Prevalence of Mental Illness, Cognitive Disability, and Their Overlap among the Homeless in Nagoya, Japan

Akihiro Nishio; Mayumi Yamamoto; Ryo Horita; Tadahiro Sado; Hirofumi Ueki; Takahiro Watanabe; Ryosuke Uehara; Toshiki Shioiri

doi:10.1371/journal.pone.0138052

Prevalence of Mental Illness, Cognitive Disability, and Their Overlap among the Homeless in Nagoya, Japan

PLoS One. 2015 Sep 17;10(9):e0138052. doi: 10.1371/journal.pone.0138052. eCollection 2015.

Authors

Akihiro Nishio¹, Mayumi Yamamoto², Ryo Horita³, Tadahiro Sado⁴, Hirofumi Ueki⁵, Takahiro Watanabe⁶, Ryosuke Uehara⁷, Toshiki Shioiri⁵

Affiliations

¹ Health Administration Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan; Department of Psychopathology, Division of Neuroscience, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
² Health Administration Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan; United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
³ Health Administration Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
⁴ Health Administration Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan; Faculty of Health Promotional Sciences, Tokoha University, 1230 Kitaku, Miyakoda, Hamamatsu, 431-2102, Japan.
⁵ Department of Psychopathology, Division of Neuroscience, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
⁶ Midori Hospital, 1-14-24 Kitayama, Gifu, 501-3113, Japan.
⁷ Yoshida Hospital, 1-7-1 Saidaiji Akoda, Nara, 631-0818, Japan.

Abstract

Background: While the prevalence of mental illness or cognitive disability is higher among homeless people than the general population in Western countries, few studies have investigated its prevalence in Japan or other Asian countries. The present study conducted a survey to comprehensively assess prevalence of mental illness, cognitive disability, and their overlap among homeless individuals living in Nagoya, Japan.

Methods: Participants were 114 homeless individuals. Mental illness was diagnosed based on semi-structured interviews conducted by psychiatrists. The Wechsler Adult Intelligence Scale-III (WAIS-III, simplified version) was used to diagnose intellectual/ cognitive disability.

Results: Among all participants, 42.1% (95% CI 33.4-51.3%) were diagnosed with a mental illness: 4.4% (95% CI 1.9-9.9%) with schizophrenia or other psychotic disorder, 17.5% (95% CI 11.6-25.6%) with a mood disorder, 2.6% (95% CI 0.9-7.5%) with an anxiety disorder, 14.0% (95% CI 8.8-21.6%) with a substance-related disorder, and 3.5% (95% CI 1.4-8.8%) with a personality disorder. Additionally, 34.2% (95% CI 26.1-43.3%) demonstrated cognitive disability: 20.2% (95% CI 13.8-28.5%) had mild and 14.0% (95% CI 8.8-21.6%) had moderate or severe disability. The percent overlap between mental illness and cognitive disability was 15.8% (95% CI 10.2-23.6%). Only 39.5% (95% CI 26.1-43.3%) of the participants were considered to have no psychological or cognitive dysfunction. Participants were divided into four groups based on the presence or absence of mental illness and/or cognitive disability. Only individuals with a cognitive disability reported a significant tendency toward not wanting to leave their homeless life.

Conclusion: This is the first report showing that the prevalence of mental illness and/or cognitive disability among homeless individuals is much higher than in the general Japanese population. Appropriate support strategies should be devised and executed based on the specificities of an individual's psychological and cognitive condition.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Aged
Cognition Disorders / epidemiology*
Female
Humans
Ill-Housed Persons / psychology*
Ill-Housed Persons / statistics & numerical data*
Japan / epidemiology
Male
Mental Disorders / epidemiology*
Middle Aged
Prevalence
Young Adult

Grants and funding

The Japan Federation of the Democratic Medical Institute and the Health Administration Center, Gifu University, financed the survey. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.