Fundamental scientific research using new advanced technologies has gained a more profound insight into the molecular-biological and genetical basics of dementia. By unraveling the pathogenetic processes involved, the vision of dementia being an obscure degenerative proces has been changed. In this article we discuss the recent findings of four dementing illnesses: Alzheimer's disease, Huntington's chorea, Creutzfeldt-Jacob disease and Pick's disease. Most research has focussed on selected patients with a specific though rare genetic vulnerability. However, these findings have been found equally important in understanding the pathogenetic principles involved in solitary, non-familial forms of dementing illness.

Finally we discuss the consequences of recent research for future development. Next to optimism we want to pay attention to the medical-ethical aspects involved in this line of research.