A syndrome is described which is found in individuals who have a family history of allergic symptoms and who also have a family history of a carbohydrate-related metabolic disease. It is characterized by certain mental symptoms which appear in part to be due to the effect of unknown intermediate metabolites of certain foods—producing a subtle organic component—and often is accompanied by physical symptoms which may simulate allergy. The characteristic mental state is one consisting of motor hyperactivity, affective lability and intensity, and certain cognitive defects, with corresponding ego-control defects. There is a vulnerability to sudden regressive shifts in all functions, probably physiologically determined.