True love lasts a lifetime as demonstrated by fMRI (bleh!)

Seriously, when I read the headlines to this article, I wanted to wretch retch. (Ed. I need to learn how to spell.)

Scientists discover true love

Scientists: True love can last a lifetime

I can feel it welling up now...eh...OK, I feel better.

Just to be clear, I didn't want to wretch retch because I am a deeply cynical person who scoffs at the notion of true love. (That is true, but not why I wanted to wretch retch.) I wanted to wretch retch because scientific research like this inevitably results in the worst kind of popular tripe when communicated in journalism. We are talking the most shameful, smaltzy fluff pieces -- complete with pictures of swans and anecdotal references to the journalist's own marriage.

So, what I am going to do now is save you from all of that. (You can thank me later.) We are going to have a serious discussion of this article complete with criticism. There is serious science to be discussed, and -- by Jove -- I mean to do it without personal allusion or description appropriate only for a Valentine's Day card.

Times Online reports on research by Arthur Aron et al. at Stony Brook doing imaging on couples that had been in love for 20 years or more:

A team from Stony Brook University in New York scanned the brains of couples who had been together for 20 years and compared them with those of new lovers. They found that about one in 10 of the mature couples exhibited the same chemical reactions when shown photographs of their loved ones as people commonly do in the early stages of a relationship.

Previous research suggested that the first stages of romantic love, a rollercoaster ride of mood swings and obsessions that psychologists call limerence, start to fade within 15 months. After 10 years the chemical tide has ebbed away.

The scans of some of the long-term couples, however, revealed that elements of limerence mature, enabling them to enjoy what a new report calls "intensive companionship and sexual liveliness".

The researchers nicknamed the couples "swans" because they have similar mental "love maps" to animals that mate for life such as swans, voles and grey foxes.

The reactions of the swans to pictures of their beloved were identified on MRI brain scans as a burst of pleasure-producing dopamine more commonly seen in couples who are gripped in the first flush of lust.

"The findings go against the traditional view of romance - that it drops off sharply in the first decade - but we are sure it's real," said Arthur Aron, a psychologist at Stony Brook.

Previous research had laid out the "fracture points" in relationships as 12-15 months, three years and the infamous seven-year itch.

Aron said when he first interviewed people claiming they were still in love after an average of 21 years he thought they were fooling themselves: "But this is what the brain scans tell us and people can't fake that." (Emphasis mine.)

(I have not been able to find the actual paper, presumably because it is still on embargo. Here is an earlier paper by them that sets out some of the same arguments.)

Basically, the study looked at the brain activation associated with thinking of your lover in people who had been married for long periods. The authors previous work had shown that areas in the brain associated with reward -- the ventral tegmental area (VTA) and the parts of the caudate nucleus -- are activated when young (dating less than a year) lovers think about their loved one. The authors wanted to see in those individuals who claimed to be in love after 20 years would have the same activation as the young couples.

Now the observation that romantic love activates the reward system in humans is not particularly shocking. Finding and keeping a mate is frankly a massive hassle, and the maintenance of even successful relationships often requires a degree of continuing insanity. Add to this the whole "propagation of the species" thing being selected in evolution, and it is not surprising that you would find your mate rewarding. Further, there is considerable evidence that the same reward system activated by drugs is also activated by naturally rewarding stimuli such as food, sex, and social interaction (read this review). (Note that utilizing the same reward system does not necessarily make these natural rewards "like drugs." For more information about that argument read this.)

So I don't dispute the finding that thinking of your one and only activates your reward system, and I don't find it odd that some people in love after 20 years would also have this activation.

What I take issue with is the interpretation that such activation is symbolic of "true love," as it were a read-out for the person's feelings. There are several scientific reasons why would should be skeptical of such an interpretation:

1) I have repeated this time and time again. The brain does not contain anatomical mood rings whose activation provides some read-out of positive reward. This includes the VTA. Evidence from imaging shows that VTA activity "responds to the presence of rewards, regardless of value." Thus, any statement saying that the magnitude of activation in VTA is related to how much you love someone is nonsense. I am not certain that this is the argument that they are making in their newest paper; they may merely be arguing that similar activated structures suggest similar feelings -- a sort of on/off argument. However, an allusion to degree of activation equaling degree of love should be disregarded out of hand.

2) Presumably, they did not follow these subjects over the past 20 years of their relationships. I say presumably because (correct me if I'm wrong) I don't think that functional MRI existed 20 years ago, and if it did it's use wasn't that prevalent. So this study constitutes a comparative study of a group that has been in love for a while and those that have been in love for a short time.

This poses a serious problem with controls because you have no idea what the basal level of activation was in the group of timeless lovers when their relationships were new. Maybe their activation was just gigantic at the beginning of their relationship and has slowly declined to average activation over the course of 20 years. This would explain its persistence over the period of the relationship. But you can't know that because this wasn't a longitudinal study. The comparison between two sets of individuals prohibits any statement about persistent activation. It could very well be that the set of couples dating for 20 years just started to like one another, and this shows in their brains!

3) How do we interpret this activation, and more importantly does the same activation indicate that the person feels the same thing? Does the same activation mean the representation in the brain of the other person is similar? My argument is, no. It could be the same, but this is not something that an fMRI can tell you. It could totally be possible that the feeling associated with VTA activation in young lovers is affection and is something entirely different in older lovers: pride, respect and (if you are cynical) even loathing. All that is required is that these feelings be represented in the same set of structures activated in the young lovers.

Thus, the fMRI does not provide sufficient resolution to provide insight into what the person feels. It merely indicates that the same structures are activated.

4) How exactly are they screening these older lovers? It is really difficult to tell from the article. Did they take a lot of older lovers, and find that 10% showed this activation? Did they screen out the ones who weren't in love with behavioral questionnaires, and only image the ones that were? Did they compare both groups? I think it is the last, but I want to know whether their questionnaire was accurate in distinguishing between the activated and unactivated groups.

What I shudder to consider is that they consider activation suggestive of true love and that their questionnaire failed to distinguished between the two groups. That view is certainly suggested by Dr. Aron's statement at the end above. If that is so, then they are basically saying that this activation equals true love, and whatever you other couples are feeling...well, it isn't love. That is just wrong. What the other couples are feeling may be love of a different sort or it may be nothing. But fMRI machines are not mind-readers. They are not equipped to render judgment on the validity of people's love. (As an aside, I have an almost House-esque distrust of people's statements on these questionnaires, so I would really like to see them go to these people houses and see how they interact with one another. That would let figure out whether they are in love.)

I guess my take home from all of these criticisms is not to dispute the finding that activation in the reward system associated with romantic love persists in some couples. What I dispute is how to interpret that activation. I don't think that it means that you feel the same about the person as you did when you were first dating. That might be true, but you can't know that from this experiment.

Let me make a plausible counter-interpretation: true love over many years is an evolving feeling that changes from being smitten to genuine respect and understanding. Recollection of that evolution makes us feel a perceptual warmth that activates reward centers in the brain, but the fact that being smitten and respecting someone both activate the same reward pathways is incidental. It does not indicate that the feelings are the same as the beginning of the relationship, and it is not a marker for whether that relationship will succeed.

Oh, and by the way, once I was dating this woman...(just kidding)