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Wednesday, December 21, 2011

Can a Picture Of Your Mother Diagnose Depression?

Can a Picture Of Your Mother Diagnose Depression?

Sigmund Freud gets a bad rap from modern science. (The immunologist Peter Medawar summarized the feeling of many with his remark that psychoanalysis is the “most stupendous intellectual confidence trick of the twentieth century.”) Sure, Freud’s theories mangled a lot of details — we no longer worry about penis envy or the Oedipus complex — but he was shockingly prescient on the big themes. In recent years, it’s become clear that, as Freud always insisted, the unconscious is the dominant force in our mental life. (What Freud called the id is now a network of brain areas associated with emotion, such as the amygdala and nucleus accumbens.) He was mostly right about the logic of dreams, which often regurgitate those parts of experience we store in long-term memory. And he was basically correct to imagine the mind as a set of conflicted drives, with reason competing against the urges of the passions. We expend a lot of neurotic energy holding ourselves back.

But there’s another Freudian theme that deserves a little 21st century appreciation: his obsession with the mother-child relationship and the way it shadowed people throughout life. Freud saw this parental bond as a dominant motive for behavior, influencing both our development as children and our happiness as adults. (The super-ego, for instance, begins to form when the incestuous desires of the child are thwarted by the father.) Although many of Freud’s particular claims feel like cultural relics, modern attachment theory has confirmed the crucial importance of the maternal bond. As Harry Harlow put it, “You’ve got learn how to love before you can learn how to live.” And it’s our mothers who often first teach us how to love. (Thankfully, human parenting is slowly becoming much more gender neutral. But this a recent cultural innovation.)

A new paper in PLoS ONE expands on this Freudian theme. The study involved a team of scientists at Columbia University, Beth Israel Medical Center and Albert Einstein Medical Center who performed fMRI scans on 28 female subjects between the ages of 18 and 30, half of whom were suffering from unipolar depression. (The patients were evaluated using the Beck Depression Inventory II.) While lying in the scanner, the volunteers looked at pictures of their mothers, a few friends and a selection of strangers. The scientists focused their attention on the left anterior paracingulate gyrus (aPCG), a brain area that plays an important role in the regulation of social emotion. Previous studies have linked the bit of cortex to error and conflict resolution and the understanding of intentionality.

By looking at the differential brain responses of depressed and control subjects after viewing those various faces, the scientists came up with an impressive diagnostic tool. In fact, the fMRi scans were able to predict the presence of depression in nearly 90 percent of subjects; the correlation between actual BDI scores and the predicted BDI scores based on fMRI results was 0.55, which is quite strong. Out of the 28 subjects, the fMRI diagnosis generated one false positive and two false negatives.

Here’s where Freud comes in: the neural differences were only significantly different when the young females were viewing photos of their mothers. (When looking at pictures of friends and strangers, every brain looked similar.) In the data below, notice the differential response between the activity generated by maternal faces compared to that generated by friends and strangers, as mothers generated a much larger response from the aPCG in those suffering from depression:

Obviously, there are many statistical tricks one can play on fMRI data to generate mistaken correlations; only time will tell how these results hold up. It’s also unclear what’s driving this fMRI observation. What is the aPCG up to? The scientists throw out a number of possibilities, including the disregulation of social bonding hormones like oxytocin, but these remain mostly speculation:

Oxytocinergic activity in the hypothalamus has been linked in studies of attachment to reward processing activity in the ventral striatum and is in turn regulated by the aPCG and other areas of the medial PFC. Higher activity in this area for depressed subjects during appraisal of attachment figures and others could reflect compensatory control activity in a dysregulated network, as has been suggested in various studies.

So we don’t understand why this effect exists. But we do know that it’s a pretty robust phenomenon and that people with moderate to severe depression exhibit an unusual neural response when viewing pictures of their mothers, at least when compared to pictures of friends and strangers. (Future studies should look at other family members.) Although these subjects are adults, the maternal relationship remains a window into the murk of their mental illness, as the Viennese doctor surmised long ago. This doesn’t mean our parents are responsible for our sadness — it’s too early to say if Philip Larkin was right about mum and dad — but Freud was definitely onto something when he insisted that the maternal relationship be considered in the context of therapy. When attempting to diagnose depression using the patterns of activity exhibited by the brain, it turns out that we don’t need to ask people lots of questions or measure stress levels or investigate their mood. Rather, we only need to show them a picture of their moms.

Image: Library of Congress

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