Considerable work has explored the psychosocial impact of major depressive disorder and bipolar I disorder, yet few studies have looked at psychosocial impairment in bipolar II disorder. Given the growing interest in the “soft” spectrum, more attention to the burden associated with these disorders is needed. Indeed, there is some evidence to suggest that major depressive episodes, more common in bipolar II disorder, lead to greater impairment than hypomanic or manic episodes (MacQueen et al., 2000
The present study compared psychosocial functioning associated with bipolar II disorder to the functioning seen in the more widely studied conditions of bipolar I and major depressive disorder. We were careful to take into account the possibility that impairment measures may have been confounded with current or lifetime depression.
Several findings emerged. First, the three conditions had different effects on work functioning. Second, we found that both bipolar disorders were associated with greater hospitalizations than depression alone. Third, both bipolar I and II disorder were associated with a greater number of serious suicide attempts than major depressive disorder. Finally, we found similar levels of social functioning across the conditions. Overall, the psychosocial impact associated with bipolar II disorder was much more similar than it was different from the impact associated with bipolar I disorder. There was no indication from the current results that bipolar I and II differed with respect to the impact of depression. Rather, when differences existed between the two conditions, they could be accounted for by the higher rate of hospitalization in the bipolar I group.
Before discussing implications from these findings, several limitations deserve mention. Our sampling was not random. Rather, all participants were outpatients seeking treatment; therefore, these results may not generalize to other types of psychiatric practices (e.g., inpatient settings). We also can not rule out the possibility that the impairment associated with bipolar II disorder may be due to a selection bias, given that more seriously ill bipolar II patients are more likely to go into treatment.
Our design was cross sectional, making our models of causation tentative. Indeed, our findings remain associations between bipolar disorders and psychosocial consequences rather than predictive models. It is not definite that bipolar disorders lead to more work impairment; the opposite, though unlikely, may be the case. The causal relationship between hospitalizations, age of illness onset and work impairment is similarly uncertain. When we controlled for number of hospitalizations, the bipolar I and II groups did not differ from each other. However, hospitalizations may simply reflect the disorder’s severity, so a model that controls for it before comparing work impairment across the two groups may be inappropriate. Similarly, we cannot rule out the possibility that a third variable, not measured in our study and not inherent to the bipolar diagnosis, was the cause of more serious impairment in the bipolar groups. We did not have a healthy, non-psychiatric control group. This limitation is mitigated in part by studies that have already shown that bipolar I and major depressive disorder lead to impairment.
One final potential limitation of the current work involves our method of diagnosing groups. We made diagnoses based on DSM-IV criteria and using the SCID. While a widely used assessment instrument, serious concerns exist regarding the validity of DSM-IV criteria for hypomania as well as the validity of the SCID to diagnose these conditions (Akiskal & Benazzi, 2005
). Specifically, the 4-day criteria for hypomania may not be empirically supported; moreover, the SCID’s reliance on a mood skip-out may lead to misdiagnosis. The relevance for the current study from these potential problems is that many participants in the MDD group may in fact have belonged to the bipolar spectrum. Depending on the level of impairment among these possibly misdiagnosed participants, it could have made the bipolar II group appear more or less impaired. Future work needs to carefully consider that subgroups of MDD patients may in fact belong to the bipolar spectrum by assessing hypomanic episodes lasting less than 4 days, that are antidepressants-induced, and by considering alternative assessment methods (cf. Akiskal & Benazzi, 2005
One of the primary findings from the present study was the high toll on work functioning associated with bipolar II disorder. One third of people with the condition had missed over a year of work in the last five years due to the illness. The average amount of time patients with bipolar II disorder were not working due to their illness in the last 5 years was between 6 months and a year. These rates fall between the amount of time out of work associated with bipolar I disorder and that associated with major depressive disorder. Although there was more absenteeism in patients with bipolar I disorder, the difference appeared to be related entirely to them having been hospitalized more frequently. The work losses faced by patients with bipolar II disorder are substantial, particularly since our measure of absenteeism was conservative and may represent an underestimate: it only counted days missed if it was specifically due to psychopathology (rather than medical illness) and only in those patients who were expected to work (i.e., excluded students, retired people, etc.). A central message from the present study, therefore, is that even “soft” bipolar disorders, specifically bipolar II disorder, lead to major impairment in people’s ability to work.
In contrast to work functioning, we found no evidence that the disorders were associated with differences in social functioning. The small non-significant differences that exist suggest that even a larger sample size with more power would still fail to find a major difference. Why the disorders lead to differences in work but not social functioning is unclear. It may be that our measure of social functioning was not sensitive enough to detect smaller gradations in functioning. Alternatively, it may simply be that work functioning is far less resilient to the effects of a mood disorder than social skills and social bonds. Indeed, over 60% of all three groups reported “good” functioning or better in the last 5 years. An example anchor for this level of social functioning was “1 or 2 special friends that he saw from time to time and was fairly close to.” The lack of a healthy control group makes it hard to ascertain whether all groups had moderate social functioning or whether all groups equally suffered in their social functioning from the effects of each disorder.
Bipolar II disorder was also associated with high rates of hospitalization and high rates of suicide attempt. Over 40% of the bipolar II group had been hospitalized at least once compared to only 26% of the major depressive disorder group. This was still less than the bipolar I group (over 70% had been hospitalized at least once). Perhaps most troubling, bipolar II disorder, similar to bipolar I disorder, was associated with a high rate of past serious suicide attempts. The rate of attempts in bipolar II disorder (27%) was almost as high as in bipolar I disorder (33%). Moreover, these rates reflect serious suicide attempts (i.e. attempts with a high risk for death) rather than merely suicidal gestures that might not be lethal (e.g., self-harm gestures). This result underscores a major conclusion from the present work, namely, that it would be a mistake for clinicians to presume that bipolar II disorder involves less serious consequences compared to bipolar I disorder. It also confirms that bipolar I and II disorder are more impairing than major depressive disorder alone.