Biology of romantic love

Academics have proposed a number of theories for how addictions are created and maintained.<ref name=":27">{{Cite journal |last=Robinson |first=Terry E. |author-link=Terry Earl Robinson |last2=Berridge |first2=Kent C. |author-link2=Kent C. Berridge |date=2025-01-17 |title=The Incentive-Sensitization Theory of Addiction 30 Years On |url=https://www.annualreviews.org/content/journals/10.1146/annurev-psych-011624-024031 |journal=Annual Review of Psychology |language=en |volume=76 |pages=29–58 |doi=10.1146/annurev-psych-011624-024031 |issn=0066-4308 |pmc=11773642}}</ref> One prominent theory developed by [[Wolfram Schultz]] involves a dopamine signal which encodes a reward prediction error (RPE), the difference between the ''predicted'' value of a reward which would be received by performing a particular action and the ''actual'' value upon receiving it (i.e. whether the reward was better or worse than expected). In this view, dopamine is part of a mechanism for [[reinforcement]] learning (and a form of [[classical conditioning]]) which associates rewards with the cues which predicted them. Drugs of abuse like [[cocaine]] hijack this mechanism by overstimulating dopamine neurons, mimicking an RPE signal which is much stronger than could be produced naturally.<ref>{{Cite journal |last=Schultz |first=Wolfram |author-link=Wolfram Schultz |date=2016-03-31 |title=Dopamine reward prediction error coding |url=https://doi.org/10.31887/DCNS.2016.18.1/wschultz |journal=Dialogues in Clinical Neuroscience |volume=18 |issue=1 |pages=23–32 |doi=10.31887/DCNS.2016.18.1/wschultz |pmid=27069377}}</ref> An alternative model developed by [[Kent C. Berridge|Kent Berridge]] and [[Terry Earl Robinson|Terry Robinson]] states that dopamine signaling causes the motivational output (incentive salience) which is proportional to RPE, but that the dopamine signal itself may only be an effect of that learning rather than causing it directly.<ref name=":28">{{Cite journal |last=Berridge |first=Kent C. |date=2007-04-01 |title=The debate over dopamine’s role in reward: the case for incentive salience |url=https://doi.org/10.1007/s00213-006-0578-x |journal=Psychopharmacology |language=en |volume=191 |issue=3 |pages=391–431 |doi=10.1007/s00213-006-0578-x |issn=1432-2072}}</ref><ref name=":10" /><ref name=":27" /> The computation of dopamine signaling is complicated, with inputs from many areas of the brain, although its output (primarily from the VTA) is a relatively homogeneous signal encoding the level of RPE.<ref>{{Cite journal |last=Watabe-Uchida |first=Mitsuko |last2=Eshel |first2=Neir |last3=Uchida |first3=Naoshige |date=2017-07-25 |title=Neural Circuitry of Reward Prediction Error |url=https://www.annualreviews.org/content/journals/10.1146/annurev-neuro-072116-031109 |journal=Annual Review of Neuroscience |language=en |volume=40 |pages=373–394 |doi=10.1146/annurev-neuro-072116-031109 |issn=0147-006X |pmc=6721851}}</ref><ref>{{Cite journal |last=Diederen |first=Kelly M. J. |last2=Fletcher |first2=Paul C. |date=2021 |title=Dopamine, Prediction Error and Beyond |url=https://journals.sagepub.com/doi/10.1177/1073858420907591 |journal=The Neuroscientist |language=en |volume=27 |issue=1 |pages=30–46 |doi=10.1177/1073858420907591 |issn=1073-8584 |pmc=7804370}}</ref> One study has investigated whether people in long-term romantic relationships experienced RPE in response to having expectations about their partners' appraisal of them validated or violated, indicating they do. This study used fMRI to find that reward areas like the VTA and striatum responded in a way consistent with other research on RPE.<ref>{{Cite journal |last=Poore |first=Joshua |last2=Pfeifer |first2=Jennifer |last3=Berkman |first3=Elliot |last4=Inagaki |first4=Tristen |last5=Welborn |first5=Benjamin Locke |last6=Lieberman |first6=Matthew |date=2012-08-08 |title=Prediction-error in the context of real social relationships modulates reward system activity |url=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2012.00218/full |journal=Frontiers in Human Neuroscience |language=English |volume=6 |doi=10.3389/fnhum.2012.00218 |issn=1662-5161 |doi-access=free}}</ref> Most fMRI studies of romantic love have had participants look at a photograph, and the resulting dopamine activity has been interpreted in terms of salience.<ref name=":9" /><ref name="fisher2016" /><ref name=":7" />

