One of his most important contributions to science has been to help provide the scientific foundation of the century-old postulate that schizophrenia debuts with cognitive dysfunction—preceding the onset of the first psychosis by more than a decade. Moreover, he and his group have shown that brain changes in schizophrenia are progressive over time, and that these changes are clinically relevant, related as they are to outcome and to loss of cognitive function during the course of the illness. Finally, his research has shown that brain volume is one of the most heritable characteristics of man, paving the way to link brain volumes in health and disease to genetic variation. During his time in Europe he initiated several large treatment trials in schizophrenia in order to improve the outcome of patients with schizophrenia. He is also involved in many other collaborative studies, examining both genetic and neuroimaging parameters. His work has been funded by various sources such as the European Union, the Dutch Government, NIMH and the Stanley Foundation.