Psychiatric problems in adolescence
As we go into our teenage years, all kinds of changes happen to our bodies and our appearance. But there are also important changes happening to our psychology too, and sometimes that can lead to mood disorders like depression. What's striking though is that girls seem to be affected twice as often as boys. But why? Well Lena Dorfschmidt, at the University of Cambridge, wondered the same thing, so she scanned the brains of a large group of adolescent children to look at which areas change their patterns of connections the most at this age. In girls there was a lot more rewiring going on, particularly in brain circuitry known to be linked to depression. This, she suspects, might make girls more susceptible to developing a mood disorder in the first place…
Lena - We know that, during adolescence, our brains develop very rapidly. We also know that, during that time, a lot of psychiatric disorders are diagnosed. For example, depression. Women are much more likely, about twice as likely, to be diagnosed with depression than men. We asked ourselves the question, "is there something about development during adolescence that may trigger this increase of incidence of depression in women during that time?"
Chris - You don't just think that there's a disparity in pickup; that women are more likely to talk about it, men are more likely to do the stiff upper lip thing and keep quiet.
Lena - There may be a certain component of that. I don't think that explains everything, though. I don't think we have women reporting symptoms twice as much as men do. Also, we have a separate sample of data where we can actually see that, even in healthy adolescents, women are more likely to experience difficulties with mood.
Chris - And you are attributing that to these very rapid changes that have to happen to the brain as we grow up?
Lena - Yeah, exactly. You can imagine this: if you wanted to reorganise your room and move things around, there's a chance you might drop something on the way. The more you change, the more likely you're going to break something. A brain is in some way similar. If you remodel or rewire a lot of connections in your brain, there's a greater chance that things may go wrong along the way.
Chris - This is the moving parts get broken more often hypothesis, isn't it?
Lena - Yeah, exactly.
Chris - So how did you try and get underneath the skin of that then?
Lena - We used MRI scanners where we can take 3D images of the brain and monitor brain activity while people are just lying in the scanner. We know that even when people don't do anything while they're lying in the scanner, we can find out a lot about the way that their brain functions already.
Chris - So, you've got groups of adolescents that you can watch in this way and ask the question, "Well, how is your brain wired up?"
Lena - Exactly. We just look at how the different brain regions communicate with each other. If neurons in specific regions fire together, we say that they're very likely to be connected, or there's connectivity between these regions. There may be two regions that are highly connected, they fire together all the time. We think that they are working together.
Chris - And how do you map that onto underlying mood or psychiatric problems?
Lena - What we did first is we looked at what this firing together of brain regions looks like in males and females separately, and then constructed a map of differences between them. We can now understand which brain regions are most different between girls and boys and men and women. What we found is there's a set of brain regions where the females develop much more drastically than the males do. So, in those regions, the women restructure, rewire much more than boys do. Then, we looked at these regions and overlapped them with the regions that we already know from other studies are implicated in depression. There's a really good match between those. We know that the same regions are impacted.
Chris - Why would a female brain wire itself into a state of depression at all?
Lena - I don't think we can say the female brain wires itself into the state of depression. The people we looked at are healthy adolescents. The only thing we are trying to show is that male and female brains develop differently and women change a bit more. It is simply that because they change more, we could assume that something may go wrong.
Chris - So, you've now got this map, or this network of connections between different regions of the brain. And you can see dynamically how that changes in adolescence. It strongly overlaps with areas that are implicated in subsequent mood disorders. Does this give us any insights into what causes that to happen? When people do get mood disorders, what we could do perhaps to head it off before they end up with an entrenched depression?
Lena - Unfortunately, we don't understand very much about that yet. There isn't a great amount of detail on how depression looks different in men and women. And this is really what we're trying to do with our work here. We're trying to show that if we want to understand how to treat depression, we need to look into males and females separately because we can now already see that there is a signal that is very different between them.