Suicide is one of the most critical issues worldwide. In Japan, more than 30 000 people died by suicide every year between 1998 and 2011, and the Japanese government, local governments, and various other agencies have been working on suicide prevention programs to reduce the suicide rate. While the number of suicides is still high (more than 20 000 per year), many specialists are striving to further reduce the number of suicides in Japan. The Japanese government has played a central role in suicide prevention through the enactment of several laws, and in recent years, suicide prevention has shifted from government to community‐specific measures. This review discusses the suicide prevention measures that have been taken so far: (1) policy strategies for suicide prevention by the Japanese government, (2) community suicide prevention, and (3) strategic studies for suicide prevention. Finally, as shown in the ACTION‐J study, we conclude that cooperation among related organizations in the community, not just one institution, is important for future suicide prevention, especially youth suicide prevention.

During brain development, the design of primary neural networks is primarily determined by environmental stimuli after their formation. In particular, the juvenile period is critical, during which neuronal circuits that consist of both excitatory and inhibitory neurons are remodeled by experience. Social isolation during the juvenile period profoundly affects brain development and contributes to the development of psychiatric disorders. We previously reported that 2 weeks of social isolation after weaning reduced excitatory synaptic inputs and intrinsic excitability in a subtype of layer 5 pyramidal cells, which we defined as prominent h-current (PH) cells, in the medial prefrontal cortex (mPFC) in mice. However, it remains unclear how juvenile social isolation affects inhibitory neuronal circuits that consist of pyramidal cells and interneurons. We found that 2 weeks of social isolation after weaning increased inhibitory synaptic inputs exclusively onto PH cells with a concomitant deterioration of action potential properties. Although social isolation did not alter the inhibitory synaptic release mechanisms or the number of inhibitory functional synapses on PH cells, we found that it increased the intrinsic excitability of fast-spiking (FS) interneurons with less excitatory synaptic inputs and more h-current. Our findings indicate that juvenile social isolation enhances the activity of inhibitory neuronal circuits in the mPFC.

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A lack of juvenile social experience causes various behavioral impairments and brain dysfunction, especially in the medial prefrontal cortex (mPFC). Our previous studies revealed that juvenile social isolation for 2 weeks immediately after weaning affects the synaptic inputs and intrinsic excitability of fast-spiking parvalbumin-expressing (FSPV) interneurons as well as a specific type of layer 5 (L5) pyramidal cells, which we termed prominent h-current (PH) cells, in the mPFC. However, since these changes were observed at the adult age of postnatal day 65 (P65), the primary cause of these changes to neurons immediately after juvenile social isolation (postnatal day 35) remains unknown. Here, we investigated the immediate effects of juvenile social isolation on the excitability and synaptic inputs of PH pyramidal cells and FSPV interneurons at P35 using whole-cell patch-clamp recording. We observed that excitatory inputs to FSPV interneurons increased immediately after juvenile social isolation. We also found that juvenile social isolation increases the firing reactivity of a subtype of FSPV interneurons, whereas only a fractional effect was detected in PH pyramidal cells. These findings suggest that juvenile social isolation primarily disturbs the developmental rebuilding of circuits involving FSPV interneurons and eventually affects the circuits involving PH pyramidal cells in adulthood.

Aim Suicide attempters have a high risk of repeated suicide attempts and completed suicide. There is evidence that assertive case management can reduce the incidence of recurrent suicidal behavior among suicide attempters. This study evaluated the effect of an assertive‐case‐management training program. Methods This multicenter, before‐and‐after study was conducted at 10 centers in Japan. Participants were 274 medical personnel. We used Japanese versions of the Attitudes to Suicide Prevention Scale, the Gatekeeper Self‐Efficacy Scale, the Suicide Intervention Response Inventory (SIRI), and the Attitudes Toward Suicide Questionnaire. We evaluated the effects with one‐sample t‐tests, and examined prognosis factors with multivariable analysis. Results There were significant improvements between pre‐training and post‐training in the Attitudes to Suicide Prevention Scale (mean: −3.07, 95% confidence interval [CI]: −3.57 to −2.57, P < 0.001), the Gatekeeper Self‐Efficacy Scale (mean: 10.40, 95%CI: 9.48 to 11.32, P < 0.001), SIRI‐1 (appropriate responses; mean: 1.15, 95%CI: 0.89 to 1.42, P < 0.001), and SIRI‐2 (different to the expert responses; mean: −4.78, 95%CI: −6.18 to −3.38, P < 0.001). Significant improvements were found on all Attitudes Toward Suicide Questionnaire subscale scores, except Unjustified Behavior. The effect of training was influenced by experience of suicide‐prevention training and experience of working with suicidal patients. Conclusion The training program (which was developed to implement and disseminate evidence‐based suicide‐prevention measures) improved attitudes, self‐efficacy, and skills for suicide prevention among medical personnel. Specialized suicide‐prevention training and experience with suicidal patients are valuable for enhancing positive attitudes and self‐efficacy; furthermore, age and clinical experience alone are insufficient for these purposes.