Is the serotonergic system altered in romantic love? A literature review and research suggestions

Infatuated individuals think about their beloved a lot. The notions that these frequent thoughts resemble the obsessions of obsessive-compulsive disorder (OCD) patients and that those patients benefit from serotonin reuptake inhibitors (SSRIs), have led to the hypothesis that romantic love is associated with reduced central serotonin levels. In this chapter, the literature on this topic is reviewed and suggestions for future research are made. Previous studies have shown that romantic love is associated with lower blood serotonin levels and with lower serotonin transporter densities, the latter of which has also been observed in OCD patients. Further, SSRIs have been found to decrease feelings of romantic love and the serotonin 2 receptor gene has been associated with the love trait ‘mania’, which is a possessive and dependent form of love. Given that serotonin 2 receptors in the prefrontal cortex have also been implicated in impulsive aggression, this suggests that stalking behavior may be associated with these receptors. In short, the serotonergic system appears to be altered in romantic love indeed. Future research is needed to identify what parts of the serotonergic system, such as which serotonergic projections, brain areas, transmission stages and receptor types, are affected in romantic love and in what way they are altered. Furthermore, challenging the serotonergic system would be useful in determining the causal relationship between central serotonin levels and feelings of romantic love. In addition, future research should specifically investigate the different aspects of romantic love, such as state, trait, requited and unrequited love and its development in time.