Comorbidity of Major Depression With Substance Use Disorders

Transcription

1 CAPE Special Issue Comorbidity of Major Depression With Substance Use Disorders Shawn R Currie, PhD, RPsych 1, Scott B Patten, MD, FRCPC, PhD 2, Jeanne VA Williams, BA, MSc 3, JianLi Wang, PhD 4, Cynthia A Beck, MD, FRCPC, MASc 5, Nady El-Guebaly, MD, FRCPC 6, Colleen Maxwell, BSc 7 Objectives: In the Canadian adult population, we aimed to 1) estimate the 12-month prevalence of major depressive disorder (MDD) in persons with a diagnosis of harmful alcohol use, alcohol, and drug ; 2) estimate the 12-month prevalence of harmful alcohol use, alcohol, and drug in persons with a 12-month and lifetime diagnosis of MDD; 3) identify socioeconomic correlates of substance use disorder major depression comorbidity; 4) determine how comorbidity impacts the prevalence of suicidal thoughts; and 5) determine how comorbidity affects mental health care used. Methods: We examined data from the Canadian Community Health Survey: Mental Health and Well-Being (CCHS 1.2). Results: The 12-month prevalences of MDD in persons with a substance use disorder (SUD) were 6.9% for harmful alcohol use (95% confidence interval [CI], 5.2 to 8.5), 8.8% for alcohol (95%CI, 6.6 to 11.0), and 16.1% for drug (95%CI, 10.3 to 21.9). Conversely, the 12-month prevalences of harmful alcohol use, alcohol, and drug in persons with a 12-month diagnosis of MDD were 12.3% (95%CI, 9.4 to 15.2), 5.8% (95%CI, 4.3 to 7.3), and 3.2% (95%CI, 2.0 to 4.4), respectively. Regression modelling did not identify any socioeconomic predictors of SUD MDD comorbidity. Substance and MDD independently predicted higher prevalence of suicidal thoughts and mental health treatment use. Conclusions: SUDs cooccur with a high frequency in cases of MDD. Clinicians and mental health services should consider routine assessment of SUDs in depression patients. (Can J Psychiatry 2005;50: ) Information on funding and support and author affiliations appears at the end of the article. Clinical Implications SUDs are more common in persons with current and lifetime MDD than in persons with no history of MDD. Clinicians should routinely assess for concurrent SUDs in depression patients and vice versa. Compared with nondependent individuals, substance is associated with an almost threefold increase in MDD and a fourfold increase in suicidal thoughts. Addiction therapists should routinely inquire about suicidal ideation. Risk of MDD and suicidal thoughts appears to increase with more severe involvement in substance use (lowest for harmful alcohol use, intermediate for alcohol, and highest for drug ). Limitations The CCHS 1.2 did not assess lifetime prevalence of SUDs, precluding any examination of the temporal priority of MDD or SUD in age of onset. The CCHS 1.2 did not assess prescription drug abuse or tobacco. The cross-sectional nature of the CCHS 1.2 precludes any examination of causal factors in the development of MDD SUD comorbidity. 660

2 Comorbidity of Major Depression With Substance Use Disorders Key Words: comorbidity, major depression, substance use disorder, suicide ideation Interest in the comorbidity of mental disorders has gained momentum in the last decade. The 2 most common mental disorders in North America are major depression and substance. Not surprisingly, these disorders tend to coexist, particularly in treatment-seeking patients (1 3). There remains some uncertainty regarding the true frequency of cooccurring major depression and SUDs in the general population. Studies conducted over the last 15 years have produced a range of comorbidity prevalence rates (1,4,5). The original NCS in the US found that 18% of individuals with a 12-month diagnosis of MDD had at least one SUD (6). Conversely, about 23% of persons with a 12-month SUD reported major depression during the same period. These estimates