Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 0 0 2026 08 08 1 11 Teng Xie School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, China Zhihao Li Department of Traditional Chinese Medicine, Sichuan Food and Drug School, Leshan, China AND Office of Academic Affairs, Sichuan Vocational and Technical College of Quality Engineering, Leshan, China 2025 05 21 2026 02 08 In recent years, the incidence of psychiatric disorders has been steadily increasing, posing significant challenges to both individual health and social stability. Emerging evidence has highlighted a close association between immune cells and the onset and progression of various psychiatric conditions. Traditional approaches for inferring causality, such as randomized controlled trials and observational studies, are often limited by feasibility, bias, and confounding factors. Mendelian randomization (MR), which leverages genetic variants as instrumental variables, provides a powerful alternative for assessing causal relationships between immune cells and psychiatric disorders. This review summarizes recent advances in MR studies investigating the causal links between immune cell profiles and psychiatric disorders, including anxiety, depression, and schizophrenia. By integrating current evidence from MR studies, this review aims to provide new insights and reference points for future research exploring the relationship between immune cells and psychiatric disorders. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/4452 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/4452/2385