Because of population ageing, dementias are likely to become a major scourge of the 21st century. Causes of dementia include Alzheimer's disease, cerebrovascular disease, and lesser known entities such as frontotemporal dementia or dementia with Lewy bodies. Neuroinflammation is likely to play an important role in the pathogenesis of dementia by the killing of neurons through inflammatory mechanisms. Such a role of neuroinflammation is well documented for Alzheimer's disease, and it is likely to play a role in other types of dementia as well. Reactive oxygen species (ROS) play a key role in inflammatory tissue destruction. The phagocyte NADPH oxidase NOX2 is the best studied ROS-generating system. In the central nervous system, it is expressed in microglia and--to a lesser extent--in neurons. Indeed, there is emerging experimental evidence for a role of NOX2 in Alzheimer's and cerebrovascular disease. Recently, six novel ROS-generating NADPH oxidases with homology to NOX2 have been discovered. Several of them are also expressed in the central nervous system. In this article, we hypothesize a role of NOX-type NADPH oxidases in inflammatory neuronal loss. We review presently available evidence and suggest that NOX-type NADPH oxidases may become promising pharmacological targets for the treatment and prevention of dementia.