Bipolar II disorder compared to bipolar I disorder – the results are not what you would expect

Based on the following article: “American tertiary clinic-referred bipolar II disorder compared to bipolar I disorder: More severe in multiple ways, but less severe in a few other ways” Dell’Osso, B et.al. Journal of Affective Disorders 188 (2015) pp. 257-262. http://dx.doi.ord/10.1016/j.jad2015.09.001

A common misconception that is prevalent under people and even doctors is that bipolar I disorder (BD-I) is worse than bipolar II disorder (BD-II). This is mainly based on the fact that, by definition hypomania is a less severe mood elevation than mania. Let us then look at the difference in the DSM criteria for the two types of BD. To be diagnosed with BD-I you have to have experienced mania (one episode is enough) and the presence of depressive episodes are not required whereas in the case of BD-II, less severe mood elevation episodes (hypomania) and major depressive episodes need to be present.

The difference between hypomania and mania cannot be simplified to hypomania just being less severe than mania. Mania is more destructive since it can entail psychosis, hospitilization and severe functional impairment. It is therefore understandable that people would think BD-I is worse than BD-II. This reasoning is however flawed in the sense that BD is not only characterized by hypomania and mania, but by other factors as well. In the study I am discussing here, the authors have looked at the prevalence of a long list of illness characteristics.

The characteristics can be divided into three groups:

1. Characteristic more prevalent in BD-II than in BD-I
2. Characteristic more prevalent in BD-I than in BD-II
3. Characteristic not significantly different in prevalence between BD-I and BD-II

The following characteristics fall under group 1:

• Anxiety disorder
• Currently depressed
• Currently taking an antidepressant
• Rapid cycling
• More than 10 episodes
• First degree relative disorder
• Childhood onset
• Not on any medication
• Personality disorder

The characteristics in group 2 are:

• Prior psychosis
• Prior hospitalization

The characteristics in group 3 are:

• Prior suicide attempts
• Alcohol/substance abuse disorder
• Eating disorder

Figure 1 and 2 summarize the abovementioned findings. The findings in figure 1 were more consistent with other studies and those in figure 2 is less consistently reported in prior studies.

As is seen in the analysis, the amount of BD-II patients not taking medication is double the amount of BD-I patients taking medication. However when the data was restricted to only medicated patients similar trends were observed. From the data on first degree relative with a mood disorder as well as childhood onset and an earlier onset age, it can be deduced that the genetic component is more robust in BD-II than BD-I.

As is evidenced here BD-II can be more severe in multiple ways and should not just be shrugged off as the “lighter” version of BD-I. Due to its high association with unfavourable illness characteristics, high rates of delayed diagnosis, and slower commencement of treatment together with poor response to treatment can make BD-II particularly challenging.

If there is one lesson to be taken from this analysis it is that BD-I and BD-II are clinically different and therefore it is very important to develop treatment plans specific to each type of BD and not just use the same formula for everyone suffering from BD. From a personal point of view I would also add that BD-I’s and BD-II’s should have respect for each other. I want to go further than this study and say that each case of BD-I or BD-II is different from the next, therefore you should never compare yourself with someone else suffering from BD, even if it is the same type! My message: respect and understanding is key to the BD community uniting to form a unified group, irrespective of differences in type and perceived severity amongst individuals.