were slightly lower than reported from the ECA study conducted earlier (7). Comorbidity rates in the 2001 NCS-R fell between the NCS and ECA rates (6), although the rates for specific SUDs (that is, alcohol or drugs) have yet to be released. In the most recent US study, the NESARC (1), the prevalence of MDD in individuals with a 12-month SUD ranged from 8% for alcohol abuse to 40% for drug. Among individuals with a 12-month MDD, the prevalence rate of SUDs ranged from 8% for alcohol abuse to 19% for any SUD. One explanation for the variability is the fact that the diagnostic criteria for MDD and the SUDs have changed over time. This would affect the prevalence rates for individual disorders Abbreviations used in this article AUDADIS CCHS 1.2 CI CIDI CL ECA MDD MDMA NCS NCS-R NESARC NS OR SUD WMH-CIDI Alcohol Use Disorder and Associated Disabilities Interview Schedule Canadian Community Health Survey: Mental Health and Well-Being confidence interval Composite International Diagnostic Interview common law Epidemiological Catchment Area major depressive disorder 3,4-methylenedioxymethamphetamine National Comorbidity Survey National Comorbidity Survey-Replication National Epidemiologic Survey on Alcohol and Related Conditions not significant odds ratio substance use disorder World Mental Health Composite International Diagnostic Interview and possibly amplify the effect for comorbidity. Second, epidemiologic surveys have used different instruments. Improvements in the CIDI, resulting in fewer false positives, are thought to account for the lower frequency of comorbidity in the NCS-R (4). Further, direct comparisons of diagnoses derived from various epidemiologic interviews have produced different SUD prevalences in the same sample (8,9). Third, surveys have differed in their management of overlapping symptoms. Many of the symptoms of intoxication and withdrawal can mimic the symptoms of major depression. Most household surveys do not include the necessary probe questions to determine whether symptoms are substanceinduced or part of an independent disorder. The NESARC purportedly used a better interview (the AUDADIS) to disentangle overlapping symptoms present in both disorders. Investigators concluded that fewer than 1% of mood disorders are actually substance-induced (1). For most SUD cases, the mood disorder persisted during periods of abstinence or began before the onset of problematic substance use. Until the release of the CCHS 1.2, there were no national population data on comorbidity in Canada. Early epidemiologic studies were limited to Edmonton (10) and Ontario (11). The specific objectives of this analysis were as follows: 1. To estimate the 12-month prevalence of MDD within persons with a 12-month diagnosis of harmful alcohol abuse, alcohol, and drug. 2. To estimate the 12-month prevalence of alcohol, harmful alcohol abuse, and drug in persons with a 12-month and lifetime diagnosis of MDD. 3. To identify socioeconomic correlates of SUD MDD comorbidity. 4. To determine the impact of comorbidity on reporting of suicidal thoughts. 5. To determine the impact of comorbidity on mental health service use. Methods The CCHS 1.2 Detailed descriptions of the CCHS 1.2 in terms of target population, sampling procedures, response rate, and psychiatric assessment are provided in a separate article in this issue (12). Briefly, the CCHS 1.2 was a cross-sectional survey of a nationally representative sample of individuals aged 15 years and over (13). The CCHS 1.2 data were collected by Statistics Canada between May and December 2002 (n = ). Major Depression A Canadian adaptation of the WMH-CIDI (14) assessed DSM-IV defined major depressive episodes. For the present Can J Psychiatry, Vol 50, No 10, September

