How can brain scanning help find out more about psychosis?

Professor Philip McGuire: My name is Philip McGuire, I am a professor of psychiatry at the Institute of Psychiatry in London and I am the academic lead for a group of clinicians and researchers who are working on psychosis.

One of my main research roles at the Institute of Psychiatry is to lead a team working on the use of neuroimaging, or brain scanning, to try and understand what causes psychosis. So the reason why brain scanning is potentially very useful is that it allows us to see in an individual what it happening in their brain in terms of the chemistry, or the structure, or the function of the brain, without doing any harm, and potentially before they have developed an illness.

It gives us a way of measuring in the living person the processes in the brain that are thought to underlie psychotic disorders.

There’s many different kinds of brain scanning techniques and these really use similar kinds of machines to give you different kinds of information. So, the kind that people are most familiar with is what’s called structural brain scanning – so that tells you about the structure of the brain, the neuro-anatomy of the brain – a sort of static picture of what the architecture of the brain looks like. Then there’s what’s called functional imaging, which as the name suggests, tells you not about the structure, but the activity in the brain, the function of the brain in a more dynamic way, so sometimes the anatomy of the brain may look quite normal but its function may be altered. So this kind of imaging technique allows you to look at that.

And then another kind of imaging is what’s called neurochemical imaging which allows you to look at the chemistry of the brain. And the reason that is particularly important in psychosis is that we know that psychosis involves changes in particular chemicals in the brain and many of the treatments for psychosis act on these chemical systems.

But increasingly, people are recognising the value of doing all of these in the same individual, and then you can see the big picture of how the findings all fit together. So in other words, understanding the relationship between chemical changes in the brain and structural and functional changes in the brain, because these things don’t in reality occur in isolation, they are all part of the same process.

In our imaging research, increasingly we try to use all the different techniques in the same individual when that’s possible.

In order to do neuroimaging research in psychosis, it involves both healthy individuals and people who have different forms of psychotic problems. So first of all it’s very important to study healthy people to understand what the normal processes that you are investigating look like, and because brain scanning is a relatively new area of research, a lot of the normal chemistry and function and structure of the brain is not that well understood, so it’s crucial to involve healthy individuals, so a lot of the scanning we do is in healthy people.

And then in terms of clinical subjects, they could involve any kind of patient, or perhaps not patients, but people who have psychotic-like experiences but are perhaps not formally suffering from a psychotic illness. And a lot of the brain scanning research that we do is in people in the very early stages of psychosis, and the advantage of studying people at this stage of illness is that you have the opportunity of examining the brain before the potentially confounding effects of treatment are introduced. One of the issues in research and psychosis is how do you know what you are measuring is really to do with psychosis, or is it an effect of the treatment that has been given for the disorder. So if you study people in the early stage of illness, perhaps before treatment has even started, then that is not an issue.