Can bipolar disorder be considered a malfunction of the "love circuit" in the human brain? I've not so long ago read a book on depression by a Russian psychiatrist Vladimir Levi. The book's title can be roughly translated as "Not only depression, but a pursuit of mood". I have not been able to find an english translation, so I cannot quote it directly.

In that book, the author lists several examples of love-related depression, where a person who drops out of a love relationship experiences symptoms of moderate to severe depression. 

This got me thinking - love is often portrayed as the "ultimate goal" in religion, popular culture, movies, etc. The psychiatrist above provides examples that losing love can result in depression. Another condition that is characterized by dramatic uplift in mood and outlook on life is the hypomania stage of Bipolar Disorder. Bipolar disorder is characterized by multiple episodes of hypomania/mania and depression over the course of a lifetime.

Putting both phenomena together, it appears to me that there are similarities, and I'd like to ask these questions:

-Does bipolar disorder use the same mechanisms/pathways in the brain that "love" does?

-If so, can bipolar disorder be considered a malfunction of the "love circuit" in the human brain?

UPDATE: I found this article on neurochemistry of loVe on Wikipedia 


  Chemically, the serotonin effects of being infatuated have a similar
  chemical appearance to obsessive-compulsive disorder; which could
  explain why people experiencing infatuation cannot think of anyone
  else.[12] For this reason some, such as anthropologist Helen Fisher,
  assert that taking SSRIs and other antidepressants impede one's
  ability to fall in love.


From the article on love:


  Studies in neuroscience have involved chemicals that are present in
  the brain and might be involved when people experience love. These
  chemicals include: nerve growth factor,[8] testosterone, estrogen,
  dopamine, norepinephrine, serotonin, oxytocin, and vasopressin.[9


From the Wikipedia article on bipolar disorder causes


  A review seeking to identify the more consistent findings suggested
  several genes related to serotonin (SLC6A4 and TPH2), dopamine
  (DRD4 and SLC6A3), glutamate (DAOA and DTNBP1), and cell growth
  and/or maintenance pathways (NRG1, DISC1 and BDNF), although noting
  a high risk of false positives in the published literature.
A Love Circuit?

The idea that there is a "love circuit" has little evidence (for or against it). But in general studies that look at "love" (however defined) reveal broad activation across multiple intrinsic neural networks that are involved in many different cognitive processes (in favor of a constructivist view of emotions). 

Consider the image from a meta-analysis (Cacioppo et al., 2012) of functional imaging studies on sexual desire and love:



Both sexual desire and love are associated with greater activation of the insula, hypothalamus, ventral striatum, VTA, amygdala, thalamus, hippocampus, anterior cingulate, and other limbic/cortical areas.  These regions are involved in interoception, memory, conceptualization, core affect, somatosensory integration, motivation, salience detection, and more.  

Note, however, that these areas are not specific to love; instead, they are involved in emotional experience more broadly (fear, disgust, anger, happiness, etc.; Touroutoglou, Lindquist, Dickerson, &amp; Barrett, 2015). It's still possible that the above pattern of activation is unique to love; however, this has not been tested (to my knowledge)--nor does it seem plausible in light of other evidence (i.e., Touroutoglou et al., 2015).

Because these brain areas are involved in many cognitive processes, we might imagine that dysfunction in at least some of them is associated with bipolar disorder. 

Bipolar Disorder

Consider the image below from a meta-analysis (Chen, Suckling, Lennox, Ooi, &amp; Bullmore, 2011) of functional imaging in bipolar patients:



Compared to healthy controls, bipolar disorder seems to be associated with decreased inferior frontal gyrus activation in response to cognitive or emotional tasks and increased limbic activity (amygdala, hippocampus, parahippocampal gyrus, basal ganglia) in response to emotional tasks.

Conclusion

As you can see, there is some overlap with the areas activated for love/sexual desire and bipolar disorder (e.g., limbic structures).  

However, this is not compelling evidence that BD somehow involves dysfunction in a "love circuit," as the limbic system is involved in all emotions, not just love. If anything, this suggests that BD is associated with dysfunction in emotion regulation/processing/reactivity (and executive function more broadly; Robinson et al., 2006).