The knowledge in psychiatric genetics, neuroanatomy, functional neuroanatomy, neuropsychology, neuropsychopharmacology and clinical psychiatry, has immensely increased in the last decades. Here, the psychiatric conditions schizophrenia, affective disorders and autism spectrum disorder are discussed. Reported findings in relevant literature and our clinical experience in adult psychiatry in line with these findings, are subjects of this article. Disorders that in the last 100 years typically have been described as schizophrenia might today be better viewed as neurodevelopmental disorders (NDD:s), particularly autism spectrum disorder, combined with affective disorders. Also in affective disorders, without any signs and symptoms typical of a diagnosis of schizophrenia, NDD:s are very common, albeit generally less severe. The ensuing view on schizophrenia and on affective disorders respectively has very important and far reaching conceptual and clinical implications.