This one specific brain area was smaller in participants who were in love
Region is near the front of the brain and is involved in reward processing.
14 December 2016
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Poets have long described the mind-altering effects of a passionate relationship – "my love's a noble madness" wrote John Dryden. "Of all the emotions," said Cicero, "there is none more violent than love. Love is a madness." Psychology research is beginning to back this up. A recent study found that students in the early days of a passionate relationship exhibited reduced cognitive control in basic psychological tests. Now brain researchers in Japan have started to look for the neural correlates of these effects. Writing in Frontiers in Psychology, Hiroaki Kawamichi and his colleagues report the results of their brain imaging experiment showing that participants in the relatively early stages of a romantic relationship had reduced grey matter in a region of the brain involved in processing reward, which might suggest their brains had adjusted to the intensity of their love affair.
The researchers recruited 56 young men and women who were currently in a romantic relationship of at least one month's duration (the average length was 17 months), and for comparison they recruited 57 age-matched control participants who were not currently in a relationship. All the participants completed a happiness survey and also underwent a structural brain scan.
The participants in an early-stage romantic relationship were happier than those who were single. And looking across the entire brain, the researchers found one specific area – the right-dorsal striatum – that was structurally different in the in-love participants compared with the singletons, in terms of there being reduced grey matter density in the lovers. This region is found near the front of the brain, beneath the cortex and is involved in reward processing.
It's interesting that the researchers found this brain difference but without any psychological testing, or functional or connectivity-based brain scanning – which could show how brain areas speak to each other and how they operate during different mental activities – it's very difficult to interpret its meaning.
Another short-coming is that the scans were taken at just one point in time, so we've no way of knowing if being in love shrinks the right-dorsal striatum or if people with less grey matter in this area are more likely to fall in love (I'm also using terms like "in love" liberally because we don't have any detail on the intensity of the participants' romances). The only clue we have about cause and effect here is that, across all participants, the researchers found no link between striatal volume and total time in life spent in romantic relationships, suggesting a reversibility to any potential effects of romance on the brain.
Putting these important cautions to one side, it does seem plausible that enjoying a passionate romance could lead to grey matter reductions in the striatum, just as has been found in cocaine users, for example. This would make sense if you think of being in love as an intensely rewarding time, in which case the brain might "down-regulate" its reward sensitivity, adjusting to a world where there is joy to be found in each touch and embrace with, or even merely thoughts of, that special other. It might also explain why a split can be so painful – the brain spoilt by such constant reward, left craving and expectant for a comfort that's no longer there.
