A method is provided that includes disposing midplane treatment electrodes over a superior sagittal sinus, outside and in electrical contact with a skull of a head of a subject identified as at risk of or suffering from Alzheimer's disease. Lateral treatment electrodes are disposed between 1 and 12 cm of a sagittal midplane of the skull. The subject is treated by electroosmotically driving fluid from a subarachnoid space to the superior sagittal sinus, by activating control circuitry to apply one or more treatment currents between (a) one or more of the midplane treatment electrodes and (b) one or sore of the lateral treatment electrodes. Other embodiments are also described. Other embodiments are also described.
