Stressing schizotypy: The modulating role of stress-relieving behaviours and intellectual capacity on functional hemispheric asymmetry

Abstract

Relative cognitive impairments are common along the schizophrenia spectrum reflecting potential psychopathological markers. Yet stress, a vulnerability marker in schizophrenia (including its spectrum), is likewise related to cognitive impairments. We investigated whether one such cognitive marker (attenuated functional hemispheric asymmetry) during stressful life periods might be linked to individuals' schizotypal features or rather to individuals' stress-related experiences and behaviours. A total of 58 students performed a left hemisphere dominant (lateralised lexical decisions) and right hemisphere dominant (sex decisions on composite faces) task. In order to account for individual differences in stress sensitivity we separated participants into groups of high or low cognitive reserve according to their average current marks. In addition, participants filled in questionnaires on schizotypy (short O-LIFE), perceived stress, stress response, and a newly adapted questionnaire that enquired about potential stress compensation behaviour (elevated substance use). The most important finding was that enhanced substance use and cognitive disorganisation contributed to a right and left hemisphere shift in language dominance, respectively. We discuss that (i) former reports on right hemisphere shifts in language dominance with positive schizotypy might be explained by an associated higher substance use and (ii) cognitive disorganisation relates to unstable cognitive functioning that depend on individuals' life circumstances, contributing to published reports on inconsistent laterality–schizotypy relationships.

Keywords:

• Stress
• Drug dependence
• Schizophrenia spectrum
• Cognitive reserve
• Hemispheric asymmetry

Acknowledgments

We would like to thank Sally Easton (University of Bristol) and Michael Wilson (IUMSP) for proofreading the manuscript, and Dr Nicolas Pound (Brunel University) for providing us with the faces and the composite faces for the FDT. Work on this study was importantly stimulated by the second author's collaboration in the OPTIMI project funded by the European Union's 7th Framework Programme (Grant agreement no. 248544). Additionally we would like to thank Dr Oliver Mason (University College London) for enabling us to compare our schizotypy scores with normative values of the short O-LIFE by providing us with the original dataset, published in 2005.

Notes

1. We also assessed verbal and figural fluency performance. For economy of presentation these findings will be presented elsewhere. Data and findings from the fluency tasks can also be requested from the corresponding author.