Pyritinol hydrochloride and cognitive functions: influence on children in slow learner classes.

Pyritinol-HCl was tested for its impact on the cognitive functions of children with learning disabilities. This study is a contribution to scientific discussion on the complicated methodologic problems in evaluating the clinical efficacy of psychopharmacologic agents. Sixty-seven pupils of slow learner classes between the ages of 11 and 16 years were treated for 6 months with 300 mg pyritinol-HCl/24 hr or placebo under strict double-blind conditions. Drug intake was stimulated and controlled by means of intense psychosocial interaction with the mothers of the subjects. The dependence variables used to test medication effects were 22 parameters of cognitive performance measured in psychologic tests for perceptual and intellectual functions which were administered immediately before and after the medication phase. First the gainscores before and after treatment with pyritinol or placebo within the 22 cognitive parameters were statistically compared. In addition, an analysis of covariance on the corrected results of the second test (treating the results of first testing as covariates) and a two group discriminant analysis for overall differences were performed. None of the 22 parameters showed statistically significant treatment effects with respect to average performance (t (pyritinol - placebo) = 1.96 to 1.31), neither could the two groups be separated by discriminant analysis (Hotelling's T2 = 35.4, df - 22 and 43, P = 0.465). With respect to a variability of gainscores, however, in four parameters there was a significantly higher variance in the pyritinol group (F = 1.85-2.33, P less than 0.05, less than 0.02, respectively). This fact may signify that pyritinol-HCl had different effects on different subjects. By means of prognostic stratification we therefore attempted to define objective criteria for a selection of subjects with probable positive treatment effects. None of the 15 tested criteria, such as body weight, age, perceptual handicaps, or reduced short term memory, IQ range, proved, however, to be critical for a prognosis of pyritinol effects within the present test population.