Association between decreased taurine levels in the anterior cingulate cortex and restricted and repetitive behaviors in autism spectrum disorder: A cross-sectional study

Akihiro Minami¹Kiwamu Matsuoka¹Masato Takahashi¹Kazuya Ueda¹Hiroki Ohnishi¹Yuka Fujimoto¹Hiroaki Yoshikawa¹Rio Ishida¹Yuhei Takado^2,3Jamie Near⁴Yuya Yamatani¹Toshiteru Miyasaka¹Yumi Tai¹Tomoko Ochi¹Toshihiro Tanaka¹Takashi Okada¹Nakao Iwata⁵Manabu Makinodan^5*

• ¹Nara Kenritsu Ika Daigaku, Kashihara, Japan
• ²Sichuan University Department of General Dentistry, Chengdu, China
• ³Kokuritsu Kenkyu Kaihatsu Hojin Ryoshi Kagaku Gijutsu Kenkyu Kaihatsu Kiko Ryoshi Seimei Igaku Bumon Ryoshi Seimei Kagaku Kenkyujo, Chiba, Japan
• ⁴Sunnybrook Research Institute, Toronto, Canada
• ⁵Fujita Ika Daigaku, Toyoake, Japan

Children with autism spectrum disorder (ASD) often experience reduced quality of life due to core autistic traits, such as restricted and repetitive behaviors (RRBs), yet no pharmacological treatments have been established to date. Oxidative stress, a potential contributor to ASD pathology, may reduce taurine and glutathione (GSH) levels. Although animal studies have reported altered antioxidant levels, studies investigating the brain antioxidant levels in individuals with ASD remain limited. This study investigated whether reduced antioxidant levels in the anterior cingulate cortex (ACC), a region consistently characterized by functional and metabolic abnormalities in individuals with ASD, and closely associated with RRBs. A total of 44 children with ASD and 40 typically developing controls were enrolled in this study. Diagnoses were confirmed using the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2). Magnetic resonance spectroscopy was used to quantify taurine and GSH levels in the ACC. Statistical analyses were conducted to compare metabolite levels between the groups and assess associations with ADOS-2 subscale scores. The ASD group exhibited significantly lower taurine levels, whereas GSH levels remained unchanged. Taurine levels were negatively correlated with RRBs but not with social affect. These findings suggest that reduced taurine levels in the ACC of children with ASD, alongside unchanged GSH levels, may indicate distinct biosynthetic pathways and functional roles of these metabolites in oxidative stress defense mechanisms associated with ASD pathology. Taurine depletion may disrupt physiological processes associated with RRBs and could serve as a potential therapeutic target for symptom management.