Academics have proposed a number of theories for how addictions are created and maintained.<ref name=":27">{{Cite journal |last=Robinson |first=Terry E. |author-link=Terry Earl Robinson |last2=Berridge |first2=Kent C. |author-link2=Kent C. Berridge |date=2025-01-17 |title=The Incentive-Sensitization Theory of Addiction 30 Years On |url=https://www.annualreviews.org/content/journals/10.1146/annurev-psych-011624-024031 |journal=Annual Review of Psychology |language=en |volume=76 |pages=29–58 |doi=10.1146/annurev-psych-011624-024031 |issn=0066-4308 |pmc=11773642}}</ref> One prominent theory developed by [[Wolfram Schultz]] involves a dopamine signal which encodes a reward prediction error (RPE), the difference between the ''predicted'' value of a reward which would be received by performing a particular action and the ''actual'' value upon receiving it (i.e. whether the reward was better or worse than expected). In this view, dopamine is part of a mechanism for [[reinforcement]] learning (and a form of [[classical conditioning]]) which associates rewards with the cues which predicted them. Drugs of abuse like [[cocaine]] hijack this mechanism by overstimulating dopamine neurons, mimicking an RPE signal which is much stronger than could be produced naturally.<ref>{{Cite journal |last=Schultz |first=Wolfram |author-link=Wolfram Schultz |date=2016-03-31 |title=Dopamine reward prediction error coding |url=https://doi.org/10.31887/DCNS.2016.18.1/wschultz |journal=Dialogues in Clinical Neuroscience |volume=18 |issue=1 |pages=23–32 |doi=10.31887/DCNS.2016.18.1/wschultz |pmid=27069377}}</ref> An alternative model developed by [[Kent C. Berridge|Kent Berridge]] and [[Terry Earl Robinson|Terry Robinson]] states that dopamine signaling causes the motivational output (incentive salience) which is proportional to RPE, but that the dopamine signal itself may only be an effect of that learning rather than causing it directly.<ref name=":28">{{Cite journal |last=Berridge |first=Kent C. |date=2007-04-01 |title=The debate over dopamine’s role in reward: the case for incentive salience |url=https://doi.org/10.1007/s00213-006-0578-x |journal=Psychopharmacology |language=en |volume=191 |issue=3 |pages=391–431 |doi=10.1007/s00213-006-0578-x |issn=1432-2072}}</ref><ref name=":10" /><ref name=":27" /> The computation of dopamine signaling is complicated, with inputs from many areas of the brain, although its output (primarily from the VTA) is a relatively homogeneous signal encoding the level of RPE.<ref>{{Cite journal |last=Watabe-Uchida |first=Mitsuko |last2=Eshel |first2=Neir |last3=Uchida |first3=Naoshige |date=2017-07-25 |title=Neural Circuitry of Reward Prediction Error |url=https://www.annualreviews.org/content/journals/10.1146/annurev-neuro-072116-031109 |journal=Annual Review of Neuroscience |language=en |volume=40 |pages=373–394 |doi=10.1146/annurev-neuro-072116-031109 |issn=0147-006X |pmc=6721851}}</ref><ref>{{Cite journal |last=Diederen |first=Kelly M. J. |last2=Fletcher |first2=Paul C. |date=2021 |title=Dopamine, Prediction Error and Beyond |url=https://journals.sagepub.com/doi/10.1177/1073858420907591 |journal=The Neuroscientist |language=en |volume=27 |issue=1 |pages=30–46 |doi=10.1177/1073858420907591 |issn=1073-8584 |pmc=7804370}}</ref> One study has investigated whether people in long-term romantic relationships experienced RPE in response to having expectations about their partners' appraisal of them validated or violated, indicating they do. This study used fMRI to find that reward areas like the VTA and striatum responded in a way consistent with other research on RPE.<ref>{{Cite journal |last=Poore |first=Joshua |last2=Pfeifer |first2=Jennifer |last3=Berkman |first3=Elliot |last4=Inagaki |first4=Tristen |last5=Welborn |first5=Benjamin Locke |last6=Lieberman |first6=Matthew |date=2012-08-08 |title=Prediction-error in the context of real social relationships modulates reward system activity |url=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2012.00218/full |journal=Frontiers in Human Neuroscience |language=English |volume=6 |doi=10.3389/fnhum.2012.00218 |issn=1662-5161 |doi-access=free}}</ref> Most fMRI studies of romantic love have had participants look at a photograph, and the resulting dopamine activity has been interpreted in terms of salience.<ref name=":9" /><ref name="fisher2016" /><ref name=":7" />

