Bipolar disorder (BD) and substance use disorders (SUDs) frequently co-occur (1
), and people with both disorders experience worse outcomes than those having either disorder alone (4
). Despite the frequent co-occurrence of these disorders, little is known about the near-term impact of substance use itself on BD episodes. Prior research in this area has either used correlational methodology or has examined the association between SUD symptoms and BD. To our knowledge, no prior research has longitudinally examined the near-term effects of substance use
itself on BD episodes. The present study tests whether alcohol use precipitates a depressive episode among patients with co-occurring BD and SUD in the month subsequent to alcohol consumption.
A number of correlational studies have examined the relation between alcohol use and/or alcohol use disorders (AUD) and the course, treatment, and outcome of BD and other mood disorders. In a retrospective chart review of outpatients with BD, excessive alcohol use (defined as alcohol consumption causing impaired physical, social, or economic functioning) predicted hospitalization for manic symptoms during the period reviewed (7
). Furthermore, nearly twice as many patients hospitalized for manic symptoms versus depressive symptoms drank excessively. Similarly, a cross-sectional study of BD patients with alcohol use disorders found that moderate alcohol use (< 4 drinks/week for men and <2 drinks/week for women), when compared to less or no use, was associated with significantly worse outcomes in men but not women (8
). For men, higher than moderate levels of alcohol consumption were associated with a greater number of lifetime manic episodes and emergency room visits. For women, however, higher than moderate levels of alcohol consumption were associated with a shorter duration of bipolar illness and fewer depressive symptoms. Finally, a case register study demonstrated that current alcohol use increased the risk of hospitalization during the first three episodes of mood disorder, but not during subsequent episodes (9
). In sum, these correlational studies suggest that even moderate quantities of alcohol use may be associated with a more difficult course of BD, particularly early in the course of the disorder.
Other SUDs also appear be related to a more problematic course of BD. For example, one study that examined the effects of SUDs (including alcohol use disorders) in first-episode bipolar I disorder did not find significant differences in the number of weeks ill during the 2-year follow-up period between patients with a single SUD and patients without any SUD (10
). However, patients with more than one SUD had nearly twice as many weeks ill with BD as either of these other groups. Finally, in a study of patients hospitalized for a current manic episode, a history of alcohol use disorders or marijuana use disorders predicted significantly lower rates of remission during hospitalization than was seen among patients without such a history (11
To date, two studies have prospectively examined the temporal association between SUD symptoms (i.e., DSM-IV symptoms and/or Addiction Severity Index (ASI (12
)) scores) - but not necessarily substance use itself - and BD course. In a study of 50 patients experiencing a first hospitalization for BD, longer duration of AUD symptoms (i.e., DSM-IV symptoms and/or Addiction Severity Index (ASI (12
)) scores) was associated with longer duration of mood episode, particularly depression, after controlling for cannabis use disorder (CUD) symptoms during the study follow-up period of up to 24 months(13
). Furthermore, during follow-up, the amount of time spent with CUD symptoms (i.e. DSM-IV symptoms and/or ASI scores) was significantly associated with the amount of time experiencing mania. In a sub-sample of these participants who experienced changes in both AUD symptoms and a mood episode, there was no statistically significant pattern of temporal association between any SUD symptoms and mood episode. In a later study of 71 participants recruited during their first manic episode, there was no statistically significant evidence of a temporal association between AUD symptoms (i.e., DSM-IV symptoms and/or ASI scores) and BD symptoms (14
In sum, all of the preceding studies show a robust relationship between alcohol use, SUDs or SUD symptoms, and different aspects of the onset, course, and outcome of BD. However, none of these studies have examined the near-term effects of active substance use on BD episodes.
The present research seeks to build upon this prior work by examining the effects of alcohol use on the course of BD during the month subsequent to alcohol consumption. To do so, this study used a longitudinal, repeated measures design that assessed alcohol use and BD episodes prospectively among patients with co-occurring BD and SUD. Based on the research summarized above, we hypothesized that alcohol use during the current month will predict an increased likelihood of a depressive episode during the subsequent month, with alcohol use measured several ways: (1
) days of alcohol use, (2
) increased days of alcohol use from the prior month. Additionally, we hypothesized that these relationships would remain significant when controlling for current depression and other drug use. We also conducted a total of four post-hoc
analyses which examined (1
) days of heavy alcohol use (≥3 drinks/day), (2
) increased days of heavy alcohol use (≥3 drinks/day), (3
) days of non-heavy alcohol use (<3 drinks/day), and (4
) increased days of non-heavy alcohol use (<3 drinks/day).