The manifestations of the chronic brain syndrome associated with cerebral arteriosclerosis are notoriously diverse, ranging from disturbance of cerebral functions which can be recognized by physical examination to those which can be identified by examination of the patient's mental state. With widespread arteriosclerotic involvement of the cerebral circulation there are important alterations in the individual's thinking and behaviour. There is disturbance of memory, accompanied by disorientation, at first in time and place and later as to person; and intellectual functions including comprehension, problem solving, learning, and judgement are also impaired.