Hiroki Kawai

Mr. Hiroki Kawai

neuropsychiatry, Okayama University Hospital, Okayama, Japan
orcid

Research Focus & Metrics

Academic Career Length

4Years (2023-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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HKHiroki Kawai
Hiroki Kawai
MKMakiko Kishimoto
Makiko Kishimoto
YOYuko Okahisa
Yuko Okahisa
SSShinji Sakamoto
Shinji Sakamoto
STSeishi Terada
Seishi Terada
MTManabu Takaki
Manabu Takaki
Sensory impairments are common features of autism spectrum disorder (ASD) and are associated with its social impairments. However, there is no established treatment for these impairments in adults with ASD. The Safe & Sound Protocol (SSP) is a listening program designed to improve social communication skills by reducing auditory hypersensitivity. We investigated the effectiveness of the SSP for adults with ASD. We administered the SSP to six participants with ASD aged 21–44 years old, and the effects were assessed using the Social Responsiveness Scale, Second Edition (SRS-2). Secondary outcomes were assessed using the Center for Epidemiological Studies Depression Scale (CES-D), State-Trait Anxiety Inventory (STAI), WHO Quality of Life 26 (WHOQOL-BREF), and Adolescent/Adult Sensory Profile (A/ASP). In this study, only the Social Awareness scale of the SRS-2 Family-Report showed a significant improvement after the intervention. In addition, it was significantly correlated with physical health of WHOQOL-BREF (r = −0.577, p = 0.012), state and trait anxiety of STAI (r = 0.576, p = 0.012; r = 0.708, p = 0.00009, respectively), and CES-D (r = 0.465, p = 0.05). In conclusion, the SSP has a partial effect on social impairments in adults with ASD, specifically on the Social Awareness subscale of the SRS-2.

31 December 2025 in Journal of Metaverse
Verified
Journal Article
Open access
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Joe HaseiJoe Hasei
Joe Hasei
YMYosuke Matsumoto
Yosuke Matsumoto
HKHiroki Kawai
Hiroki Kawai
YOYuko Okahisa
Yuko Okahisa
MTManabu Takaki
Manabu Takaki
TOToshifumi Ozaki
Toshifumi Ozaki
This study explored whether metaverse-based support groups could address social isolation and suicide risks among LGBTQ+ youths by providing enhanced anonymity, avatar-based self-expression, and improved accessibility. Over one year, 53 individuals aged 14–23 participated in regular online sessions facilitated via the "cluster" metaverse platform by a non-profit LGBTQ+ organization. Each 90-minute session included voice and text-based interactions within a specially designed single-floor virtual space featuring conversation areas and a designated "safe area" for emotional regulation. Post-session questionnaires (5-point Likert scales) captured demographics, avatar preferences, self-confidence, and perceived safety, self-expression, and accessibility; responses were analyzed with Pearson's chi-squared test and Mann–Whitney U tests (α=0.05). Results indicated that 79.2% of participants selected avatars aligned with their gender identity, reporting high satisfaction (mean = 4.10/5) and minimal discomfort (mean = 1.79/5). Social confidence was significantly higher in the metaverse compared with real-world settings (p

14 June 2025 in Neuroscience Research
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Journal Article
Open access
HNHoang Duy Nguyen
Hoang Duy Nguyen
HMHaruko Miyazaki
Haruko Miyazaki
HKHiroki Kawai
Hiroki Kawai
ZWZiyi Wang
Ziyi Wang
SSShinji Sakamoto
Shinji Sakamoto
TOToshitaka Oohashi
Toshitaka Oohashi
Anorexia nervosa (AN) is an eating disorder characterized by restricted energy intake, severely underweight status, and frequent hyperactivity. Previous research has shown structural and functional alterations in the medial prefrontal cortex (mPFC) and hippocampus of AN patients. To investigate the pathological mechanism of AN, we analyzed the expression and distribution of parvalbumin (PV) interneurons and perineuronal nets (PNNs), which are implicated in the pathology of neuropsychiatric disorders, in the mPFC and hippocampus dorsal (HPCd) and ventral (HPCv) using an activity-based anorexia (ABA) mouse model. We found that PNN expression and density increased in the mPFC, with minor alterations in the HPCd and HPCv of ABA mice. The expression and distribution of PV neurons were unchanged in the brains of ABA mice, except for a regional decrease in PV-expressing neuron density in the HPCd. Co-localization analysis showed an increased number of PNNs enwrapping PV-negative neurons in the mPFC of ABA mice. Furthermore, the upregulation of PNN expression in the mPFC was positively correlated with elevated blood corticosterone levels, a well-known stress indicator, in ABA mice. Our findings suggest that the increased expression and distribution of PNNs surrounding PV-negative neurons in the mPFC may indicate the pathological mechanisms of AN.

24 September 2025 in International Journal of Eating Disorders
Verified
Journal Article
Open access
HKHiroki Kawai
Hiroki Kawai
NWNanami Wada
Nanami Wada
SSShinji Sakamoto
Shinji Sakamoto
KMKenji Miyazaki
Kenji Miyazaki
TKTaro Kato
Taro Kato
MTManabu Takaki
Manabu Takaki
Objective: Anorexia nervosa (AN) is a metabolic‐psychiatric disorder characterized by severe weight loss, hypercortisolemia, and hypothalamic–pituitary–adrenal (HPA) axis activation. In this study, we investigated the effect of inhibiting cortisol regeneration via the enzyme 11β‐hydroxysteroid dehydrogenase type 1 (11β‐HSD1) on the pathophysiology of AN. Method: Female C57BL/6J mice underwent a 7‐day activity‐based anorexia (ABA) paradigm, involving 3 h daily feeding and free access to wheels, until 25% body weight loss or experiment completion. Mice were orally treated once daily with a potent 11β‐HSD1 inhibitor, DSOK‐0011, or vehicle. Body weight, food intake, and activity transitions were recorded; plasma corticosterone and cholesterol levels were measured using a fluorometric assay; gut microbiota were analyzed using 16S rRNA sequencing; and hippocampal glial cells were analyzed using immunohistochemistry. Results: DSOK‐0011‐treated mice exhibited a modest but significant increase in postprandial wheel‐running activity compared to baseline (4–5 p.m., p = 0.018; 5–6 p.m., p = 0.043), whereas vehicle‐treated mice showed higher preprandial activity (9–10 a.m., p = 0.0229). Gut microbiota analysis revealed increased alpha diversity in ABA mice, with a specific enrichment of the Lachnospiraceae family in the DSOK‐0011 group. However, DSOK‐0011 did not significantly affect body weight, food intake, corticosterone, and lipid levels, or hippocampal glial cell populations. Conclusion: Inhibition of 11β‐HSD1 by DSOK‐0011 was associated with microbiota alterations and subtle shifts in activity timing under energy‐deficient conditions. These findings suggest that peripheral glucocorticoid metabolism may influence microbial and behavioral responses in the ABA model, although its metabolic impact appears limited in the acute phase.