Both creativity and schizotypy are suggested to be manifestations of the hyperactivation of unusual or remote concepts/words. However, the results of studies on creativity in schizophrenia are diverse, possibly due to the multifaceted aspects of creativity and difficulties of differentiating adaptive creativity from pathological schizotypy/positive symptoms. To date, there have been no detailed studies comprehensively investigating creativity, positive symptoms including delusions, and their neural bases in schizophrenia. In this study, we investigated 43 schizophrenia and 36 healthy participants using diffusion tensor imaging. We used idea, design, and verbal (semantic and phonological) fluency tests as creativity scores and Peters Delusions Inventory as delusion scores. Subsequently, we investigated group differences in every psychological score, correlations between fluency and delusions, and relationships between these scores and white matter integrity using tract-based spatial statistics (TBSS). In schizophrenia, idea and verbal fluency were significantly lower in general, and delusion score was higher than in healthy controls, whereas there were no group differences in design fluency. We also found positive correlation between phonological fluency and delusions in schizophrenia. By correlation analyses using TBSS, we found that the anterior part of corpus callosum was the substantially overlapped area, negatively correlated with both phonological fluency and delusion severity. Our results suggest that the anterior interhemispheric dysconnectivity might be associated with executive dysfunction, and disinhibited automatic spreading activation in the semantic network was manifested as uncontrollable phonological fluency or delusions. This dysconnectivity could be one possible neural basis that differentiates pathological positive symptoms from adaptive creativity.
Creativity has long been thought as the ability to produce original, novel, flexible, and useful ideas that are free from established mental habit. One of the most commonly used definitions is “the production of effective novelty” (Mumford, 2003). A number of factors are thought to be related to creativity, such as divergent thinking (Guilford, 1959), openness (Dollinger et al., 2004), handedness (Shobe et al., 2009), language (Leonhard and Brugger, 1998), problem solving, adaptability, self-expression, quality of life (Runco, 2004), artistry (Bhattacharya and Petsche, 2002 and Bhattacharya and Petsche, 2005), magical ideation (Badzakova-Trajkov et al., 2011), and schizotypy (Fisher et al., 2004).
Both creativity and schizotypy are suggested to be manifestations of the hyperactivation of unusual or remote concepts/words (Mohr et al., 2001). Therefore, relationships between creativity and schizophrenia-spectrum disorder have been widely investigated (Sass, 2000 and Nelson and Rawlings, 2010). Indeed, a study reported that schizophrenia patients tended to engage in artistic occupation (Kyaga et al., 2011). However the results of studies on creativity in schizophrenia are varied. Some studies reported enhanced mental imagery manipulation in schizophrenia using jigsaw puzzle task (Benson and Park, 2013), whereas other studies reported lower figural creativity using the Berlin Intelligence Structure Test (Jaracz et al., 2012) or lower creativity in general using design, idea, and word fluency tests (Nemoto et al., 2007) in schizophrenia. One possible reason for these inconsistencies may be found in the differences in definition and measurement methods of creativity. Furthermore, Tsakanikos et al. reported that increased positive schizotypy or positive symptoms had relationships with increased creativity, whereas negative schizotypy or negative symptoms could be related to reduced creativity (Tsakanikos and Claridge, 2005). Thus, the clinical background of patients should also be taken into account in respect to such inconsistencies.
In previous literature investigating the semantic priming effect, it has been suggested that enhanced automatic spreading activation in semantic networks is associated with creativity (Tsakanikos and Claridge, 2005), and might underlie some of the positive symptoms (Spitzer, 1997) such as thought disorder (Kreher et al., 2008), hallucination (Lindamer and Whitman, 1997 and Kerns et al., 1999), or delusion (Debruille et al., 2007) in schizophrenia. Thus, it is reasonable to ask the following questions: what is the difference between creativity and positive symptoms, or why could hyperactivation result in innovative output in one case, but in psychotic symptoms in another? Fisher et al., in dealing with these questions, suggested that frontal lobe functions, i.e., executive functions such as monitoring, controlling, or inhibiting ability, play pivotal roles in the use of semantic information and differentiate creativity from psychopathology (Fisher et al., 2013).
Therefore, in this study, we aimed to examine creativity in schizophrenia patients with multiple creativity measures with and without semantic contents, and to investigate its impact on psychopathology, especially on positive symptoms. We predicted that overall creativity performance in schizophrenia might increase or decrease depending on the proportion of positive and negative symptoms, and that some creativity measures would positively correlate with positive symptoms. Furthermore, we hypothesized that this correlation between creativity and pathological, positive symptoms would be underpinned by the pathology of the frontal lobe structure. One of the influential hypotheses of schizophrenia, “the disconnection hypothesis” (Friston, 1998), assumes that dysconnectivity among multiple neural systems might underlie some symptoms of schizophrenia, mainly positive symptoms. We therefore utilized diffusion tensor imaging (DTI) to investigate the structural connectivity, and examined its relation with creativity and psychopathology.
