Professor Tim Spector

Most of them were really low-level, what we call heritability.

And there was a massive study in Sweden.

They looked at several million sibling pairs and looked at all their mental health or brain diseases, I prefer to call them.

And there was no gene that really came out, even in several million people, that explained these diseases, other than a general tendency...

To get any type of brain disease.

So they called this factor P. If you had this general susceptibility, you could get any disease, but that could be mania, depression, bipolar, ADHD.

It could be Alzheimer's.

It could be schizophrenia.

which suddenly changes your whole view of these diseases.

We've said these are individual disease that should always be looked at separately.

And if you start thinking of this as the brain as an organ, just like anything else, like it was the liver, it's okay.

We talk about liver disease, you know, how do you prevent liver disease?

We never talk about that in brain disease.

We just say, OK, you've got to talk about manic depression differently to ADHD or personality disorder or epilepsy or whatever it is.

But it turns out that not only have the similar genes, but really similar risk factors as well.

Yeah, that's a great example of how my view of these diseases is changing.

There's really good epidemiology data now.

What's epidemiology data?

Epidemiology data is data in large populations.

So you study the cause of disease by studying populations.