A form of severe social withdrawal, called hikikomori, has been frequently 
described in Japan and is characterized by adolescents and young adults who 
become recluses in their parents' homes, unable to work or go to school for 
months or years. The aim of this study was to review the evidence for hikikomori 
as a new psychiatric disorder. Electronic and manual literature searches were 
used to gather information on social withdrawal and hikikomori, including 
studies examining case definitions, epidemiology, and diagnosis. A number of 
recent empirical studies have emerged from Japan. The majority of such cases of 
hikikomori are classifiable as a variety of existing Diagnostic and Statistical 
Manual (DSM) psychiatric disorders. However, a notable subset of cases with 
substantial psychopathology does not meet criteria for any existing psychiatric 
disorder. We suggest hikikomori may be considered a culture-bound syndrome and 
merits further international research into whether it meets accepted criteria as 
a new psychiatric disorder. Research diagnostic criteria for the condition are 
proposed.