Turhan Canli
The Complexity Of Sadness

Turhan Canli likes to look at problems differently. A keen observer of the human condition, late last year he released a groundbreaking paper about depression that caused the wider science community and general public to take note. The paper recognised that we may perhaps be looking at certain mental illnesses, like depression, in the wrong way.

Having started out under the careful tutelage of eminent philosopher Dan Dennett and brain scientist John D. E. Gabrieli, Turhan Canli has been making serious waves in the scientific world for almost 15 years now. Now Associate Professor at Stony Brook University, New York, Canli has come to talk to 52 Insights about his work, and why depression is a lot more complex than you may think.

Why do you think depression is so pervasive in Western civilisation? I’ve read astonishing facts about the prevalence of the illness in our society and I get the feeling that depression has come out of the closet in the last century.

I think one way to answer that is to say that depression is not simply one thing. If we refer to the medical definition of depression it would be characterised by a long lasting period of sadness, but beyond that there are a huge number of other symptoms that any one person may or may not have. These can include changes in food intake, changes to sleep patterns, cognitive problems and so on. So it turns out that there is a very large number – up to tens of thousands  – of combinations of symptoms that mean you could call someone depressed.

Another way to think about it is to say that we really do not understand the underlying biological mechanisms associated with depression. Therefore it is hard to say whether there is anything in the environment that may have amplified those mechanisms, resulting in the rates of depression being higher now then they were at a different time.

How would you describe the human condition, following the varied work you have undertaken and studied such as emotional memory, areas of consciousness, behavioural neuroscience, genetic contributions, individual differences and polymorphism?

That’s a big question. Let me keep it closer to the science side of things. The feedback I receive comes primarily from patients and clinicians and most of the reactions – 99.99% of the reactions – I got to my recent paper were positive (see the TEDx talk below). The occasional dissent I hear comes from people who have a problem with allotting a biological explanation to depression or other mental illnesses, as if it somehow invalidates the psychological aspects of the condition.

To me the two are not mutually exclusive; to me the psychology and biology of the mind are both valid. But sometimes to understand behaviour it is telling to understand the underlying biological mechanisms. That’s one way to think about it – to think of the medical and psychological elements as intimately intertwined. People think that a treatment like talk therapy wouldn’t have a biological effect, but it does. Everything does. Every experience you have and every memory you form changes your brain; that’s what it means to be alive and to have a brain.

We usually think of ‘us’ individually as one organism, but another way to think about it is that we are really an ecosystem of organisms. There is us – the us that we know and that we are familiar with – but we are also an ecosystem, connected to millions of other microorganisms and some of them we actually need to live. For example, many intestinal bacteria are required for us to extract nutrients from our food and we could not do without them. And that’s just an example of what we know, I wonder what we do not know. There might be other microorganisms required in some way that we have not even begun to realize yet, because we haven’t looked for them. For me that is a fascinating new way to approach what it means to be human.

One of the ways in which that can become concrete is to recognise the following: our human DNA is not entirely human. Over the course of evolution viruses, in particular retro viruses, have infiltrated their hosts, including humans and our ancestors. They have a mechanism in place to insert their genetic material into our DNA so at this point in evolution it is estimated that about 8% of our DNA comes from these kinds of sources. So again, what does it mean to be human even when our DNA is not even entirely human?

A lot of your work is based around nature and how it can be mirrored in humans. It has particularly informed your work about depression. What do you think nature has yet to offer us in terms of illustrating how it could better benefit the human race?

I think it’s good advice to look at nature first. It’s had millions of years to work out what mechanisms are needed to survive. One good example of that is a study that just came out very recently about the discovery of new kinds of antibiotics. It turns out that medical treatment is currently in a very precarious state due to the fact that our antibiotics no longer work against what we know as ‘superbugs’- the bacteria that are resistant to any kind of antibacterial medication currently available. It also turns out that over the last three decades, no new medication has come to market to address the emergence of these resistant super bacteria. However, a paper has recently been released that looked at the microorganisms living in soil and delivered a whole bunch of new candidates that can be followed up on and potentially devoted to new kinds of antibacterials. That is a wonderful example of making an effort to look at nature we haven’t looked at before and being able to discover new biology that could be incredibly important and helpful to humanity.

It has been said that 10 out of the 12 major pharmaceutical companies have abandoned the field of brain research mainly due to the fact that there have been no major breakthroughs for decades. Is the circle broken in terms of scientists and pharmaceutical companies working together to help solve depression? Are the pharmaceutical companies just interested in maintaining the status quo and keeping people on their drugs?

It is true that pharmacology companies are leaving the area of brain studies, particularly the area of psychiatric illness, because it’s too hard and they are not making any real progress.

