Apparatus is provided that includes midplane treatment electrodes, configured to be disposed 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； and lateral treatment electrodes, configured to be disposed between 1 and 12 cm of a sagittal midplane of the skull. Control circuitry is configured to treat the subject by electroosmotically driving fluid from a subarachnoid space to the superior sagittal sinus, by applying one or more treatment currents between (a) one or more of the midplane treatment electrodes and (b) one or more of the lateral treatment electrodes.
