Changes in prefrontal and striatal function during reward processing are implicated in the etiology of psychosis, according to research published in JAMA Psychiatry. Researchers found an association between high psychotic-like experiences during adolescence and decreased activation in the prefrontal cortex and striatum during reward tasks, and activation in the middle frontal cortex increased over time between early and late adolescence.
This community-based cohort study sought to determine whether psychotic-like experiences in healthy adolescents could be associated with changes in prefrontal and striatal activation while processing reward tasks. Neuroimaging profiles during reward processing were evaluated to determine an association with high or low psychotic-like experiences, which were scored using the Community Assessment of Psychic Experiences Questionnaire.
The researchers evaluated 1434 adolescent volunteers for psychotic-like experiences during early and late adolescence (at age 14 and 19 year points). Only participants with either a high or low psychotic-like experience score at age 19 were included in the study, and these participants were divided into 2 groups: high (n=149) or low (n=149) psychotic-like experiences. Participants were assessed using MRI while performing a reward task involving monetary incentive delay. First-level analysis of reward processing focused on anticipation and feedback of a win; second-level analysis focused on activation of task-related regions of interest across high and low groups. The main effects of time, group, and interaction of these 2 factors on brain activation levels were examined.
The study results concentrated on 5 regions of interest within the right caudate head (9, 8, 1), right middle frontal gyrus (33, 41, 40), right middle frontal gyrus (33, 44, 31), left middle frontal gyrus (-36, 47, 31), and left cingulate gyrus (-12, -28, 40). In the right middle frontal gyrus (33, 41, 40), the effect of group/time interaction showed a significant increase in brain activation in the high psychotic-like experience group from ages 14 to 19 years (F1, 93 = 7.448; P =.01). Both the left (F1, 93 = 5.559; P =.02) and right (F1, 93 = 5.009; P =.03) middle frontal gyri showed a main effect of time on brain activation in the high psychotic-like experience group. No effects of group, time, or group/time interaction were found in the right caudate head or the left cingulate gyrus.
Limitations of the study included the selection of high and low psychotic-like experience groups based on more moderate Community Assessment of Psychic Experiences Questionnaire scores. Furthermore, because scores were not available at age 14 or the intermediate ages, the study did not track the evolution of psychosis between the 2 time points. Lack of data regarding the transition to psychosis also limits the use of the high psychotic-like experience group as a measure for ultra-high risk population.
Adolescents with high psychotic-like experiences showed an increase in right middle frontal activation during reward processing between ages 14 to 19; in addition, they demonstrated a decrease in activation of the caudate head during reward tasks at age 19. These findings indicate that developmental changes are part of the etiology of psychotic disorders, and compensatory cognitive control could be a mechanism to contextualize the psychotic-like experiences precluding psychosis during adolescence.
Papanastasiou E, Mouchlianitis E, Joyce DW, et al. Examination of the neural basis of psychoticlike experiences in adolescence during reward processing [published online August 1, 2018]. JAMA Psychiatry. doi:10.1001/jamapsychiatry.2018.1973