Date Published: February 28, 2019
Publisher: Public Library of Science
Author(s): Laura A. Steenhuis, Gerdina H. M. Pijnenborg, Jim van Os, André Aleman, Maaike H. Nauta, Agna A. Bartels-Velthuis, Sarah Whittle.
Theory of Mind (ToM) is often impaired in early and chronic phases of psychosis and it is often suggested that poor ToM is a trait vulnerability for psychosis. The aim of this study was to examine in an adolescent sample whether childhood ToM abilities can predict psychotic experiences over a period of six years and whether this is mediated by social functioning. To examine whether ToM is a specific predictor for psychosis, symptoms of depression and anxiety were also examined.
A baseline case-control sample (T0: age 7–8 years) with and without auditory vocal hallucinations (AVH) in the general population was assessed after five years (T1: age 12–13 years) on ToM ability (ToM Storybook Frank), and after eleven years (T2: age 18–19 years) on psychotic experiences (Community Assessment of Psychic Experiences; CAPE), depressive and anxiety symptoms (Depression Anxiety and Stress Scale; DASS-21), and social functioning (Groningen Questionnaire on Social Behaviour; GSVG-45). Analyses were conducted on a subsample of 157 adolescents aged 18–19 years (T2) who had data available on ToM ability at T1.
ToM at T1 was not predictive of psychotic experiences after six years (from age 12–13 to age 18–19) and social functioning was also not a mediator. ToM was not associated with psychopathology in general (depressive and anxiety symptoms) over six years (from age 12–13 to age 18–19).
The current study found no evidence for a longitudinal association between ToM ability and psychotic experiences, social functioning, and symptoms of depression and anxiety, in adolescence.
Psychotic disorders often co-occur with deficits in social cognition , which are found to contribute considerably to the impairment in social functioning associated with these disorders . Theory of Mind (ToM) is a domain of social cognition , and is defined as the ability to represent human mental states or making inferences about someone else’s intentions or emotions . Since Frith (1992)  hypothesized that ToM deficits may account for the development of (amongst others) delusions and third-person auditory hallucinations, ToM has been investigated extensively in psychotic disorders . There is evidence that ToM is impaired in multiple phases of psychosis, such as in acute psychosis , first episode psychosis , individuals at risk for psychosis [9,10] and first-degree relatives of individuals with schizophrenia . In addition, ToM ability often does not necessarily fluctuate with symptoms , suggesting that a deficit in ToM may be a trait marker for psychosis rather than a state-related factor [7,11], though not all evidence is consistent with this . It is important to investigate when the ToM vulnerability for psychosis can be ‘detected’ as to examine, as a first step, whether and when early interventions may be possible and effective. Given that psychotic experiences are prevalent in samples of youth [13–15], and may signify a precursor to psychotic disorders , it is fruitful to examine whether poorer ToM is associated with psychotic experiences during adolescence.
The 157 participants at T2 had a mean age of 18.9 years (SD = 0.35, range 18.2–19.9). At baseline, 76 reported AVH and 81 did not (X2 = 0.05, p = 0.83). Significantly more females participated in this study (57.3%) compared to males (X2 = 12.2, p = 0.001), but there were no significant differences between males and females in ToM ability at T1 (males: M = 26.60, SD = 5.01, females: M = 27.18, SD = 5.01, t(155) = .519, p = .605) and in the frequency of psychotic experiences at T2 (males: M = 4.12, SD = 4.42, females: M = 4.44, SD = 4.36, t(149) = .630, p = .530).
In line with the idea that poor ToM ability may represent a vulnerability for developing psychosis [7,11], the current study examined in a general population sample of adolescents whether poorer ToM ability at age 12–13 years was associated with the frequency of psychotic experiences at age 18–19 years. In addition, it was examined whether social functioning at age 18–19 years mediates this relationship. Contrary to our expectations, we did not find evidence that poorer ToM ability in childhood was longitudinally associated to increased psychotic experiences in adolescence over a period of six years. This was confirmed in a post-hoc exploration when examining the bottom 10% of scorers on the ToM task, again establishing no evidence for increased psychotic experiences. Social functioning was therefore not identified as a mediator between ToM ability and psychotic experiences. Similarly, ToM ability did not predict symptoms of anxiety or depression over six years’ time. The findings imply that in the current adolescent general population sample, ToM ability was not a vulnerability factor for psychotic experiences, social functioning, or for depression and anxiety.