The definition of “hikikomori”—people who avoid social participation and generally stay at home—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 the University of Tsukuba have 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.

Although the need for support for hikikomori has recently been increasing, how to define hikikomori in terms of patient characteristics has rarely been discussed.

In a study published in Psychiatry and Clinical Neurosciences, 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.