The Neurobiology of Falling in Love

falling in love

Falling in love is the most overwhelming of all affective states, it typically involves emotional, cognitive, behavioral and erotic components. The functions of romantic love appear not to be limited to generate offsprings, but also to promote in individuals a stable emotional environment as well as to arise pleasant and safe feelings of happiness and sex arousal, as easy as it may sound some people still have trouble getting to know someone, sometimes these people would buy today online tips on how to approach the opposite sex.

The process of romantic love in humans begins with falling in love, a subjective experience characterized by intense focused attention on a preferred individual, obsessive thinking about him or her, emotional dependency on and craving for emotional union with this beloved, euphoria and increased energy

Researchers think that falling in love is a basic emotion like anxiety or fear. When falling in love the same brain structures as in anxiety are stimulated: the amygdala and related circuits and neurotransmittors. Human beings are anxious until the bond with the loved one is accomplished. Anxiety is than replaced by positive feelings of stability and pleasure. The euphoria and focused attention when falling in love is explained by involvement of the reward and motivation systems in the human brain.

The neurochemical and hormonal basis of falling in love:

  • Reduced functionality of the serotonin transporter
  • Cortisol levels are significantly higher amongst those subjects who have recently fallen in love, this suggests the stressful and arousing condition associated with falling in love
  • FSH and testosterone levels are lower in men in love, while women of the same group presented higher testosterone levels. The opposite directions of the testosterone levels in men and women have not yet been clarified
  • Nerve growth factor, one of the key regulators of synaptic plasticity and neural survival during development and at adulthood and also increasingly recognized as potential mediator of anxiety, emotions and behavioral modifications, is significantly elevated compared to subjects with long lasting relationship and with subjects without a relationship. There was also a significant positive correlation between levels of NGF and the intensity of romantic love as assessed with the passionate love scale
  • Other regulators of synaptic plasticity and neural survival during development and at adulthood and also increasingly recognized as potential mediator of anxiety, emotions and behavioral modifications such as neurotrophins 3 and 4 and brain derived neurotrophic factor were not significantly diferent from those in love and subjects with a long lasting relationship and subjects being alone

In conclusion the neurobiological substrate of falling in love not only involves activation of the hypothalamic pituitary adrenal (HPA) axis and increase of cortisol levels. Also central neuropeptides such as vasopressine and oxytocin may play a role in the regulation of the HPA axis when falling in love. Since recent peripheral levels of neurotrophins have been investigated when falling in love but only the nerve growth factor is significantly elevated. This last factor is also connected with cortisol and the other central neuropeptides. The authors of this last research speculate that:

NGF could play a role in the molecular mechanisms of human romantic love by acting as a fine modulator of distinct endocrine functions. Alternatively, another possibility to explain our results may be that NGF plasma concentrations in subjects in love would be raised secondarily in a stress-dependent manner.

All the hormone and neuropeptide concentrations mentioned in the list are reversible in the sense that these hormones and neuropeptides revers to normal levels.

This finding would suggest that the hormonal changes which we observed are reversible, state-dependent and probably related to some physical and/or psychological features typically associated with falling in love.
Loving, T., Crockett, E., & Paxson, A. (2009). Passionate love and relationship thinkers: Experimental evidence for acute cortisol elevations in women Psychoneuroendocrinology DOI: 10.1016/j.psyneuen.2009.01.010

MARAZZITI, D. (2004). Hormonal changes when falling in love Psychoneuroendocrinology, 29 (7), 931-936 DOI: 10.1016/j.psyneuen.2003.08.006

EMANUELE, E., POLITI, P., BIANCHI, M., MINORETTI, P., BERTONA, M., & GEROLDI, D. (2006). Raised plasma nerve growth factor levels associated with early-stage romantic love Psychoneuroendocrinology, 31 (3), 288-294 DOI: 10.1016/j.psyneuen.2005.09.002