Studies about bipolar disorder have consistently found that patients tend to display either predominantly manic or predominantly depressive characteristics. This means their respective treatment options must be appropriately modified to fit the individual.
In response, Dina Popovic from the University of Barcelona and researchers from other European universities developed a pharmacological scale for measuring medications used in the treatment of bipolar disorder. This scale, called polarity index, is a relative measure of the antimanic and antidepressant efficacy of pharmaceuticals.
A quantitative tool like the polarity index can limit biases to curate more appropriate treatment plans for individuals regardless of their predominant polarity.
The polarity index can be calculated by first finding values referred to as numbers needed to treat (NNTs). NNTs are found by determining how many medication doses prevent a depressive episode, then determining how many doses prevent a manic episode. The NNT for depressive episodes is then divided by the NNT for manic episodes to find the polarity index value. To obtain these values, Popovic organized double-blind, randomized trials on medications she researched and placed participants on either a placebo or actual treatment plan for at least 24 weeks while assessing the drug’s ability to stabilize their mood. The average dose across all participants who received a certain drug was then used to find the NNT values of that medication. Using these calculations, medications that receive a polarity index value of one are said to be equally effective in preventing the onset of manic and depressive episodes, whereas values greater than one are more effective at preventing mania, and values less than one are more effective at preventing depression.
Correct usage of the polarity index provides a sustainable approach to long-term bipolar disorder treatment
Popovic’s results revealed that many drugs commonly associated with bipolar disorder treatment are much more effective at managing manic episodes than depressive episodes, uncovering a bias within the realm of bipolar disorder research. The spectrum of polarity is not given equal attention, with mania commonly seen as “more severe or problematic.” A quantitative tool like the polarity index can limit biases to curate more appropriate treatment plans for individuals regardless of their predominant polarity.
For patients with bipolar disorder, a comprehensive measurement system for approved medications means the possibility of longer maintenance treatment phases between relapsing into manic or depressive stages. Correct usage of the polarity index provides a sustainable approach to long-term bipolar disorder treatment that seeks continual prevention rather than cycling through episodes, giving insight into the lasting maintenance that remains as the final frontier of bipolar disorder treatment.
European Neuropsychopharmacology (2012). DOI: 10.1016/j.euroneuro.2011.09.008
