Plasma free and total tryptophan, blood serotonin, and the hyperactivity syndrome: no evidence for the serotonin deficiency hypothesis.

Total and free plasma tryptophan and plasma cortisol levels were determined for children diagnosed as hyperactive or learning disabled and in normal siblings of these subjects. No differences were observed among the groups on any of the dependent variables related to a number of parameters measured for the hyperactive children such as degree of hyperactivity, presence of food allergies, favorable response to methylphenidate, and brain dysfunction. Moreover, in further comparisons no differences were found between hyperactive and age-matched controls on these variables as well as blood serotonin, nor were any differences found for a group of hyperactive children between placebo and methylphenidate trials. These data do not support earlier suggestions of a serotonin deficiency in hyperactive children.

Neuropsychological variables and mental retardation.

Improved measures of adaptive behavior would be greatly helpful in the diagnosis of mental retardation. This article describes an objective measure of adaptive behavior that has the further advantage of having a theoretical basis.

Neuropsychological changes following carotid endarterectomy.

Fifty-five subjects undergoing carotid endarterectomy were grouped according to side of operation, i.e. right, left and bilateral. There subjects were administered a comprehensive neuropsychological battery prior to and six months following surgery. The performance of these subjects was compared with a control group undergoing surgical procedures that did not involve the brain or cerebral vasculature, and a second control group composed of patients with cerebrovascular symptoms who were not operated. It was found that as a group the endarterectomy subjects improved on a greater percentage of measures. When various subgroups were examined, it was found that the right operated stroke patients improved on significantly more measures than any other group. The difference between right and left stroke patients was significant, but there was no difference between right and left TIA patients in the extent of improvement. These findings were discussed in terms of possible underlying mechanisms.

Evidence for an independent syndrome of hyperactivity.

It has recently been suggested that hyperactivity and an aggressive conduct disorder cannot exist independently in children. The results of a factor analysis of the Conners Teacher Rating Scales of over 9000 children provided preliminary evidence to the contrary; a hyperactivity factor emerged as explaining the greatest proportion of the variance. Because of the large size of our data-set, it was deemed necessary to investigate the heuristic value of this finding. Using norms calculated on composite factor scores, a contingency analysis was performed to determine the proportions of children who were above a two-standard deviation criterion of deviance on all factors and combinations of factors. The use of different degrees of statistical control produced prevalence estimates comparable to those reported in the literature. These findings raise the possibility that studies reporting different prevalences of hyperactivity may, in fact, be exercising different degrees of conservatism in classification. Also, when the extent of overlap along each of our factor dimensions was examined, a group of children who appeared to be hyperactive but not conduct-disordered emerged. These findings provide evidence for an independent syndrome of hyperactivity in a sample of Canadian children.