8 January 2019
Examination of the Neural Basis of Psychotic-like Experiences in Adolescence During Reward Processing
We caught up with Dr Evangelos Papanastasiou to discuss his latest publication, and the next steps for improving the early diagnosis of psychotic illness.
Can you tell us more about yourself?
I am a psychiatrist with a special interest in the link between cognition and schizophrenia. I recently completed my PhD in Psychosis Studies at the Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, as a member of the Cognition Schizophrenia and Imaging Laboratory (CSI lab).
The CSI lab, headed by Professor Sukhi Shergill, specialises in studying cognition in various presentations of the psychosis spectrum, by employing state-of-the-art assessments and neuroimaging techniques.
What is the rationale behind your study?
Occasional psychotic-like experiences are relatively common in healthy adults and adolescents, but when these experiences become highly frequent this can indicate the beginning of a psychotic illness. Late adolescence is a critical time for the onset of psychotic illness, as this is when psychotic symptoms typically begin to manifest.
Which methods did you use?
To investigate long-term changes in brain activation, 298 healthy adolescents underwent functional magnetic resonance imaging, whilst performing a reward processing task, at the age of 14 years old and again at 19 years old.
Neurocognitive measures were obtained by employing the CANTAB battery, specifically the Affective Go/No-go Task, to complement our neuroimaging findings.
What were your key findings?
Interestingly, adolescents with a higher frequency of psychotic-like experiences at age 14 showed reduced brain activation in three prefrontal areas of the brain during the reward processing task.
However, by the age of 19 these adolescents showed both increases in the activation of the prefrontal regions and a decrease in the activation of a region in the dorsal striatum, during the same task, compared to adolescents without psychotic-like experiences.
This finding suggests a compensatory cognitive control mechanism where ‘higher’ prefrontal cortical areas are recruited in order to contextualize abnormal experiences generated by ‘lower’ subcortical areas.
What are the implications of your study?
Our findings are consistent with the neurodevelopmental model of psychosis, which advocates that abnormal brain development from early childhood through adolescence to adulthood can be linked to the development of psychosis. An improved understanding of these compensatory changes during adolescence would be very helpful in developing strategies to reduce the transition to illness.
What are the next steps for your research area?
Biological markers (biomarkers) accompanied by psychotic-like experiences, such as the ones discovered in this study, may prove useful for improving early diagnosis of psychotic illness.
Currently there are no biomarkers for psychosis, but in the future there is hope to combine data from patient interviews, neuroimaging studies, and possibly genetic testing to increase the accuracy of predictive diagnoses.
Evangelos Papanastasiou MD MSc PhD