3 The Canadian Journal of Psychiatry CAPE Special Issue Table 1 Prevalence of SUDs, MDD, and associated comorbidity in the Canadian population Independent disorders SUD analysis, our interest was in the lifetime and 12-month presentation of unipolar MDD. Hence, individuals with bipolar disorder are not included in the prevalence. Substance Use Disorders Twelve-month, but not lifetime, diagnoses for the SUDs were assessed in the CCHS 1.2. The WMH-CIDI s assessment of alcohol was based on DSM-III-R criteria (15). The alcohol scale from the CIDI Short Form was tested extensively during the NCS (6,16). Alcohol, as defined in the CCHS 1.2, represents a purported 85% predictive cut point, which corresponds to reporting at least 3 symptoms from the DSM criteria. Unfortunately, the CCHS 1.2 did not provide full coverage of DSM symptoms for alcohol abuse. Therefore, we developed a separate algorithm for defining harmful alcohol use on the basis of ICD-10 criteria (17). These criteria include the following: 1) alcohol use contributing to physical or psychological harm, leading to disability or adverse consequences; 2) the nature of the harm 662 Harmful alcohol use Alcohol Drug Alcohol or drug Major depression Major depression (lifetime) Harmful alcohol use Alcohol Drug Alcohol or drug Prevalence % (95%CI) 7.0 ( ) 2.6 ( ) 0.8 ( ) 3.1 ( ) 4.0 ( ) 10.8 ( ) Comorbidity prevalence % (95%CI) In persons with MDD MDD within SUD 12.3 ( ) 6.9 ( ) 5.8 ( ) 8.8 ( ) 3.2 ( ) 16.1 ( ) 7.4 ( ) 9.6 ( ) Twelve-month prevalence rates shown unless otherwise indicated is identifiable; 3) the pattern of use persisted for at least 1 month; and 4) symptoms do not meet criteria for alcohol. The CCHS 1.2 provided complete coverage of these symptoms. The illicit drug section of the CCHS 1.2 did not provide sufficient coverage of symptoms to define a category of harmful drug use but did cover all the DSM-IV items for drug. The specific substances covered were cannabis, cocaine, amphetamines, MDMA, hallucinogens, solvents, heroin, and steroids, although our analysis focused on any drug. Other Measures Other variables included in this analysis are demographics, suicidal thoughts in the past 12 months, and use of any health services, specifically for a problem concerning emotions, mental health, or use of alcohol and drugs in the past 12 months. Statistical Analysis All statistical analyses were carried out with SAS/STAT 8.02 (18); we used the sampling weights and bootstrap weights provided by Statistics Canada to account for the complex sampling procedure. Comorbidity estimates derived from subsamples of respondents who provided valid responses to major depression and the specific SUDs under investigation. For each analysis, we used the full sample available. The rate for missing data owing to nonresponse or refusal in the CCHS 1.2 was low (< 1%). Consistent with other epidemiologic studies in the area, comorbidity was defined as major depression and an SUD occurring within the same 12-month time period (1). Results The individual prevalence rates for SUDs (12-month), MDD (12-month and lifetime), and associated comorbidity are provided in Table 1. Rates of MDD were 2 to 4 times higher in persons with an SUD, compared with the general population. The CCHS 1.2 results are displayed with comparison data from the original NCS (6) and NESARC (1) in Figures 1 and 2. Lifetime prevalence was available only for MDD. In persons with no history of MDD, the 12-month prevalence of alcohol or drug was 2.9%, compared with 4.8% for persons with a lifetime MDD history. The lifetime MDD prevalence in persons with 12-month SUD diagnosis was 13.9% for harmful alcohol use, 16.3% for alcohol, 21.2% for drug, and 16.9% for alcohol or drug. Note that the comorbidity estimates for the alcohol or drug category represent a weighted proportion of the individual alcohol and drug estimates (thus the value falls between the alcohol and drug estimates, instead of being higher).

