The impact of co-morbid alcohol use disorder in bipolar patients

Abstract

Alcohol use is highly prevalent in patients with bipolar disorder (BD) and is associated with significant mortality and morbidity. The detrimental effects of each condition are compounded by the presence of the other. The objective of this study was to examine the impact of alcohol abuse and of alcohol dependence in BD in a Brazilian sample, as indicated by clinical severity, functional impairment, and quality of life (QOL). A cross-sectional survey of 186 bipolar outpatients were interviewed using the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders—4th Edition. The primary outcome measures were functioning, as indicated by the Global Assessment of Functioning Scale scores and QOL, as indicated by the World Health Organization Quality of Life Instrument. Secondary outcomes were clinical severity features. Alcohol abuse and dependence were associated with male gender, lower education, earlier age of onset, psychosis within first episode, depressive symptoms, and worse functioning. In addition, the presence of alcohol abuse or dependence was associated with remarkably high rates of suicide attempt. Our findings suggest that the co-occurrence of alcohol abuse/dependence with BD increases the risk for suicide attempt, which may reflect in part the greater severity of symptoms and impaired functioning. This subgroup of bipolar patients requires a treatment tailored to address both conditions.

Introduction

Alcohol use is highly prevalent in patients with bipolar disorder (BD) and is associated with significant mortality and morbidity (Mitchell et al., 2007). BD is the Axis I disorder associated with the highest risk for co-existing substance use disorder (SUD) (Weiss, 2004). In turn, a study reported that 60% of the subjects who presented with alcohol problems had undiagnosed BD (McKowen et al., 2005). The Epidemiological Catchment Area Study reported a 60.7% lifetime prevalence rate for substance abuse or dependence among those with type I BD, alcohol being the most common substance abused (Regier et al., 1990). More recently, the results from the National Epidemiological Survey on alcohol and related conditions have shown significant associations between mood and drug-use disorders, and suggest that co-morbid psychiatric disorders may increase the risk of greater involvement in more serious illicit drug-use disorders (Conway et al., 2006). In clinical- and community-based samples, alcohol was also the most commonly abused substance (Brown et al., 2001, McElroy et al., 2001), and patients with type I BD had a 46% lifetime prevalence of alcohol-related disorders compared to only 14% in the general population (Brown et al., 2001). The co-occurrence of alcohol use disorders (AUD) and BD is associated with numerous negative consequences: greater risk of medication noncompliance, slower recovery from mood episodes, more frequent hospitalizations, suicides, and accidents (Goldstein & Levitt., 2008; Khalsa et al., 2008, Weiss, 2004).

BD on its own is associated with a high frequency of both suicide attempts and completed suicides, with 25–60% of patients making at least one suicide attempt during the course of their illness (Dalton et al., 2003). Likewise, alcohol consumption is a major risk factor for suicide (Nakaya et al., 2006, Sher, 2006, Sorock et al., 2006, Turecki, 2005). A prospective cohort study conducted in Japanese men indicated a significant positive association between the daily amount of alcohol consumption and suicide risk (Nakaya et al., 2006). A Diagnostic and Statistical Manual of Mental Disorders—4th Edition (DSM-IV) AXIS I diagnosis is present in about 90% of those who commit suicide (Turecki, 2005), which seems to be the cause of death in 5–15% of BD patients (Dalton et al., 2003). According to Valtonen et al. (Valtonen et al., 2006), during a medium-term follow-up, as many as one fifth of random psychiatric patients with BD attempted suicide, which highlights the public health importance of suicidal behavior in BD. Previous suicide attempts, hopelessness, and depressive phase were the key indicators of the risk (Valtonen et al., 2006). Also, SUDs rank second only to mood disorders as a risk factor for suicide attempts (Dalton et al., 2003). Patients with BD are likely to have a co-morbid diagnosis of SUD and this co-morbidity pattern appears to increase the risk of a suicide attempt up to twofold (Dalton et al., 2003). Alcohol dependence is an important risk factor for suicidal behavior, and lifetime mortality due to suicide in alcohol dependence has been reported to be as high as 18% (Sher, 2006). Individuals with alcohol dependence have a 60–120 times greater suicide risk than the nonpsychiatric population (Sher, 2006). Moreover, suicide attempters and completers have a more severe form of alcoholism compared to individuals with alcoholism who never attempted suicide (Sher, 2006).

One fact underlying the association between SUD and suicide attempts may be the severity of illness: subjects with a more severe form of BD may be more likely to both attempt suicide and use substances as self-medications (Dalton et al., 2003). In addition, the coexistence of BD and AUD may synergically contribute to impairments in functioning and quality of life (QOL), including poorer social support, a known risk factor for suicide. A history of alcohol abuse or dependence has been reported to lead to lower QOL ratings in patients with BD (Singh et al., 2005). Similarly, anxiety could be another risk factor for suicide, which is associated with both BD and AUD (Simon et al., 2004). High rates of AUD have been associated with high prevalence of anxiety disorders in those with BD (Goldstein & Levitt, 2008), consistent with the anxiolytic effects of alcohol. For instance, a study of the first 500 patients enrolled in the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) found that BD patients with lifetime anxiety disorders had roughly double the prevalence of lifetime alcohol dependence and a 50% greater prevalence of lifetime drug dependence compared to BD patients without lifetime anxiety disorders (Simon et al., 2004).

The detrimental effects of each disorder are compounded by the presence of the other (Mitchell et al., in press), and patients are more likely to relapse following treatment of their SUD if they have a co-morbid psychiatric disorder. In turn, concurrent SUD increases the chronicity, disability, and mortality rates associated with BD (Mitchell et al., in press). Accordingly, numerous case reports and surveys indicate that the use of relatively small amounts of alcohol and other drugs by those with severe mental illness adversely affects their psychiatric stability (exacerbation of illness) and psychosocial adjustment (problems of behavior, relationships, finances, and housing) (Drake & Mueser, 2000).

Despite the greater prevalence, unique pharmacological effects, and wide availability of alcohol compared to other illicit drugs of abuse, for diverse reasons, a number of previous studies in BD have combined alcohol and other substances' use disorders. In addition, many studies combine abuse and dependence in the same category, and only more recently have the different patterns of alcohol consumption in BD been examined (Goldstein et al., 2006, McKowen et al., 2005). The findings suggest that even a moderate amount of alcohol consumption could have deleterious effect in BD (Goldstein et al., 2006), and individuals with alcohol abuse, although not alcohol dependent, may have repeated legal, interpersonal, social, or occupational impairments related to alcohol consumption, frequently using alcohol in physically hazardous situations (Sher, 2006). These data are relevant to reinforce preventive strategies in clinical settings. Patients commonly give low importance to alcohol abuse, but this may be a particularly dangerous assumption in BD patients, a known vulnerable population. In fact, Castaneda et al. (1996) reviewed the potential theoretical mechanisms by which moderate alcohol use could exacerbate mood disorders, and concluded that abstinence from alcohol should be recommended for those patients.

Although this subject has been a matter of study in other countries for some decades, in South America, and specifically in Brazil, we have no knowledge of reports on the associations between BD and AUD, and of its clinical and psychosocial impact. Given the previously reported high prevalence and deleterious impact of alcohol use in the course of BD, the objective of this study was to examine the impact of alcohol abuse and of alcohol dependence in BD in a Brazilian sample; we hypothesized that BD patients who do not use alcohol would present with a better clinical course and/or outcome, associated with better functioning and QOL, and that BD patients with alcohol abuse, and those with alcohol dependence would present with worse clinical parameters, as well as lower functioning and lower self-reported QOL.