Dietary and metabolic effects on rhesus social behavior: Phenylalanine‐related dietary alterations

Abstract

Infant rhesus monkeys were (a) fed a diet high in phenylalanine or (b) fed a diet high in p-chlorophenylalanine for the 1st 12 months of life, (c) selected from mothers fed a diet high in phenylalanine during pregnancy, (d) fed a diet low in phenylalanine, (e) maintained as controls, or (f) maintained as pair-fed controls. Tested during the 1st year of life with familiar peers, during the 2nd year with unfamiliar stimulus animals and with a movie film, the 3 groups of phenylketonuric monkeys showed less play and other positive social behavior and more withdrawal and more aggressive behavior than did the 2 control groups. The results support learning data suggesting that phenylketonuric monkeys are more emotionally reactive.

PKU, Learning, and models of mental retardation

“…Since neither the postnatal nor the fetal PKU group showed impaired performance during the initial trials when no delay was used, it is clear that place discrimination is not impaired, but that it is the delay itself which impedes performance. Although it is difficult to know how to interpret this inability to cope with a delay, the authors themselves suggest that the impaired performance, when the delay is used, leads to a "high level of emotional responses" in the postnatal group, an interpretation whch is entirely consistent with the behavioral differences observed in these monkeys (Chamove, 1980;Chamove, Waisman, & Harlow, 1970).…”

Dietary effects on rhesus social behavior: Altered amino acid diets

“…The tyrosine and alanine groups showed considerable social play, whereas the histidine group was low in nonsocial play. The results of the normally sensitive stimulus test (Chamove, 1980a), as can be seen in Fig. 2, were again quite uniform across groups.…”

“…1). However, none of the groups showed the characteristic significantly high levels of aggression and withdrawal and low levels of play and other positive behaviors seen in monkeys with induced phenylketonuria (Chamove, 1980a) or the altered levels of aggression in induced-protein-or protein-calorie undernutrition (Chamove, 1980b).…”

“…Whether the behaviors were directed toward another animal or not, and if the animals were in contact or not, was also noted. True durations of these behaviors were recorded using focd animal sampling and clocks (detailed in Chamove, 1980a).…”

“…The data for another four monkeys, the control-pf group, are included here also. These animals were one group of controls for a related study (Chamove, 1980a) using phenylalanine, and they were pair-fed according to the intake of a group of monkeys on a high-phenylalanine diet. They are presented here (a) to increase the comparison control data and (b) because the tryptophan diet, like the phenylalanine diet, was bitter-tasting and consumed at a different and reduced rate from the others.…”