4 Comorbidity of Major Depression With Substance Use Disorders Figure 1 Twelve-month prevalence of SUDs in persons with a 12-month prevalence of MDD across the CCHS, NCS (6), and NESARC (1). Prevalence on any substance not available for NCS 12-month prevalence of SUD Harmful ETOH use/alcohol abuse Drug ETOH Alcohol or drug NCS 1992 CCHS 2002 NESARC 2002 Figure 2 Twelve-month prevalence of MDD in persons with harmful alcohol use, drug, alcohol, and any substance in the CCHS, NCS (6), and NESARC (1) 12-month prevalence of SUD General population ETOH Alcohol or drug Harmful ETOH use/alcohol abuse Drug NCS 1992 CCHS 2002 NESARC 2002 In logistic regression modelling, the 12-month prevalence of MDD was predicted by the demographic variables of age, sex, and marital status (income, education, and urban vs rural residence were not significant predictors). In the presence of these variables, an SUD increased the chances of MDD by factors ranging from 2.1 (harmful alcohol use) to 4.3 (drug ). No interactions were found between demographics and the specific SUDs in predicting MDD. These results are summarized in Table 2. The impact of cooccurring SUD and MDD on reports of suicidal thoughts was similarly studied through logistic modelling. As shown in Table 3, MDD, alcohol, and drug all independently predict suicidal thoughts in the past 12 months, with MDD being the strongest predictor. The SUD MDD interaction terms in the models were not significant; however, the fitted proportions from the reduced model indicated that the risk of suicidal thoughts was indeed higher in comorbid subjects. For example, individuals experiencing both MDD and alcohol in the last 12 months were at least 20 times more likely to have suicidal ideation, compared with individuals with neither condition. The same trend emerged with drug. Harmful alcohol use, however, was not associated with suicidal thoughts. A similar pattern emerged with mental health service use. Alcohol, drug, and MDD all independently predicted greater use of mental health services in the last 12 months (ORs 3.1, 6.4, and 14.9, respectively), compared with persons without these disorders. Harmful alcohol use was not associated with greater mental health services, and no SUD-by-MDD interactions were found. Discussion Consistent with other population surveys (1,4,6), persons with major depression are more likely to report an SUD than are persons with no depression. Further, risk of harmful alcohol use and alcohol is 2 times greater for persons with major depression. Drug was 4 times more likely in individuals with major depression and increased the chances of reporting suicidal thoughts by a factor of 5. The lifetime prevalence of major depression in persons with alcohol or drug was about 17%, compared with about 11% in persons with no substance disorder. No demographic correlates of MDD SUD comorbidity emerged among those studied. Harmful alcohol use and substance independently predicted MDD with no interaction with sex, age, or marital status. We found no significant interaction between SUD and MDD in predicting Can J Psychiatry, Vol 50, No 10, September

5 The Canadian Journal of Psychiatry CAPE Special Issue Table 2 Predicting 12-month MDD from SUD Model 1 Demographics, harmful alcohol use Model 2 Demographics, alcohol Model 3 Demographics, drug Model 4 Demographics, alcohol or drug Covariate OR 95%CI P OR 95%CI P OR 95%CI P OR 95%CI P Female sex Age a Marital status b Harmful alcohol use Alcohol Drug Alcohol or drug a 0=>45years, 1=15to45years. b 0 = Single or married or CL, 1 = widowed or separated or divorced; = variable not included in the model suicidal thoughts or mental health service use. Consistent with other research (19), the presence of both conditions during the same 12-month period increased the prevalence of suicidal thoughts in a multiplicative fashion. Estimating the exact frequency of suicidal thoughts associated with comorbidity is difficult because of the lack of statistical precision in the fitted proportions. Nevertheless, risk of suicidal thoughts in persons with both substance and MDD may be dramatically higher than in persons with neither condition. A similar trend was observed with mental health service use. The clinical implication of these results is that comorbidity is associated with greater psychological distress than either condition alone. Fortunately, this appears to be directing individuals to seek professional assistance. Harmful alcohol use was neither associated with suicidal thoughts nor with mental health service use. The