Research has not investigated whether romantic love shares all of the neurobiological aspects of addiction.<ref name="bode" /><ref name=":32" /> Despite similarities, there are also differences between romantic love and addiction. One of the major differences is that the trajectories diverge, with the addictive aspects tending to disappear over time during a relationship in romantic love. By comparison, in a drug addiction, the detrimental aspects magnify over time with repeated drug use, turning into compulsions, a loss of control and a negative emotional state. It has been speculated that the difference between these could be related to oxytocin activity present in romantic love, but not in addiction.<ref name=":7" /><ref name=":13" /> Academics do not universally agree on whether or not love is always an addiction or when it needs to be treated.<ref name=":32">{{Cite journal |last1=Earp |first1=Brian D. |last2=Wudarczyk |first2=Olga A. |last3=Foddy |first3=Bennett |last4=Savulescu |first4=Julian |date=2017 |title=Addicted to Love: What Is Love Addiction and When Should It Be Treated? |journal=Philosophy, Psychiatry, & Psychology |language=en |volume=24 |issue=1 |pages=77–92 |doi=10.1353/ppp.2017.0011 |issn=1086-3303 |pmc=5378292 |pmid=28381923}}</ref> The term "[[love addiction]]" has had an amorphous definition over the years and does not yet denote a [[psychiatric condition]], but recently one definition has been developed that "Individuals addicted to love tend to experience negative moods and affects when away from their partners and have the strong urge and craving to see their partner as a way of coping with stressful situations."<ref name=":14">{{Cite journal |last1=Costa |first1=Sebastiano |last2=Barberis |first2=Nadia |last3=Griffiths |first3=Mark D. |last4=Benedetto |first4=Loredana |last5=Ingrassia |first5=Massimo |date=2021-06-01 |title=The Love Addiction Inventory: Preliminary Findings of the Development Process and Psychometric Characteristics |journal=International Journal of Mental Health and Addiction |language=en |volume=19 |issue=3 |pages=651–668 |doi=10.1007/s11469-019-00097-y |issn=1557-1882 |doi-access=free}}</ref> Other authors include rejected lovers as love addicts,<ref>{{Citation |last=Bolshakova |first=Maria |title=Passionate Love Addiction: An Evolutionary Survival Mechanism That Can Go Terribly Wrong |date=2020-08-31 |work=The Cambridge Handbook of Substance and Behavioral Addictions |pages=262–270 |editor-last=Sussman |editor-first=Steve |url=https://www.cambridge.org/core/product/identifier/9781108632591%23CN-bp-20/type/book_part |access-date=2025-06-12 |edition=1 |publisher=Cambridge University Press |doi=10.1017/9781108632591.026 |isbn=978-1-108-63259-1 |last2=Fisher |first2=Helen |last3=Aubin |first3=Henri-Jean |last4=Sussman |first4=Steve|url-access=subscription }}</ref> or specify that love is an addiction when it involves abnormal processes which carry negative consequences. A broader view is that all love is addiction, or simply an [[appetite]], similar to how humans are dependent on [[food]].<ref name=":32" /> Research on behavioral addictions is more limited than research on drugs of abuse, but there is a growing body of evidence that some people are susceptible and show brain patterns similar to drug addicts, particularly in the case of [[gambling addiction]].<ref name=":28" /><ref>{{Cite web |last=Bellamy |first=Tom |date=10 July 2025 |title=Addicted to Addiction |url=https://www.psychologytoday.com/gb/blog/everyday-neuroscience/202507/addicted-to-addiction |access-date=2025-07-14 |website=[[Psychology Today]] |language=en-GB}}</ref> [[Helen Fisher (anthropologist)|Helen Fisher]], [[Arthur Aron]] and colleagues have proposed that romantic love is a "positive addiction" (i.e. not harmful) when requited and a "negative addiction" when unrequited or inappropriate.<ref name="fisher2016" />

