00:00What they were really doing was exploring a question which is why do most mental health
00:07issues like depression, psychosis, bipolar disorder, start in adolescence?
00:14What's the explanation for it?
00:15And over the last few years, there's been increasing interest in the role of the immune
00:20system in the brain.
00:21So there are immune cells in the brain and the immune system affects how the brain works.
00:28And the question is, could this be cause and effect?
00:31So in other words, I mean, it could be nothing whatsoever to do with mental health issues,
00:36but could the immune system have a role?
00:37And it's been increasingly believed that it does.
00:40And therefore, where do these problems in the immune system in the brain come from?
00:47And this study is a study that started in the early 90s in Britain, following parents
00:53and babies through the years, looking at all sorts of aspects of their health and
00:58development through the years.
01:01And they particularly looked at something called inflammation.
01:04And inflammation is when the immune system is turned on.
01:08So something's going wrong, don't know what it is, it could be an infection or it could
01:12be something else, and we'll come back to that in a minute.
01:14And it's been turned on, and it's like an artillery barrage.
01:18So it's nonspecific, it's just the immune system flares up and gets angry.
01:24And there are blood tests you can do to measure, in a sense, how angry the immune system is.
01:30And they did three of these tests at the age of nine, age of 15, and age of 17, and looked
01:36at whether or not these kids had mental health issues or metabolic issues like leading to
01:40diabetes at the age of 24.
01:43And what they showed was that kids whose inflammation levels peaked at age nine, in
01:50other words, they were high at age nine, then tailed off a bit, those were the ones who
01:55were at increased risk, up to five times the risk of depression, severe depression, psychosis,
02:02and indeed metabolic problems, at the age of 24.
02:06Now there are various things that could turn it on, infection, but they eliminated infection
02:11as one of the causes of this.
02:16Polluted air increases inflammation because it's like smoking, if I'm particular air pollution.
02:21But also it's noticed that chronic stress from the environment, either in the family
02:26or in the surrounding area of where the child's growing up, is that a child under stress,
02:33the brain picks that up as a threat and turns on the immune system, and inflammation turns
02:40on not because of an infection, but because the world around the child is threatening
02:46in a sort of subtle kind of way.
02:50So this could be the link between, we know that environmental issues in children do increase
02:56the risk of mental health issues, and this could be the explanation.
03:01Environmental health issues, social and physical, stimulation of the immune system, and that
03:07having an effect on the brain producing mental health.
03:09It does seem that if the inflammation peaks later in life, at 15 or 17, they're not at
03:16the same risk.
03:17So yeah, this is something that happens in a child's early years and maybe primary school
03:22years, if indeed it's real.
03:24But there's other evidence to suggest this is a real effect.
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