These studies indicate that vitamin B complex restriction caused severe primary mental changes or aggravation of pre-existing psychotic trends among the psychotic subjects.The character of the mental changes appeared to depend on speed and severity of the deprivation.Patients whose B complex intake was so restricted that it contained 400 mcg. of thiamine and correspondingly small intake of other B complex factors showed diminution of psychomotor activity, dulling of affect, loss of interests and ambitions.In some of the severely depleted patients whose thiamine intake was restricted to 200 mcg. daily, serious emotional disturbances with loss of inhibitory control developed. In others, pre-existing affective trends such as hypomanic and mildly depressive features became markedly exaggerated. The formation of paranoid trends also was observed.Among the group moderately deprived of vitamin B complex the mental changes developed slowly in the course of 3 years. However, among the subjects severely deprived of vitamin B complex, mental disturbances manifested themselves explosively, acutely, or subacutely, after only a few months of depletion.Recovery with a return to the level of pre-experimental behavior following resumption of vitamin B administration took place in days to months. It was in general rather slow in mildly restricted patients and dramatic and sudden in severely restricted patients.In our study it appeared that mild vitamin B complex restriction permitted the individual to adapt himself to the change without much distress. It was clear, however, that severe depletion accompanied by severe metabolic impairment and structural damage led to severe emotional discharges. No claim can be made that the changes observed among the subjects of our experiment are specific. A variety of factors associated with impairment of brain metabolism and changes of nervous structure are known to lead to similar mental syndromes.Abstract Teaser