Mental disorders are complex illnesses with multifactorial etiologies involving genetic and environmental components. This review focuses on cellular models derived from the olfactory epithelium as a promising tool to study the molecular mechanisms of some neuropsychiatric diseases. The authors consider cell lines allowing the identification of potential biomarkers and pathogenetic mechanisms of schizophrenia, bipolar disorder, and Alzheimer’s disease. Advantages of these models include the preservation of epigenetic modifications, the possibility of studying intercellular interactions, and conducting personalized studies. Particular emphasis is placed on state-of-the-art analytical techniques, such as single-cell RNA sequencing and DNA methylation analysis, as well as non-invasive methods of obtaining cellular material. The use of these models opens up new perspectives for the development of personalized therapeutic approaches and optimizing existing treatment regimens for psychiatric disorders.