Research News
Hikikomori Population Varies Significantly Depending on the Definition Used

The definition of "hikikomori" according to criteria used by the Japanese Cabinet Office survey, as reported in the press, differs from the diagnostic criteria for hikikomori proposed in the field of psychiatry. Researchers at University of Tsukuba found, in a survey of residents of Kasama City, Ibaraki Prefecture, that the populations described by different definitions of hikikomori had little overlap, and the prevalence rates of hikikomori differed according to the definition used.
Tsukuba, Japan—Although the need for support for "hikikomori"—people who avoid social participation and generally stay at home—has recently been increasing, how to define hikikomori in terms of patient characteristics has rarely been discussed.
In this study, researchers used two sets of criteria, which included the criteria determined by the Japanese Cabinet Office for use in the Office's nationwide survey, as well as the recently proposed psychiatric criteria for pathological hikikomori; they defined groups that met each criterion. They then conducted a survey to identify overlaps and differences between the groups. Specifically, a questionnaire survey was administered to residents of Kasama City, Ibaraki Prefecture, for a one-month period, beginning in February 2024, to determine whether respondents met either of the two criteria. The researchers analyzed the dissimilarities among three groups of hikikomori: the group of hikikomori as defined by the Japanese Cabinet Office criteria, the group of pathological hikikomori according to the psychiatric criteria, and the group of non-pathological hikikomori according to the psychiatric criteria. Their results revealed that although there was overlap among the three groups, there were also significant differences between the groups.
In many cases, the Japanese Cabinet Office's criteria were not strictly adhered to in surveys that had been conducted by municipalities . If differences in the definitions of hikikomori and the characteristics of the hikikomori population are not understood, an inaccurate understanding of withdrawal could arise . There is a need for caution when interpreting and comparing survey results . To provide support for hikikomori, one must be aware of the criteria used to diagnose the condition, and one must conduct multifaceted evaluations from various perspectives on mental health and welfare without overmedicalizing the condition.
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This work was supported by JST RISTEX "SOLVE for SDGs: Preventing Social Isolation & Loneliness and Creating Diversified Social Networks" Grant Number JPMJRX21K2, Japan.
Original Paper
- Title of original paper:
- The hikikomori population varies significantly depending on the definition used: Evidence from a survey in Kasama, Ibaraki, Japan
- Journal:
- Psychiatry and Clinical Neuroscience
- DOI:
- 10.1111/pcn.13783
Correspondence
Professor TACHIKAWA Hirokazu
Institute of Medicine, University of Tsukuba
Chief Physician, OGAWA Takafumi
Ibaraki Prefectural Medical Center of Psychiatry
Professor AIBA Miyuki
Faculty of Human Sciences, Toyo Gakuen University