A method is described whereby hyaluronidase may be administered intrathecally in the aged by means of the lumbar route. The following findings are recorded: (1) The occurrence of a fleeting meningeal response; (2) a tendency to lower the blood brain barrier; (3) possible general favorable results with respect to behavior. The way seems open for the further development of this technique, especially in the direction of attempting to pass through the lowered blood brain barrier substances important for the metabolism of the aged.Abstract Teaser