Abstract: Mental disorders such as schizophrenia, major depressive disorder, autism spectrum disorders, and various psychoses exhibit incredibly diverse clinical presentations, with symptoms varying significantly among patients. Numerous studies have provided substantial evidence that genetic factors play a major role in the development of such conditions, particularly schizophrenia. However, the genetics of schizophrenia and other mental disorders are highly complex. The development of these diseases is influenced not only by genetic factors, but also by other, often unidentified, contributors. For a long time, this led to the belief that the pathogenesis of major psychiatric disorders—primarily schizophrenia—could not be directly linked to transmissible processes. In other words, it was considered impossible for a mental illness to be transmitted from one person to another. In recent years, however, some findings have challenged this assumption. There have been reports of schizophrenia-like symptoms emerging in recipients of bone marrow transplants from donors diagnosed with schizophrenia, as well as cases of sustained remission in patients with schizophrenia following transplantation from donors without any psychiatric history. Experimental animal models have also provided evidence supporting the plausibility of such a mechanism. While these mechanisms cannot alter the recipient’s genotype, they likely have the potential to initiate or suppress pathological processes. At present, there is no widely accepted biological explanation for how these effects occur. Nonetheless, ongoing research in this area appears crucial for understanding the pathogenesis of mental disorders and for developing innovative therapeutic strategies. The aim of this review is to summarize current research on the potential role of transmissible mechanisms in schizophrenia and other neuropsychiatric disorders, and to explore how these findings may inform the development of novel therapeutic approaches.