Neuroscience Suggest Three Distinct Systems for Love

Helen Fisher, an evolutionary biologist from Rutgers University, hypothesized that there are three distinct yet intersecting brain systems that correspond to sex, romantic love, and long-term attachment (like a mother-child bond or the comfortable relationship you might see in a couple who have been married for sixty years). These three separate systems, she argued, could cover all facets of love: romantic, parental, filial, platonic, and that old bugger, lust.

Scientists have long known that the seat of the sex drive is the hypothalamus. When it is removed, folks lose all interest in sex, as well as the ability to perform sexually. This almond-size brain area is linked to the pituitary gland, which produces the hormones necessary to fuel the desire to “get it on.” Humans are more than just their sex drives, however. With romantic love, Fisher and her colleagues observed brain activity in areas outside the hypothalamus, including the right ventral tegmental area (VTA) and the right caudate nucleus. These are both part of the basal ganglia, a brain area connected to both the cerebral cortex and the brain stem. The basal ganglia, along with the hypothalamus and amygdala, is implicated in reward processing and learning. It’s a little like bribery: when we experience something that feels good, such as satiating our hunger, having a sexy romp, or spending time with the object of our affections, these areas of the brain give us a little extra boost to encourage us to do it again. If we are talking about deep emotional attachment, the ventral pallidum, a different part of the basal ganglia circuitry, is activated. All these areas are very sensitive to the neurochemicals dopamine, oxytocin, and vasopressin, which are thought to be pleasure-inducing and critical to forming pair-bonds in socially monogamous animals like prairie voles and Titi monkeys. But they each work a little differently.

The two regions that seemed most important to romantic love in Fisher’s research were the caudate nucleus and the VTA. These areas reside in what is called the “reptilian brain”—a cluster of subcortical regions near the brain stem that have existed since before we evolved to walk upright—and are strongly implicated in both reward processing and euphoric feelings. They are also part of an important dopamine-fueled circuit called the mesocortical limbic system, a pathway critical to motivational systems; unsurprisingly it’s a circuit that has been implicated in addiction. These study results led Fisher and her colleauges Arthur Aron, and Lucy Brown to conclude that romantic love is not an emotion, but a drive. According to Brown,“Love is there to help fuel reproduction, to help us psychologically by connecting with others. It is distinct, yet related to lust and attachment.”

Think of it this way: Lust may be the simplest of the three hypothesized systems, an almost reflex-like process that keeps us getting busy. Certainly if it were a more involved process, we would not find ourselves so interested in individuals like Pamela Anderson in all her glory or, like one of my girlfriends who is too embarrassed to be named, totally hot for the ’s resident Lothario, Mike “The Situation” Sorrentino, right? At the same time we also have a system for attachment. Feeling connected to someone is a rewarding behavior, hence that ventral pallidum activation; it is nice to have someone to come home to, even if you are no longer inclined to jump his or her bones 24/7. Somewhere in the middle is the romantic love system, connected to both lust and attachment. It hits on areas involved in attachment and lust, as well as those implicated in reward processing and learning. It is no surprise that romantic love feels good and helps us to bond with another person (and consequently promotes procreation).

“These brain systems often work together, but I think it’s fair to say they often don’t work together too,” Fisher told me when I asked whether these three systems overlapped in other ways. “One might feel deep attachment for one partner, be in romantic love with another partner, and then be sexually attracted to many others. There’s overlap, but like a kaleidoscope, the patterns are different.”

It is also possible that these systems work on a bit of a continuum: one’s physical attraction for a person can develop over time into romantic love and then into a deep-seated attachment. It might even work the other way: a good friend to whom you are deeply attached may one day, inexplicably, seem physically irresistible. A quick flick of the wrist, a change in circumstance or age, and that love kaleidoscope may offer you a completely different configuration.

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Docs more likely to suspect abuse in poor kids

NEW YORK (Reuters Health) - When a toddler has a broken bone, pediatricians may be more likely to suspect abuse if the family is lower-income, a new study finds.

Researchers found that pediatricians who read a fictional case report of a toddler with a leg fracture were more likely to suspect abuse if the child was described as coming from a lower-income family.

The hypothetical child's race, on the other hand, did not appear to influence doctors' opinions.

The second finding is somewhat surprising, according to the researchers. Studies looking at real-world cases have found that minority children are more likely to be evaluated for abuse than white children are.

And it's well known that the child welfare system in the U.S. has a disproportionate number of minority kids.

"There's very strong evidence of a racial difference in how patients are handled," said lead researcher Dr. Antoinette L. Laskey, a pediatrician at the Indiana University School of Medicine in Indianapolis.

But, she told Reuters Health, the reasons for that have not been clear -- including whether doctors may act based on unconscious racial stereotypes.

The current results suggest "there's more than race involved," Laskey said.

She was also quick to say, however, that the study doesn't mean pediatricians are consciously "classist" or otherwise biased when evaluating children's injuries.

The study, reported in the Journal of Pediatrics, included 2,100 U.S. pediatricians who responded to a survey that described one of four hypothetical cases.

All cases included an 18-month-old with an "ambiguous" leg fracture -- a type that can be caused by abuse or an accident.

