Emotional immune systems

03 December 2019

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Question

Is there a connection between the immune system and emotion?

Answer

Immunologist Clare Bryant answers...

Clare -  Yes, it's a really interesting emerging area. So, if you look at patients that have got severe depression, for example, what you find is, if you look in blood samples from these patients, they actually have elevated levels of inflammatory mediators. And in fact, you can look at different mouse models of depression and you can see that in those animals, you get the influx of immune cells into the brain, you can see increase in inflammatory mediators, and there seems to be a gathering body of evidence to suggest that. And it kind of makes sense because stressed people will produce cortisol. Cortisol dampens the immune system. So you can see how the immune system and the CNS works in balance. And also immune cells can actually modify regions of neurons called synapses, which is where neurons talk to each other. Immune cells can actually trim little areas of this off. So, you could see how there's a complex interplay between the immune cells and the neurons and that would then affect mood and mood disorders.

Chris -  And is that the basis of the observation that if you take, say an elderly person caring for another elderly person who describes that as very stressful or someone who is lonely and you find that in them, they tend to respond much less well to say a flu vaccine?

Clare - Presumably, yes. I mean, it all will kind of make a lot of sense, wouldn't it? That these kinds of interplays between efficiency of vaccination and what's happening within your brain and your mood would potentially affect how your immune system responds. But also in the elderly, we know that they are already in a state of heightened inflammation anyway, and that could also affect how a vaccine works. So I think it's, it's a very complex interplay of different systems.

Chris - And can that affect the progression of heart disease, James, and how fast arteries fur up, cause there's an inflammation part and parcel of that.

James - Very much so, Chris. Yeah, inflammation has long been recognized as probably the prime player, really, all the way along from very early vascular disease, very early hardening of the arteries, all the way through to triggering heart attacks. And hence stat in drugs. Probably half of the effect that they have is due to their anti inflammatory effect on the arteries.

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