Computational phenotype and disposition to psychopathology: Delay discounting in young people

Michael Moutoussis
University College London

There are good reasons to suppose that psychiatric disorders are underpinned, at least in part, by 
distortions in decision-making. We sought to relate variations in psychopathological symptoms to 
decision-making processes in a community sample of young people. Here we focus on the relationship 
of conduct problems with metrics of delay discounting, a key neuroeconomic metric related to 
impulsivity. Here I will present information from a study of decision-making in young people. We 
assessed inter-temporal discounting preferences of a representative population sample of 650 14-24 
year olds living in Cambridgeshire or London. We inferred underlying computational parameters using 
both established and novel models. Key parameters derived from these models were used as predictors 
of self-reported dispositions, psychiatric symptoms taking account also of IQ, socioeconomic indices and 
age. We found that modelling the data was more successful if choice variability in discounting tasks was 
under stood as preference uncertainty in participants. Higher temporal discounting correlated with 
increased conduct problems, lower IQ and socioeconomic disadvantage. Discounting parameters varied 
little with age and did not appreciably mediate the association of IQ or other psychopathology with 
conduct problems.There is much scope for interpretation of this data and suggestions for further 
research. Certainly discounting plays an important, albeit non-specific, part in the relation between 
decision-making and psychiatric vulnerability in adolescence. We suggest that high discounting and 
decision variability may reflect a cognitive pattern of reduced confidence in thinking ahead, based both 
on lower ability (e.g. IQ) and in learning about unpredictable environments (e.g. socioeconomic 
disadvantage), in turn conferring vulnerability. Further characterisation of the developmental trajectory 
and biological representation of cognitive parameters can contribute to a deeper understanding of core 
vulnerability factors for the emergence of psychiatric symptoms.