But the cases varied by the child's race (black or white) and the family's economic situation; parents were described as having either professional jobs (accountant and bank manager) or working-class jobs (grocery clerk and factory worker).

Race had little effect on the doctors' responses. The study found that when the child was black, 45 percent of doctors believed there had "possibly" or "almost certainly" been abuse; another 32 percent were "unsure." If the child was white, 46 percent of pediatricians suspected abuse, with 28 percent saying they were unsure.

In contrast, there was evidence that parents' job descriptions swayed doctors' opinions.

When the child's family was lower-income, 48 percent of pediatricians thought there'd been abuse, versus 43 percent when the family was higher-income.

It's hard to know whether doctors' responses to a fictional case would be the same in real life.

And it's not clear, according to Laskey, whether attitudes about socioeconomic status might explain some of the racial differences in child abuse reporting seen in earlier studies.

She also stressed that she does not think pediatricians are consciously basing their diagnoses on parents' job titles. But in general, unconscious stereotypes can influence anyone's thinking.

"People tend to think that child abuse, or domestic violence, doesn't happen in upper-middle-class families, but of course it does," Laskey said.

It's important, she said, for doctors to be aware that unconscious generalizations could get in the way of diagnosing child abuse -- either missing it in kids from affluent families, or over-diagnosing it in children from poorer or minority families.

"My big take-home message for doctors is that we need to rely on the objective data," Laskey said.

It is true that studies have found children in poorer families to be at greater risk of abuse. But the poverty, itself, is not a "causative factor," Laskey said.

"Race and socioeconomic status shouldn't be things used in a diagnosis of abuse," she said.

SOURCE: http://bit.ly/wVlYrX Journal of Pediatrics, online.

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Plant compounds tied to fewer heart deaths

NEW YORK (Reuters Health) - Older adults who get a moderate amount of certain plant compounds in their diets are less likely to die of heart disease or stroke, a large study finds.

The research, on nearly 100,000 older U.S. adults, found that those getting the most flavonoids in their diets were less likely to die of heart disease or stroke over the next seven years than those who ate the least flavonoids.

The compounds are found in a range of plant foods, including many fruits (like berries, citrus and apples) and vegetables (like kale, spinach and broccoli), nuts, soy, dark chocolate, tea and wine.

Research shows that flavonoids have a number of benefits, including fighting inflammation and acting as antioxidants -- which means they help protect body cells from damage that may lead to chronic diseases and cancer.

In the current study, the researchers divided participants into five groups according to the amount of flavonoids in their diets.

The one-fifth with the highest flavonoid intake were 18 percent less likely to die of heart problems or stroke than the fifth with the lowest intake.

That difference is "modest, but still relevant," said lead researcher Marjorie L. McCullough, of the American Cancer Society in Atlanta.

Given that heart disease and stroke are so common, even a modest risk reduction can make a big difference on the population level, McCullough noted in an interview.

It's not clear that flavonoids, themselves, actually lowered people's cardiovascular risks.

But flavonoid-rich foods are the types of foods we should be eating anyway, McCullough pointed out. "This provides further support for getting more of those foods in your diet," she said.

The findings, reported in the American Journal of Clinical Nutrition, are based on more than 98,000 men and women who filled out questionnaires on diet, lifestyle and medical history. At the time, they were about 70 years old, on average.

Over the next seven years, 2,771 people died of heart disease or stroke. That included 615 deaths in the fifth with the lowest flavonoid intake at the outset, and 515 deaths in the fifth with the highest intake.

When McCullough's team accounted for other factors -- like smoking, exercise habits and weight -- people getting the most flavonoids had an 18 percent lower risk of dying from cardiovascular trouble.

Flavonoid-rich foods also contain many other healthful nutrients, McCullough said. So it's hard to know whether the compounds, themselves, deserve the credit for the lower cardiovascular risks.

For example, another recent study linked magnesium-rich foods, which include nuts and dark leafy greens that are also high in flavonoids, to lowered stroke risk. (See Reuters Health story of January 13, 2012.)

The bottom line is that getting more plant foods in your diet may make a difference in your health and longevity, according to McCullough.

And these findings suggest it may not take a huge diet change, she said.

The people with the highest flavonoid intake in the study averaged about 20 servings of fruits and 24 servings of vegetables per week. The lowest-intake group got about 11 servings of fruit and 18 servings of vegetables per week.

Lower risks were also seen among older adults whose flavonoid intake fell in between the highest and lowest groups, however.

"So even adding one serving of flavonoid-rich food a day could be beneficial," McCullough said.

In general, experts recommend getting plenty of fruits and vegetables for the good of your overall health. The "DASH" diet recommended for lowering blood pressure and protecting your heart suggests four to five servings of fruit and the same number of vegetable servings each day.

A half cup of cooked vegetables or a medium-sized piece of fresh fruit would be examples of a serving.

One caveat, McCullough said, is to be careful not to douse your flavonoid-rich foods in sugar, fat or salt. "Try to keep them close to their natural form," she said.

SOURCE: http://bit.ly/A9uZ9D American Journal of Clinical Nutrition, online.

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