Research has not investigated whether romantic love shares all of the neurobiological aspects of addiction.<ref name="bode" /><ref name=":32" /> Despite similarities, there are also differences between romantic love and addiction. One of the major differences is that the trajectories diverge, with the addictive aspects tending to disappear over time during a relationship in romantic love. By comparison, in a drug addiction, the detrimental aspects magnify over time with repeated drug use, turning into compulsions, a loss of control and a negative emotional state. It has been speculated that the difference between these could be related to [[oxytocin]] activity present in romantic love, but not in addiction.<ref name=":7" /><ref name=":13" /> Academics do not universally agree on whether or not love is always an addiction or when it needs to be treated.<ref name=":32">{{Cite journal |last1=Earp |first1=Brian D. |last2=Wudarczyk |first2=Olga A. |last3=Foddy |first3=Bennett |last4=Savulescu |first4=Julian |date=2017 |title=Addicted to Love: What Is Love Addiction and When Should It Be Treated? |journal=Philosophy, Psychiatry, & Psychology |language=en |volume=24 |issue=1 |pages=77–92 |doi=10.1353/ppp.2017.0011 |issn=1086-3303 |pmc=5378292 |pmid=28381923}}</ref> The term "[[love addiction]]" has had an amorphous definition over the years and does not yet denote a [[psychiatric condition]], but recently one definition has been developed that "Individuals addicted to love tend to experience negative moods and affects when away from their partners and have the strong urge and craving to see their partner as a way of coping with stressful situations."<ref name=":14">{{Cite journal |last1=Costa |first1=Sebastiano |last2=Barberis |first2=Nadia |last3=Griffiths |first3=Mark D. |last4=Benedetto |first4=Loredana |last5=Ingrassia |first5=Massimo |date=2021-06-01 |title=The Love Addiction Inventory: Preliminary Findings of the Development Process and Psychometric Characteristics |journal=International Journal of Mental Health and Addiction |language=en |volume=19 |issue=3 |pages=651–668 |doi=10.1007/s11469-019-00097-y |issn=1557-1882 |doi-access=free}}</ref> Other authors include rejected lovers as love addicts,<ref>{{Citation |last=Bolshakova |first=Maria |title=Passionate Love Addiction: An Evolutionary Survival Mechanism That Can Go Terribly Wrong |date=2020-08-31 |work=The Cambridge Handbook of Substance and Behavioral Addictions |pages=262–270 |editor-last=Sussman |editor-first=Steve |url=https://www.cambridge.org/core/product/identifier/9781108632591%23CN-bp-20/type/book_part |access-date=2025-06-12 |edition=1 |publisher=Cambridge University Press |doi=10.1017/9781108632591.026 |isbn=978-1-108-63259-1 |last2=Fisher |first2=Helen |last3=Aubin |first3=Henri-Jean |last4=Sussman |first4=Steve|url-access=subscription }}</ref> or specify that love is an addiction when it involves abnormal processes which carry negative consequences. A broader view is that all love is addiction, or simply an [[appetite]], similar to how humans are dependent on [[food]].<ref name=":32" /> Research on behavioral addictions is more limited than research on drugs of abuse, but there is a growing body of evidence that some people are susceptible and show brain patterns similar to drug addicts, particularly in the case of [[gambling addiction]].<ref name=":28" /><ref>{{Cite web |last=Bellamy |first=Tom |date=10 July 2025 |title=Addicted to Addiction |url=https://www.psychologytoday.com/gb/blog/everyday-neuroscience/202507/addicted-to-addiction |access-date=2025-07-14 |website=[[Psychology Today]] |language=en-GB}}</ref> [[Helen Fisher (anthropologist)|Helen Fisher]], [[Arthur Aron]] and colleagues have proposed that romantic love is a "positive addiction" (i.e. not harmful) when requited and a "negative addiction" when unrequited or inappropriate.<ref name="fisher2016" />

In brain scans of long-term intense romantic love (involving subjects who professed to be "madly" in love, but were together with their partner 10 years or more), attraction similar to early-stage romantic love was associated with dopamine reward center activity ("wanting"), but long-term [[Attachment theory|attachment]] was associated with the [[Globus pallidus|globus palludus]], a site for [[Opioid|opiate]] receptors identified as a hedonic hotspot ("liking"). Long-term romantic lovers also showed lower levels of obsession compared to those in the early stage.<ref name=":4" /><ref name=":02" />

In brain scans of long-term intense romantic love (involving subjects who professed to be "madly" in love, but were together with their partner 10 years or more), attraction similar to early-stage romantic love was associated with dopamine reward center activity ("wanting"), but long-term [[Attachment theory|attachment]] was associated with the [[Globus pallidus|globus palludus]], a site for [[Opioid|opiate]] receptors identified as a hedonic hotspot ("liking"). Long-term romantic lovers also showed lower levels of obsession compared to those in the early stage.<ref name=":4" /><ref name=":02" />