Falling in Love – Nature’s Trick or a Temporary insanity? by Dr Mark Taylor
Mark Taylor, MD; FRANZCP, FRCPE, FRCPsych
Introduction
It’s perhaps no surprise that the genius of Shakespeare, who personally introduced 1700 new English words to the language and himself used approximately 64 thousand words, compared to the average person’s 35 thousand, set the quintessential love story “Romeo and Juliet” in Verona, Italy.
Here I summarise a chapter by Italian psychiatrists Mazzariti et al, from the University of Pisa, called “The Science of Love: State of the Art” from a book on Nerve Growth Factor and other peptides, published in 2021.
A question implied in this book chapter, assuming that love is a real phenomenon, is whether ‘falling in love’ is Nature’s Trick to subtly facilitate procreation and the survival of the species, or whether the state of ‘love’ is simply an ephemeral variant of hypomania and thus a form of temporary insanity.
The Science
Mazzariti et al postulate that ‘love’ has several stages, with early romantic love arising during a specific maturational period and being linked with activation of the limbic system and associated decreased serotonin and altered monoamines. The evolutionary purpose of this is to narrow down mating to one or a few promising partners leading to a sense of safety, accompanied by emotional and sexual reward, with enhanced fertility.
Mazzariti et al then note that the phase of romantic love lasts between six months and two years, which is approximately the time required for successful mating, delivery, and care of a newborn child.
This state of love is said to be independent from sexual attraction; bonding; or the feeling of being reciprocated and is described as involving pleasure, safety, and completeness in a pair-bonding. Nature, it is conjectured, provides this complex biological mechanism to facilitate mating within a wider group-structure or social organisation.
Attraction according to Mazzariti et al is a basic emotion, like fear and anxiety, sometimes being blind to preconception. The thalamus processes the incoming ‘attractive’ stimuli, sending signals to the amygdala directly as well as the cortex. The amygdala organises an emotional response, with chemical sequelae, preparing the individual for flight or fight via the activated cortex. However, the clever cortex recognises this as an atypical flight or fight response, and thus ‘love’ becomes fear without fear. The authors claim that this shared biology is evident across cultures, validating its biological necessity.
The state of romantic love can lead to an elevation in mood and intrusive thoughts resembling clinical hypomania, with disturbances in sleep and appetite, along with altered judgement. This ‘hypomanic’ state has the benefits of lowering inhibitions, overcoming fear and neophobia, despite the attendant catecholamine-related anxiety.
Increased nerve growth factor and brain-derived neurotrophic factor (BDNF) have been documented in romantic lovers (Emanuele et al, 2006) suggesting a biological advantage to this state. BDNF may be induced by oestrogen and thus more active in women, during this altered mental state, reflecting a biological imperative to procreate.
Oxytocin, sometimes referred to as the ‘cuddle chemical’ or the ‘love hormone’, is well recognised as being involved in pair bonding and infant-maternal attachment, whilst the related peptide vasopressin has opposing properties. Both are produced in the hypothalamus and released by the posterior pituitary, possibly systemically via ‘the smart vagus’ nerve, leading to some of the bodily changes experienced during ‘love’. Oxytocin produced in the ‘attraction phase’ reduces the anxiety and fear response, and this reduced stress is thought to be accompanied by dopamine mediated reward-activation. Functional MRI scans showed activation of the oxytocin-rich areas of the brain when subjects were asked to view photos of their romantic partners.
Functional MRI neuroimaging has also revealed that subjects who are ‘in love’ during testing (compared to those who were ‘never in love’) demonstrate greater activity in the left anterior cingulate (known to be an emotion processing part of the cortex) and increased connectivity in the reward network of the basal ganglia and nucleus accumbens, as well as increased activity in the social cognition network of the temporoparietal and posterior cingulate regions.
There is a downside to this increased neural activity during romantic love, according to Mazzariti et al, with love (and the loss of love) leading to “a greater risk of developing a full-blown psychiatric disorder”. Other authors such as Insel and Fisher et al have likened the state of love to an addiction, with dopaminergic reward systems giving reinforcement when the romantic dyad is positive, but after rejection a negative withdrawal or mood rebound can occur. Shakespeare and these Italian psychiatrists might have had this in mind…
Conclusions
Mazzariti et al state that the purpose of this scientific research is ‘not to destroy the poetry of love’ but to facilitate a deeper understanding of our neurobiology and unique humanity. Interestingly, they also say that this understanding may “prevent the suffering and dramatic consequences of unrequited love and separations,” unconsciously alluding to one of the main themes in Romeo and Juliet.
From this preliminary evidence, it does seem that genuine neurochemical changes occur in ‘the state of love’. How this is similar or different to a state of clinical hypomania remains to be seen.
Professor Mark Taylor,
BSc (Hons); MD; FRANZCP; FRCPsych; FRCP
References
- Donatella Mazzariti, Stefania Palermo, and Federico Mucci. (2021) The Science of Love: state of the art. Chapter 16 in Recent Advances in NGF and related molecules, Springer, vol 1331. https://doi.org/10.1007/978-3-030-74046-7
- 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.