latter finding is not surprising given that persons with alcohol abuse disorders are not likely to seek treatment (20). Conversely, harmful alcohol use is associated with a twofold increase in MDD, suggesting that this is a vulnerable group for mental illness that is unlikely to be identified by mental health providers. Further, the prevalence of harmful alcohol use is more than 2 times higher than the prevalence of, indicating a large group of at-risk individuals who are unlikely to seek treatment. Many of the comorbidity estimates in the CCHS 1.2 are noticeably lower than estimates reported in US surveys. For example, the rates of alcohol and drug in persons with MDD were less than one-half the rates reported in the 664 NCS and NESARC. We can only speculate on the reasons for these differences. The simplest explanation is that comorbidity is less common in Canada than in the US. Both 12-month and lifetime rates of major depression are lower in the CCHS 1.2, compared with the NCS and the NESARC (1,21). Conversely, the prevalence rates of the SUDs are similar to the NESARC findings (2.6% compared with 3.8% and 0.8 compared with 0.7% for alcohol and drug, respectively). Socioeconomic differences between the US and Canada or between the study samples could account for the discrepant prevalence rates in MDD and its associated comorbidity. Another reason could be methodological. The CCHS 1.2 and the NESARC employed different diagnostic instruments (the CIDI and the AUDADIS). In direct comparisons, the AUDADIS has produced higher rates of alcohol than the CIDI (8,9) in the same sample, most likely because of the stronger focus on alcohol in the AUDADIS. Finally, the CIDI used in the CCHS 1.2 relied on the DSM-III-R criteria for alcohol, whereas the NCS-R and NESARC employed DSM-IV criteria. Although the absolute prevalence rates between Canada and the US diverge, the pattern of results is similar. The prevalence of major depression within alcohol and drug is higher than the prevalence of alcohol and drug within major depression. Further, drug was associated with the highest rate of concurrent MDD across all surveys (1,6). The prevalence of MDD in individuals with drug was almost twice the rate in individuals with alcohol. Although cause and effect

6 Comorbidity of Major Depression With Substance Use Disorders Table 3 Predicting suicidal thoughts from MDD and SUD Model 1 harmful alcohol use Model 2 alcohol Model 3 drug Model 4 alcohol or drug Covariate OR 95%CI P OR 95%CI P OR 95%CI P OR 95% CI P Female sex NS NS NS NS Age a NS NS NS Marital status b MDD Harmful alcohol use NS Alcohol Drug Alcohol or drug a 0=>45years, 1=15to45years. b 0 = Single or married or CL, 1 = widowed or separated or divorced; = variable not included in the model cannot be assumed in this association, it is possible that persons with more psychopathology gravitate toward harder drugs as a form of self-medication. Further analysis of the CCHS 1.2 may shed some light on the relation between drug and major depression. Nevertheless, the elucidation of etiologic factors will be limited, given that the survey is cross-sectional. Notable limitations of this analysis are the absence of any lifetime prevalence estimates for the SUDs, the use of our own algorithm for defining harmful alcohol use, and the limited coverage of drugs in the assessment of. The absence of lifetime questions concerning substance use precluded any examination of the temporal priority of MDD or SUD in age of onset. Other epidemiologic data suggest an earlier onset of major depression, compared with problematic substance use (4,6), but we are unable to corroborate this finding with Canadian estimates. Our definition of harmful alcohol use complies with the content of the ICD-10 diagnostic criteria, but it has not been validated. The symptom profile of harmful alcohol use is similar to alcohol abuse (17); however, direct comparisons of diagnoses deriving from the criteria have yielded poor concordance (8,9). Further, the interrater reliabilities for the alcohol abuse and harmful use categories have been historically poor (22). Finally, the coverage of the CCHS 1.2 drug module was limited to illicit drugs; hence, abuse of prescription narcotics and sedative drugs was not captured. This is unfortunate because Canada is the largest per capita consumer of codeine and the third largest per capita consumer of morphine in the world (23). Substance has been shown to complicate the course of major depression, diminish treatment response, increase the chronicity of the mood