Schizotypy and individual differences in the frequency of normal associations in verbal utterances

Recent empirical evidence [Maher, B.A., Manschreck, T.C., Linnert, J., Candela, S., 2005. Quantitative assessment of the frequency of normal associations in the utterances of schizophrenia patients and healthy controls. Schizophrenia Research 78, 219-224] shows that schizophrenia patients produce an elevated rate of normative thought associations in verbal utterances as measured by an objective computerized procedure. An important theoretical question concerns whether such an elevated rate of associative activity is due merely to psychosis, or can it be found in schizotypic subjects with no prior history of psychosis.

We hypothesized that schizotypic features should be correlated with associative performance, especially the positive symptom-like schizotypic features. The present study examined associative performance in psychometrically-identified schizotypic subjects (n=25) and normal control (n=29) subjects. We studied individual differences in schizotypal personality features in relation to the associative performance index.

Level of normative associations was correlated with total schizotypic features, particularly those involving reality distortion and disorganization. Regression analysis revealed higher levels of disorganization features and lower levels of negative schizotypal features uniquely accounted for variation in the associative performance index. Partial correlation analysis suggested that the negative schizotypic features dimension may function as a suppressor variable moderating the relationship between disorganization and level of normative associations.

Disorganization-related schizotypal features among individuals with no prior history of psychosis are correlated with elevated levels of normative associations. This relationship is most likely moderated by negative schizotypic features. These data support the presence of hyperassociative processes in those deemed to be at elevated risk for schizophrenia (or, more broadly perhaps, psychosis). Our findings support the utility of measuring associative performance using an objective measure and suggest that associative performance may be an endophenotype [Gottesman, I., Gould, T., 2003. The endophenotype concept in psychiatry: etymology and strategic intentions. American Journal of Psychiatry 160, 636-645] for schizophrenia.