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A Compelling New Theory of Depression

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A Compelling New Theory of Depression

A fascinating theory has been put forward by Turhan Canli PhD, Associate Professor of Psychology and Radiology at Stony Brook University, which could change the future direction for research and treatments of depression. 

According to Dr Canli, depression should be re-conceptualised as an infectious disease. His argument is a compelling one.

In a paper published in Biology of Mood & Anxiety Disorders, Dr Canli suggests that depression could be the result of a parasitic, bacterial or viral infection.

Depression is a pervasive illness, with around 16% of people experiencing an episode at some point in their lives.

There has been little change in treatments over the last few decades and although antidepressants are effective in reducing symptoms in patients with severe symptoms, in patients with mild to moderate symptoms they are no more clinically effective than placebos.

Recurrence of depression is common. Those who have experienced one episode have a 50% chance of recurrence. Those who have experienced depression twice have an 80% chance of experiencing it a third time.

Dr Canli explains, ‘Given this track record, I argue that it is time for an entirely different approach. Instead of conceptualising depression as an emotional disorder, I suggest to reconceptualise it as some form of an infectious disease.’

Dr Canli is also a member of the Program in Neuroscience, and a Senior Fellow in the Center for Medical Humanities, Compassionate Care, and Bioethics. ‘I propose that future research should conduct a concerted search for parasites, bacteria, or viruses that may play a causal role in the etiology of depression.

 Dr Canli presents three arguments for reconceptualising depression as an infectious disease:

  1. ‘Patients with depression experience sickness behaviour’.

    The main criteria for a diagnosis of depression are affective symptoms, specifically a loss of energy and diminished interest in the world and previously enjoyable activities. However  inflammatory biomarkers of depression strongly suggest the origin of depression to be illness related. Dr Canli suggests that the inflammatory markers may indicate the stimulation of the immune system in response to a pathogen such as a parasite, bacterium or virus. He acknowledges that there is currently no direct evidence that depression is caused by a micro-organism, however the process is a plausible one and warrants further research.

  2. There is clear evidence that parasites, bacteria and viruses can affect emotional behavior.

    Parasites: There is evidence that infection by the parasite, T. gondii is associated with elevated inflammatory biomarkers similar to that observed in depressed patients;

    Bacteria: Research has begun to investigating the causal links between emotional behaviour and bacteria in the gut.

    Viruses: A meta-analysis of 28 studies looked at the link between depression and infectious agents. Borna disease virus (BDV) has been found to be 3.25 times more likely to be found in depressed patients than in normal controls. Further research is necessary to understand the link.

  3. The genetics of the illness.

    Genetic studies to date have looked at human genes within the human genome (complete set of DNA). However, the human body is host to other micro-organisms, with their own genetic makeup, that can be passed across generations. As a result, ‘the opportunity for genetic discoveries is vastly amplified’.

Based on these three arguments, Dr Canli suggests the future research in the area involve large-scale studies with depressed patients, controls, and infectious-disease related protocols. He explains, ‘Such efforts, if successful, would represent the ‘end of the beginning’, as any such discovery would represent the first step toward developing a vaccination for major depression.’

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12 Comments

Mandy Titterton

I think he could be right, i’ve suffered with depression all my life and have thought for some time i could have a bacterial infection or parasites

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Karen Young

His arguments make really good sense don’t they. We’re learning more about depression every day but there’s still so much to learn. It’s so good to see new research tracks opening up. Hope you’re doing okay.

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Susan

I became mentally ill at 37, at the same time I had bad acne rosacea, with lots of pustules, I have noticed that with a flare of this disease I also had major depression . So now when the flare starts i have two weeks on antibiotics and then have a treatment with Limelight strength laser to my face. This keeps it away for two years. I have also had weight gain and gut problems from the drugs I was prescribed, i know my gut flora was affected so i am also thinking there is a link to a germ. I still struggle but can manage with these measures and a sensible diet, however weight loss doesnt seem to happen easily once your body has aclimatISed to a larger weight.

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Debra Farrell

I have suffered since I was 15 years old, I have years where I am fine but it comes back. My mother and my daughter also suffer, my Daughter most off the time. It is very encouraging that research could be going in a new direction.

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heysigmund

Be assured that there is so much research happening around depression. It just affects so many people and it’s important that the research keeps moving forward so we can come up with better treatment options. Just know that it’s happening. Thank you for taking the time to make contact.

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Meg

This is particularly fascinating to me as my 15-year-old son was brought almost literally to his knees by a sudden, severe depression the week after doing his first 5K obstacle mud run which took him through countless flooded swamps and even a flooded cow pasture. The depression has barely loosened its grip and continues to flare. Because he has never once had depression or even much sadness I am thoroughly convinced there is something biological at work. Blood tests today!

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heysigmund

That is really interesting. There seems to be a lot of research happening around depression at the moment. It’s opening up different pathways but it’s also making me realise that there’s so much more to know about it. I’m pleased your getting blood tests – it sounds as though your son is in good hands. It will be really interesting to see what they reveal. It must have been awful to see such a sudden change in your son. I hope they find something that can give you both comfort. Would love to hear how you go.

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Meg

Strange to say how upset I am that his blood tests showed nothing. They did a whole CBC workup and blood counts, adrenal function and thyroid are all perfectly normal. No sign of infection. I am waiting to hear the results of Lyme’s disease and thinking of using a consult with a pediatric neurologist to look at other testing. Has anyone heard of PANDAS? It’s a strep infection that affects the ganglia/brain stem and causes mood disorders, tics, etc. It’s a stretch but worth exploring. Maybe I’m in denial? But the suddeness and severity of this has me thinking physiological illness.

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heysigmund

I completely understand why you would be upset about the bloods not showing anything. It’s just not making any sense for you is it, that’s the awful thing about this. There was a comment in the article on the Anxiety in Kids post about PANDAS. The post is on the home page – the first one in the slider up the top. It was posted on 15 March by a mother who’s been there. There’s a link there that might be helpful for you. I really don’t know enough about it to comment but I think it’s good to be open to everything. Your doctors would be the ones to talk to. It sounds as though you have a good team there who are trying everything they can to get to the bottom of it. Having said that, there’s a lot to be said for a mother’s intuition.

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