The RCPsych Article of the Month for May is ‘International experience of hikikomori (prolonged social withdrawal) and its relevance to psychiatric research’ and the blog is written by Author Dr Marcus PJ. Tan published in BJPsych International.

Hikikomori is a Japanese term that refers to extreme social isolation. First introduced to the medical community by psychiatrist Tamaki Saito in a bestselling book in 1998, the condition has since seen much interest. In Japan, prevalence studies estimating it to occur in 1.2% of 20-49yr olds seemed to confirm anecdotal concerns from many parents worried about whether their children might suffer from the condition and attracted government attention. What could this Japanese phenomenon teach us about psychiatry elsewhere?

First, we realised that Hikikomori research has not adhered to using a standardised definition of the term. This has made it difficult to use it to draw firm conclusions. To address this, we have recommended research follows standardised diagnostic criterion proposed previously, as follows:

• marked social isolation in the person’s home
• duration of continuous social isolation of at least 6 months
• significant functional impairment or distress associated with the social isolation.

That said, more consideration on how these may be operationalised is needed. For example, how should these be interpreted in the context of the current pandemic? Should someone who does not physically meet people in person, but have contact with them online, be considered socially isolated? And what level of online contact would be considered “acceptable” in this regard?

We also realised that Hikikomori is usually comorbid with mental health disorder. Several studies that considered this did not screen for the full range of psychiatric disorder. Of the two studies that did, they found very low rates of Hikikomori to be without associated psychopathology – 1 of 337 in Japan, and 1 of 190 in Spain. This highlights the significant mental health burden that social isolation comes with – which mirrors findings from similar studies in the West.

We also realised that Hikikomori occurs around the world. That is to say, its aetiology is not “culture-bound” to Japanese society like it was first believed to be. This is not to discount the significant role that cultural issues can play in its aetiology. As an example, bullying in childhood is suggested as a stressor that could precipitate Hikikomori-like behaviour. Yet the experience of bullying might vary across cultures. Integrating research on the subject from related disciplines, such as sociology and anthropology, could help us better understand its place in Hikikomori aetiology.

In conclusion, Hikikomori may be a useful construct to study social withdrawal in the context of other mental health conditions. The use of a standardised definition in further research is urgently needed, to ensure such comparisons can be effectively made. Importantly, it would also facilitate sharing of research findings across countries and cultures. As an example, research into the use of robots to treat Hikikomori could contribute to the wider discussion on telepsychiatry, and how its reception and effectiveness may vary around the globe. It is hoped that such research would help mental health research on its way to becoming more culturally-informed, more alert to the interactions between culture, society, and the self.

‘As psychiatrists, we often find that attempts to define unambiguously the complex character of unusual mental states are plainly inadequate. Our attempts at taxonomy fail any test of precision, and the controversies that exist in plain sight are an embarrassment to our profession. There is no independent objective reality to so many conditions. Indeed, many would argue the very act of diagnosis abjures our professional recognition of deep complexity. So, how do we cope with the claim that a condition (Hikikomori) exists in Japan, but is rarely found anywhere else in the world? Tan and colleagues discuss these challenging issues in their Article of the Month.’

Professor David Skuse