I think it indicates just how hard it is to understand psychopathology and it makes you wonder whether we need to re-conceptualize big parts of psychopathology. The way we’ve thought of it so far has apparently been fruitful enough for companies to come up with real solutions. So now we have to ask the question; is it that contemporary scientists are not good enough? Probably not. Is it that our technology is not advanced enough? Maybe, but then again we’ve had decades and made progress elsewhere.

So maybe it’s really in the way we think about psychopathology in the first place. Perhaps by conceptualizing a problem in a way that does not reflect the underlying biology we miss that underlying biology. In a sense, that is essentially what we have been trying to do with regard to talking about depression. I do not know if I am right, but at least I’m proposing something that gives clear research agenda to test whether any of what I said is right.

What’s been the response from the pharma companies to your new findings on depression

I haven’t heard anything yet.  But certainly the experience with infectious disease and the medical expertise surrounding it is significant. Just think of all the people that have gone into biomedical research studying HIV over the last three decades – that is a large talent pool of people, some of whom might decide to switch their research focus and start to look at depression.  I think that would be very exciting.

“We live in challenging times, if you look around the world, there’s reason to be depressed about a lot of things. I would not be surprised to find the way we live our lives plays a huge role in how healthy we are. ”

There still seems to be a stigma attached to depression. Would you say the work that you do could be helped if there was more awareness about the complexity of such a disease? Instead of just labeling someone as sad would it help if people really had an understanding what depression actually is?

Yes, certainly any better understanding and appreciation of the condition can only be helpful. Stigma comes from ignorance and so anything that would illuminate people about the nature of depression – psychological, biological or any way in which we can understand – can only be helpful.

Since depression is so pervasive, is there some momentum in the medical/scientific community to find a cure? Perhaps some type of scientific ‘space race’ that goes beyond prescribing Prozac?

I think there is a fair bit of discontent that we have not made more progress in the decades devoted to studying depression than we have. There is certainly a wide spread interest in academic and research circles to think of new ways to approach it. I am not sure if we are in a race as I’m not aware of anyone racing against each other. I hope momentum begins to gather pace as we ask new questions or find new approaches to study it.

Perhaps what you’re doing might change the perception of what depression is and how it is a response to the way we live. Not only viewing it as applicable to the brain but perhaps a more biological mind/body thing.

I agree, I think that is one way to think about it. Take these two examples: firstly think of a person who has faced much adversity in life, maybe early childhood trauma of some sort or perhaps chronic life problems. Some people might be resilient and not become depressed, but if someone were to become depressed you could understand why that would be.

But you may have another kind of patient who would tell you I don’t know what’s wrong with me, I have a great job, family, people who love me, I am successful and yet I feel sad. I feel empty and hopeless and I cry all the time.’ Those are very different types of experiences and the second example would be the kind of patient where I would look for a biological type of explanation. We do not necessarily need to refer to psychological processes here but at the same time, one level of explanation might be more applicable and useful to solve a problem than the other.

Could pathogens, as you have suggested, perhaps also be responsible for other diseases, not just depression?

As a matter of fact there has been some work looking at other psychopathologies, such as schizophrenia. There is a link between schizophrenia and the pathogen T.Gondi, the parasite that infects cats. It has been the subject of many studies so I think the subject of pathogens will not be limited to one psychopathology. Maybe in general it could be open to other brain disorders; we might just be scratching the tip of the iceberg.

We live in challenging times, if you look around the world, there’s reason to be depressed about a lot of things. I would not be surprised to find the way we live our lives plays a huge role in how healthy we are, physically and mentally. In fact it would be surprising if that didn’t have some kind if impact. I said earlier in my research that I am interested in gene interaction and environment, so environmental factors will always play role I am sure.

“It is estimated that about 8% of our DNA comes from these kinds of sources. So again, what does it mean to be human even when our DNA is not even entirely human?”

What’s next for you? I’d be interested to know where you’ll go from here.

I will start planning the next study with my staff. It’s going to be an exciting, small-scale study because funding is tight and it is just an exploratory one. It’s one that is designed to look for new things that are not part of the current body of knowledge, so I’m excited about that. I have no idea if it will work out but it will be fun to look. Maybe in one or two years from now I’ll be able to tell you what came of it!

TED x Turhan Canli: Is Depression an Infectious Disease?


Ian the cat - Study Buddy

This is my study buddy Ian, the world’s most famous cat. He is a medical miracle, he was diagnosed with feline leukemia when he was a kitten.  Cats usually have a few months to live from that but he’s had that diagnosis since a kitten and he’s now ten years old.


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