Association between same-sex partnership certificate schemes and mental health in sexual and gender minority adults: nationwide cross-sectional study in Japan.
Residing in a municipality with partnership certificate schemes was not associated with better mental health among sexual and gender minority people in Japan, and was associated with higher rates of suicidal thoughts compared to municipalities without such schemes.
Key Findings
Results
SGM adults residing in municipalities with partnership certificate schemes reported significantly higher rates of suicidal thoughts compared to those in municipalities without such schemes.
Average marginal effect (AME) for suicidal thoughts in the SGM group: +5.1 percentage points (pp); 95% CI +0.4 to +9.8 pp
This finding was statistically significant
Analysis adjusted for sociodemographic characteristics, health status, and municipal characteristics
The outcome was self-reported suicidal thoughts
Results
Cisgender heterosexual adults residing in municipalities with partnership certificate schemes reported significantly lower rates of suicidal thoughts compared to those in municipalities without such schemes.
AME for suicidal thoughts in the cisgender heterosexual group: -1.6 pp; 95% CI -3.0 to -0.1 pp
This finding was statistically significant
The direction of effect was opposite to that observed in the SGM group
Results
The relative difference in suicidal thoughts between SGM and cisgender heterosexual adults comparing municipalities with versus without partnership certificate schemes was statistically significant.
Relative difference: +6.7 pp; 95% CI +1.8 to +11.5 pp
This represents the difference-in-differences estimate comparing SGM and cisgender heterosexual groups across municipality types
The positive relative difference indicates SGM adults fared worse relative to cisgender heterosexual adults in municipalities with PCSs
Results
No significant difference in mental distress was found between SGM adults residing in municipalities with versus without partnership certificate schemes.
Mental distress was measured using the Kessler 6 Scale with a threshold score of ≥5
The difference in mental distress rates was not statistically significant for the SGM group
This null finding contrasts with the significant finding for suicidal thoughts
Methods
The study sample included 28,106 participants from a nationwide internet survey in Japan, of whom 11.3% identified as SGM.
Total participants: 28,106
Mean (SD) age: 48.2 (17.3) years
SGM individuals: 3,169 (11.3%)
Data were collected in September and October 2022
Participants were adults aged ≥18 years
Discussion
The authors hypothesize that partnership certificate schemes without national legislation may worsen SGM mental health by highlighting inequality with legal marriage, failing to address internalised stigma, and potentially lowering self-esteem.
Proposed mechanisms include limited scheme uptake, perceptions of inequality compared to legal marriage, failure to promote acceptance, and lowered self-esteem among SGM people
The authors note these schemes lack legal recognition, distinguishing them from same-sex marriage legalisation
The authors contrast their findings with evidence that same-sex marriage legalisation improves mental health among SGM people
What This Means
This research examined whether living in a Japanese municipality that offers 'partnership certificates' to same-sex couples — a form of social recognition without legal rights — was associated with better mental health among sexual and gender minority (SGM) people. Using data from over 28,000 adults surveyed across Japan in 2022, the researchers compared rates of psychological distress and suicidal thoughts among SGM and non-SGM people living in municipalities with and without these certificate schemes. Contrary to what might be expected, SGM adults in municipalities with the certificate schemes actually reported higher rates of suicidal thoughts (about 5 percentage points higher) compared to SGM adults in municipalities without the schemes, while non-SGM adults showed the opposite pattern.
This research suggests that symbolic recognition policies like partnership certificates, when not backed by full legal equality, may not improve — and could potentially worsen — the mental health of SGM individuals. The authors propose several possible explanations: the certificates may serve as a reminder of unequal status compared to legal marriage, they may do little to reduce internalized stigma or promote societal acceptance, and they may actually lower self-esteem among SGM people by institutionalizing a 'second-class' form of recognition. These findings stand in contrast to evidence from countries where same-sex marriage has been fully legalized, where mental health improvements among SGM people have been documented.
The study has important implications for policymakers considering incremental steps toward SGM rights. It suggests that partial or symbolic measures may not deliver the mental health benefits seen with full legal equality, and could even be counterproductive. The authors call for further research to better understand the mechanisms behind this association, noting that this was a cross-sectional study and cannot establish causation. The findings may also reflect the specific social and legal context of Japan, where same-sex marriage remains unrecognized at the national level.
Tatsuno Y, Minami T, Tomio J, Tabuchi T, Miyawaki A. (2026). Association between same-sex partnership certificate schemes and mental health in sexual and gender minority adults: nationwide cross-sectional study in Japan.. BMJ open. https://doi.org/10.1136/bmjopen-2025-106055