disorder, and increase the level of psychological stress experienced by the individual (2,24). Risk of MDD and suicidal thoughts appears to increase with more severe involvement in substance use (lowest for harmful alcohol use, intermediate for alcohol, and highest for drug ). Clinicians should routinely assess for SUDs in depression patients. Greater integration of mental health and addiction treatment services could improve the management of both disorders. Disclaimer Some of the data upon which the analyses contained in this paper derive from surveys conducted by Statistics Canada. The opinions expressed in this paper do not represent the opinions of Statistics Canada Funding and Support This project was supported by an operating grant from the Canadian Institutes of Health Research. References 1. Grant BF, Stinson FS, Dawson DA, Chou SP, Dufour MC, Compton W, and others. Prevalence and co-occurrence of substance use disorders and independent mood and anxiety disorders. Arch Gen Psychiatry 2004;61: Galbaud du Fort G, Newman SC, Boothroyd LJ, Bland RC. Treatment seeking for depression: role of depressive symptoms and comorbid psychiatric diagnoses. J Affect Disord 1999;52: Can J Psychiatry, Vol 50, No 10, September

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Arch Gen Psychiatry 2002;59: Manuscript received and accepted May This research was presented in part at the Canadian Academy for Psychiatric Epidemiology 2004 Annual Scientific Symposium; 2004 October 14, Montreal (QC). 1 Adjunct Associate Professor, Departments of Psychiatry and Psychology, University of Calgary, Calgary, Alberta. 2 Associate Professor, Departments of Community Health Sciences and Psychiatry, University of Calgary, Calgary, Alberta. 3 Research Associate, Department of Psychiatry, University of Calgary, Calgary, Alberta. 4 Assistant Professor, Departments of Community Health Sciences and Psychiatry, University of Calgary, Calgary, Alberta. 5 Assistant Professor, Department of Psychiatry, University of Calgary, Calgary, Alberta. 6 Professor, Department of Psychiatry, University of Calgary, Calgary, Alberta. 7 Associate Professor, Department of Community Health Sciences, University of Calgary, Calgary, Alberta. Address for Correspondence: Dr SR Currie, Addiction Centre, Foothills Medical Centre, th St NW, Calgary, AB scurrie@ucalgary.ca Résumé : La comorbidité de la dépression majeure et des troubles liés à une substance Objectifs : Dans la population canadienne adulte, nous voulions (1) estimer la prévalence de 12 mois du trouble dépressif majeur (TDM) chez les personnes ayant un diagnostic de consommation nocive d alcool, de dépendance à l alcool et de dépendance aux drogues; (2) estimer la prévalence de 12 mois de la consommation nocive d alcool, de la dépendance à l alcool et de la dépendance aux drogues chez les personnes ayant un diagnostic de TDM de 12 mois ou de durée de vie; (3) identifier les corrélats socio-économiques de la comorbidité du trouble lié à l utilisation d une substance et de la dépression majeure; (4) déterminer comment la comorbidité influe sur la prévalence des pensées suicidaires; et (5) l utilisation des soins de santé mentale. Méthodes : Nous avons examiné les données du volet Santé mentale et bien-être de l Enquête sur la santé dans les collectivités canadiennes (ESCC, Cycle 1.2, 2002). Résultats : La prévalence de 12 mois du TDM chez les personnes souffrant d un trouble lié à l utilisation d une substance (TUS) était de 6,9 % pour la consommation nocive d alcool (intervalle de confiance [IC] 95 %, de 5,2 à 8,5), de 8,8 % pour la dépendance à l alcool (IC 95 %, de 6,6 à 11,0), et de 16,1 % pour la dépendance aux drogues (IC 95 %, de 10,3 à 21,9). À l inverse, la prévalence de 12 mois de la consommation nocive d alcool, de la dépendance à l alcool et de la dépendance aux drogues chez les personnes ayant un diagnostic de TDM de 12 mois était de 12,3 % (IC 95 %, de 9,4 à 15,2), de 5,8 % (IC 95 %, de 4,3 à 7,3), et de 3,2 % (IC 95 %, de 2,0 à 4,4), respectivement. Les modèles de régression n ont identifié aucun prédicteur socio-économique de la comorbidité TUS-TDM. La dépendance à une substance et le TDM prédisaient indépendamment une prévalence plus élevée d idées suicidaires et d utilisation des traitements de santé mentale. Conclusions : Les TUS sont très fréquemment co-occurrents dans les cas de TDM. Les cliniciens et les services de santé mentale devraient envisager une évaluation de routine des troubles liés à l utilisation d une substance chez les patients souffrant de dépression. 666