The complaints of 400 patients who were sent by their general practitioners to our hospital are enumerated in table 1 according to thier frequency (33 items). Three groups of complaints stand out: a) disturbances of memory and concentration b) nervousness - inward restlessness - increased irritability c) fatigue - decrease of performance. In the earlier literature similar syndromes were described as signs of the diminution of cerebral performance. If they appeared in old persons they were considered as an expression of a (physio-logical?) decrease of neurons. In middle-aged men the same syndrome was considered as sign of a premature cerebral arteriosclerosis. Recent investigations have shown that a decrease of cerebral performance is often due to a degenerative process of Alzheimer's type. In many cases it is difficult to decide concerning which of the three basic processes we have to take into consideration if a diminution in cerebral performance occurs. Presented are: Cues for diagnosis, differential diagnosis and treatment of the syndrome often seen in general practice today.