Do you sometimes get concerned that friends are not really loyal or trustworthy? Do you often pick up hidden threats or put-downs from what people say or do? Research suggests that a few adults (10%-15%) report paranoid-like thoughts and high levels of social mistrust as well as a host of psychological problems including anxiety, insomnia and poor emotional functioning. However, it remains unclear whether such paranoid-like thoughts exist developmentally in non-clinical adolescents and children. 

Another unanswered and important question pertains to the genetic and environmental influences of social mistrust.

Twin studies of young adults in the general population have suggested moderate to high (about 50%) heritability estimates in paranoid ideation, but no study to date has examined the heritability of social mistrust, an attenuated form of paranoia, in younger populations. 

To resolve the questions mentioned above, Dr. Raymond Chan's team from the Neuropsychology and Applied Cognitive Neuroscience Laboratory, Chinese Academy of Sciences, together with his international collaborators from Cambridge University, UK and University of Utah School of Medicine, USA, has carried out a large cross-sectional survey of 8 to 14 year-old Chinese twins (N=2094),

They used a new dimensional measure of childhood suspiciousness: the Social Mistrust Scale (SMS) to conduct the research.  

This study confirmed the three-factor structure of SMS with three factors: home mistrust, school mistrust, and the general mistrust.

Replicating similar findings in adults, social mistrust existed on a continuum of severity and was positively skewed, with many children being trusting and a few being mistrustful.  

In addition, the twin study design also demonstrated moderate heritability of childhood social mistrust (19%-40%), with significant shared environmental effects (24%-50%) and specific environmental effects (36%-50%) on all levels of social mistrust as well.  

Additionally, SMS was also found to have a good discrimination to differentiate a group of 32 childhood-onset schizophrenia patients from 34 matched typically developing children.  

This study has systematically examined the prevalence, structure, and heritability of childhood social mistrust in mainland Chinese children and adolescents, providing invaluable cross-cultural evidence to the existing adult literature and theory of paranoia.  

The paper is now available in Schizophrenia Research entitled "Suspiciousness in young minds: Convergent evidence from non-clinical, clinical and community twin samples". 

This study was supported by the Beijing Municipal Science & Technology Commission Grant, the National Key Research and Development Programme, the Beijing Training Project for the Leading Talents in Science & Technology, the CAS Key Laboratory of Mental Health, Institute of Psychology, and the CAS/SAFEA International Partnership Programme for Creative Research Teams.