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Following up on their previous work of four years ago, Albert, Hoch and Waelsch repeat their studies of the effect of glutamic acid on mental deficiency, this time on a much larger group of subjects. About three hundred patients were screened of which one hundred forty-eight were chosen as suitable and placed on medication. Of these, less than seventy completed the full cycle of the study; fifty of these were in the lower I. Q. group. A placebo and glutamic acid were alternately administered to each subject, so that each acted as his own control. The dosage was ten to twelve grams of the L-glutamic acid daily.
The results, which were carefully studied statistically, showed a significant increase in I. Q. following administration of the drug in cases falling into the lower I. Q. range (twenty-two to sixty, Binet Form M). The increase, though unequivocal, was generally too small to be of practical or clinical importance. In general, mental defectives of the secondary type responded better than those of the primary type. It is suggested that since the anlage of the nervous system is normal in the secondary cases, the healthy parts of it are perhaps able to take over, especially under the influence of glutamic acid. It is also possible that glutamic acid brings about its beneficial effect by acting as a general stimulating agent and by eliminating certain emotional factors which interfere with intellectual performance. Other studies which have used the salts instead of the free amino acid have failed to duplicate these beneficial results. In the high I. Q. group, external factors interfered with the reliability of the findings.