Maladaptive social interaction and its related psychopathology have been 
highlighted in psychiatry especially among younger generations. In Japan, novel 
expressive forms of psychiatric phenomena such as "modern-type depression" and 
"hikikomori" (a syndrome of severe social withdrawal lasting for at least six 
months) have been reported especially among young people. Economic games such as 
the trust game have been utilized to evaluate real-world interpersonal 
relationships as a novel candidate for psychiatric evaluations. To investigate 
the relationship between trusting behaviors and various psychometric scales, we 
conducted a trust game experiment with eighty-one Japanese university students 
as a pilot study. Participants made a risky financial decision about whether to 
trust each of 40 photographed partners. Participants then answered a set of 
questionnaires with seven scales including the Lubben Social Network Scale 
(LSNS)-6 and the Patient Health Questionnaire (PHQ)-9. Consistent with previous 
research, male participants trusted partners more than female participants. 
Regression analysis revealed that LSNS-family (perceived support from family) 
for male participants, and item 8 of PHQ-9 (subjective agitation and/or 
retardation) for female participants were associated with participants' trusting 
behaviors. Consistent with claims by social scientists, our data suggest that, 
for males, support from family was negatively associated with cooperative 
behavior toward non-family members. Females with higher subjective agitation 
(and/or retardation) gave less money toward males and high attractive females, 
but not toward low attractive females in interpersonal relationships. We believe 
that our data indicate the possible impact of economic games in psychiatric 
research and clinical practice, and validation in clinical samples including 
modern-type depression and hikikomori should be investigated.