Abstract
Dear Editor
The recently published article by Wong et al. (2014) is both exciting and important. It demonstrates a prevalence rate of hikikomori estimated at 1.9% among individuals aged 12–29 years in Hong Kong. Hikikomori is a syndrome of severe social withdrawal, characterized by persistent isolative behavior in one’s home and avoidance of social interaction. In countries like Japan as well as Korea (where it is referred to as oiettolie), concerns about hikikomori have led to nationally funded research and intervention efforts.
One of the great strengths of Wong and colleague’s study was random sampling using mobile telephone numbers. Hikikomori is, almost by definition, a challenging condition to study given the individual’s prolonged social withdrawal; in our own research, we are aware of the potential for selection bias due to this (Teo et al., 2014). This study overcame this challenge by conducting a telephone-based survey, and it allowed the researchers to reasonably generalize their results to the entire population of Hong Kong.
We would like to suggest that the prevalence of hikikomori in Hong Kong may be higher than reported in their article. Wong and colleagues defined hikikomori mostly in line with our prior proposed definition (Teo & Gaw, 2010), requiring (1) spending most of the day and nearly every day confined to home, (2) persistently avoiding social situations and social relationships, (3) duration of at least 6 months and (4) considering the social withdrawal behavior problematic. This definition, however, appears to leave out individuals who endorse impairment in daily functioning. As 12% of the overall sample did have functional impairment, we suspect some of these individuals who also met the other criteria would have been ultimately classified as hikikomori.
We applaud Wong and colleagues for using a clear and reproducible definition of hikikomori, and we hope their work will help further stimulate further research on the nature and extent of hikikomori. A future research study could compare characteristics of individuals with and without self-reported functional impairment to help determine whether this criterion is necessary or useful. More generally, we encourage funding and support for research on the influence of cultural phenomena on the expression of mental illness and practice of psychiatry worldwide.