By Vaughan Bell, of Mind Hacks.
To generalise, most psychiatrists see themselves as applied neuroscientists, while most clinical psychologists explain psychopathology in terms of mental processes and social relationships, and make little reference to the brain. This rift is partly fuelled by a lack of research that examines how biological and psychological factors interact to cause mental ill health. One 2005 study was a notable and refreshing exception, and has provided a compelling glimpse into how stress and the dopamine system interact to predict the presence of unusual experiences in everyday life.
Dr Inez Myin-Germeys and her team recruited 50 people who had close relatives with psychosis, as well as 50 control participants who had no family history of psychosis. Relatives of people with psychosis are more likely to have slight or fleeting psychosis-like experiences, even if they never become mentally ill themselves. This makes them an interesting and important group to study, because these experiences seem to react in a similar way to full blown psychosis, but the participants are otherwise healthy and do not take medication, both of which can muddy research findings.
The research team first gave the participants a harmless infusion of 2-deoxyglucose, a substance known to cause a temporary but measurable response in the dopamine system, to see which participants would demonstrate the most dopamine reactivity. Although the neurobiology of psychosis is complex, research has shown that dopamine function (particularly in the mesolimbic pathway of the brain) plays an important role.
Many studies that examine brain function and psychosis take place in the lab, which can make it difficult to generalise the results to everyday life. Crucially, Myin-Germeys and her colleagues used a technique called ‘experience sampling’ where participants are given a watch that beeps randomly throughout the day. When the alarm sounded, the participants were asked to note their current situation, rate their levels of stress and rate the intensity of any psychosis-like experiences.
The results showed that for the relatives, those with the most reactive dopamine systems had unusual experiences (such as hearing voices or feeling unreal) in response to everyday stresses. In contrast, stress wasn’t linked to unusual experiences in any of the other participants. In other words, the presence of psychotic experiences could only be accounted for by examining a combination of genetic risk, dopamine reactivity and stress in everyday life.
This is an important finding in itself but the study has deeper implications. One of the most heated debates in science concerns whether psychiatric conditions are mainly caused by lifelong brain dysfunction or are largely the result of stress and trauma. This study is one of a growing number that are important because they suggest that a narrow view of human distress is counter-productive, and that we need to understand both the lived experience and the biology of the brain to fully comprehend it.
Myin-Germeys, I., Marcelis, M., Krabbendam, L., Delespaul, P. & van Os, J. (2005) Subtle fluctuations in psychotic phenomena as functional states of abnormal dopamine reactivity in individuals at risk. Biological Psychiatry, 58, 105-110.
Dr. Vaughan Bell is a clinical psychologist in training, working and studying between the Institute of Psychiatry and the South London and Maudsley (SLaM) NHS Trust. He is also a researcher, interested in understanding brain injury, mental distress and psychological impairment.