Could the Size of the Brain Predict Bipolar Disorder?

Posted on October 1, 2012 by

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Let’s say you wanted to find a biological indication of your bipolar disorder, or your husband’s, or your child’s.

You’d have good reason for looking for one.

Biological markers could ,in theory, clarify the diagnosis (no more, ‘she’s just a drug abuser,’ or ‘maybe he’s just got an irregular depression’), might actually find out what phase the patient is in (this seems less useful to me–don’t most people know the difference between a manic and depressive state?), and (and here’s a winner) maybe even determine if treatments are working. While it’s hard for the patient to tell at times if her medication is actually pulling its weight, an objective graph with, say, fewer peaks in the waves, could clearly indicate a more effective treatment.

So you’re sold–and you’d like to have a biological indicator to utilize for diagnostic, assessment and treatment purposes. Well, we don’t have one that will do all those things, I’m sorry. It would sure be nice.

What we might have is a marker that could help indicate who’s susceptible to bipolar disorder in advance.

How do you go about finding a biomarker of bipolar?

Up to now, there has been one way to get it–and it isn’t pleasant.

The only biological indicators of bipolar disorder available to us are those collected post-mortem–and a fat lot of good that does to someone suffering right now.

But times they are ‘a-changing.

According o  lead scientist was Tomas Hajek, M.D., Ph.D., an associate professor of psychiatry at Dalhousie University in Halifax, Canada, in his publication in the July 23rd issue of Biological Psychiatry researchers may just have discovered a potential biomarker for bipolar.

Studying 154 subjects–19 adolescents or young adults with bipolar disorder, 50 relatives of people with bipolar disorder but no signs of the illness, 36 relatives who also had the illness and 49 control subjects, the research team used MRI imaging and discovered that those with bipolar disorder–and all relatives, affected or unaffected by the illness, had a larger inferior frontal gyrus (which is just a fancy name for the frontal lobe, involved in emotional regulation and socio-emotional learning) in the brain than control subjects.

 

Thus it may very well be that an abnormally large inferior  frontal gyrus is, in fact, a biomarker for bipolar disorder. As Hajek at al conclude, in ever-so-academic prose, in the article with the witty and winning title, “Brain Structural Signature of Familial Predisposition for Bipolar Disorder: Replicable Evidence For Involvement of the Right Inferior Frontal Gyrus,” “the rIFG volume could aid in identification of subjects at risk for BD even before any behavioral manifestations.”

Globes (2)

The plot thickens, as the findings were the opposite of what might have been expected. Generally, abnormally small–not large–brain structures are associated with mental illness, yet here we have quite the opposite.

Hajek himself admitted surprise at his findings, but the results were consistent and replicated.

In an ideal world, such structural imaging could be used to identify people before the disorder arises–and alleviate stressors that might cause trouble.

We’re still a ways from that yet, though.

The first chink in the armor is that scientists don’t even know if an enlarged inferior frontal gyrus is correlated only with bipolar, or if, in fact, it’s symptomatic of all mental illness. Figuring that out might be a good place to start before worrying about early identification.

Additionally, while those early in the course of the illness do indeed have that large frontal gyrus, those who’ve been bipolar longer have–ready for this?–an abnormally small inferior frontal gyrus.

So what happens? And why? And how does it relate to the course of the illness–and to treatment?

I couldn’t tell you–and it doesn’t look like anyone else can at this point, either. But an indicator that might help identify who’s at risk for developing bipolar disorder is something well worth pursuing.

And maybe one day, when I’m old and gray–or older and grayer–we’ll have biomarkers for whether treatments actually work or not. In the meantime, it’s still the world of trial and error–and mood charting.