levels) were controlled for. There was still no association between the BDI-II score and cortisol level [R2 = 0.071; R2 adj = −0.073; F(7,46) = 0.492]; state anxiety and cortisol level [R2 = 0.067; R2 adj = −0.078; F(7,46) = 0.464]; or trait anxiety and cortisol level [R2 = 0.084; R2 adj = −0.055; F(7,46) = 0.602].
Other Factors Predicting Mental Health Variables Tests of the 15 a priori hypotheses were conducted using Bonferroni-adjusted alpha levels of 0.003 per test (0.05/15). As can be seen from Table 2, those participants who reported distress scored significantly higher on the BDI-II [t(63) = 4.276; P < 0.0001], STAI-S [t(63) = 6.0; P < 0.0001], and STAI-T [t(64) = 3.40; P < 0.0001] scales than those who did not. Furthermore, those participants who reported having had a coffee within 1 hour of testing (ie, immediately before, during, or just after therapy) scored significantly higher on the BDI-II [t(64) = 3.38; P < 0.001] than those who did not. Although there was a tendency for the coffee drinkers to score higher on the STAI-S and T scales, the difference scores did not reach an acceptable level of statistical significance (P > 0.05). Interestingly, neither energy drink users (P > 0.05) nor tea drinkers (P > 0.05) were significantly different from their nonusing counterparts on any of these measures. Although the sample sizes were small for both energy drink use and tea use, the differences were not even in the same directions as those for the coffee drinkers. Similarly, cigarette smokers (P > 0.05) did not differ from their nonusing counterparts on any of these measures.
DISCUSSION The average participant who drank coffee just before, or during, their treatment session scored as moderately depressed on the BDI-II. This is in comparison with the average noncoffee drinker who was only minimally depressed (the lowest category that the BDI-II yields). Table 3 shows the proportion of coffee drinkers and noncoffee drinkers who scored in each of the 4 categories of the BDI-II. To our knowledge, this is the first time this effect has been shown in a prospective study of adult substance users. Another way to look at this phenomenon is that 89% of the 36 participants who were minimally depressed did not drink coffee during, or just before, their counseling sessions. In other words, there would be very few false negatives if coffee drinking was used to predict depression in a substanceabusing population. Up to 73% of coffee drinkers were classified as depressed by the BDI-II. In other words, coffee drinking just before or during counseling sessions is a fairly sensitive measure of depression. In fact, only 37% of the depressed participants (those who scored ≥15 on the BDI-II) did not drink coffee during or before their counseling sessions. Thus, coffee drinking during counseling as a predictor of depression has a
440
TABLE 2. Mental Health Variables n
Mean
t
P
1. Are you currently under emotional distress or emotionally upset? BDI Yes 24 20.30 (2.59) t(63) = 4.276 P < 0.0001 No 41 9.20 (1.28) State anxiety Yes 24 47.58 (2.07) t(63) = 6.0 P < 0.0001 No 41 32.90 (1.43) Trait anxiety Yes 23 47.09 (1.94) t(64) = 3.40 P < 0.0001 No 43 38.44 (1.54) 2. Have you had coffee to drink in the last hour? BDI Yes 15 21.29 (3.95) t(64) = 3.38 p
