The association between eye-tracking dysfunctions and thought disorder in psychosis.

The relationship between the presence of smooth-pursuit eye-movement dysfunctions and degree of thought disorder was assessed in four groups: schizophrenics, manics, atypical psychotic patients, and normal persons. A positive relationship, constant for all groups, was found to be significant but low. Impaired eye tracking accounted for 4.22% of the total variance of thought disorder. Diagnosis accounted for over 10% of the thought-disorder variance. Although there is a tendency for those persons with poor eye tracking to have higher amounts of thought disorder than those with unimpaired eye tracking, all psychotic patients, regardless of diagnostic class, tended to have thought disorder scores in the pathological range, as measured by the Thought Disorder Index. Although the data may be viewed as supporting similar hypothetical processes that underlie pursuit dysfunctions and thought disorder, the greater likelihood exists that the coupling of thought disorder and eye-tracking dysfunctions may be explained differently in the schizophrenia and in the major affective disorders.

Thought disorder in the relatives of psychotic patients.

Using the Holzman-Johnston Thought Disorder Index, thought disorder was examined in the first-degree relatives of schizophrenic, manic, and schizoaffective patients. In all three groups, there was a tendency for probands with higher thought disorder to have first-degree relatives with higher thought disorder. Furthermore, the quality of thought disorder in the groups of relatives was similar to that in the groups of probands, although it was clear that the relatives of schizoaffective-manic patients showed the highest amount of thought disorder, which was not found in the proband sample. Although based on a small sample, these findings suggest that amount and type of thought disorder differ not only among medicated patient groups but also among their unmedicated relatives.

A new look at reaction time in schizophrenia.

Schizophrenia patients demonstrate impaired manual reaction time (RT), but not saccadic RT, when given traditional tasks. To determine whether the manual RT time impairment could be eliminated by providing imperative stimuli to the finger (thus providing stimulus-response compatibility), we tested 28 chronic schizophrenic patients on finger-lift RT to visual (VIS), tactile plus visual (TAC+VIS), and auditory plus tactile plus visual (AUD+TAC+VIS) stimuli. The patients (a) were significantly slower than controls (n=28) in all three tasks, (b) showed bimodality, with 43% of patients having means and variances nearly identical to control values, and (c) had RTs significantly closer to control values in the TAC+VIS and AUD+TAC+VIS tasks than in the VIS task. The inability to normalize finger-lift RT in schizophrenia represents a genuine slowing of this response system regardless of stimulus-response compatibility. We consider other possible explanations for the differences between manual and saccadic RT, including the notion that excess processing capacity for saccadic RT may be masking possible deficits in that system.