Abstract
Background
Childhood trauma (CT), a generic term encompassing experiences of severe abuse and neglect during childhood and adolescence, has been established as an important risk factor for the emergence of psychosis. Among the potential pathways involved in the CT-psychosis association, Theory of Mind (ToM) disruption holds a central position. ToM reflects the ability to attribute distinct mental states to oneself and other people, and correctly infer the beliefs, wishes, intentions and dispositions of others in order to predict their behavior and produce proper social responses. ToM is further elaborated in 1st order ToM (ToM1: the ability to understand that someone may hold a false belief about the state of the world) and 2nd order ToM (ToM2: the ability to understand that one person may hold a false belief about the belief of another person). Research shows that patients with schizophrenia-spectrum psychosis (SSP) exhibit marked deficits in ToM. CT may increase SSP risk by disrupting the emergence of normal ToM skills, thus inducing a vulnerability for cognitive errors, perceptual aberrations and impaired reality testing. Our study sought to explore the effect of CT on ToM performance in a group of SSP patients and a healthy control group (HC).
Methods
We compared 63 SSP patients to a healthy control group on measures of CT and ToM. CT (presence of parental antipathy, parental neglect, physical abuse, sexual abuse) was assessed with the Childhood Experience of Care and Abuse Questionnaire (CECA.Q). ToM1 and ToM2 performance was measured with the Perception of Social Inference Test (PESIT). Chi-squared analysis was performed to compare CT rates between SSP patients and HCs. Mann-Whitney U tests were employed to detect differences in ToM between the two groups. Within each group, the impact of CT and polytraumatization (accumulation of different CT types) on ToM performance was examined.
Results
SSP patients displayed significantly higher CT rates (χ2 (1, N = 124) = 34.5, p < .001) and worse ToM performance (ToM1: U = 653,5, p < .001; ToM2: U = 435,5, p < .001) than HCs. SSP inpatients were 11.6 times more likely to have been exposed to severe CT than HCs. Within the SSP group, CT was associated with increased ToM2 deficits (U = 259, p = .020), while polytraumatization was negatively correlated to both ToM1 (rs = -.297, p = .020) and ToM2 (rs = -.341, p = .007) performance. Maternal antipathy (U = 207, p = .036) and neglect (U = 148, p = .017) were the CT subtypes associated with worse ToM2 performance. No similar effects were detected within the HC group.
Discussion
Our finding of ToM deficits in SSP patients may indicate a bidirectional association, involving on the one hand a negative effect of psychotic illness on ToM skills, and on the other hand a vulnerability towards psychosis induced by severe, early disruptions in normal ToM acquisition. Worse ToM performance in SSP patients with cumulative CT may signify an additive or synergistic effect of CT and psychosis on ToM skills. The involvement of maternal antipathy and neglect in the aforementioned association highlights the pivotal role of the mother in the development of the child’s capacity to envision distinct mental states in self and others, a prerequisite for self-awareness and self-other individuation. The failure to detect similar effects in HCs may be attributed to the low frequency of CT in this group, potentially restricting the strength of this analysis. On the same matter, another explanation could be that CT by itself is not a sufficient condition for ToM impairment, and only becomes relevant when it acts in synergy with other harmful processes inherent in psychosis.
Developmental Trajectory of Theory-of-Mind Decline in Older Adults
