Distractibility and recall capability in schizophrenics. A 4 year longitudinal study of stability in cognitive performance.

Longitudinal study is a well suited, but so far not much used, research strategy to elucidate which cognitive deficits are markers of vulnerability and which are symptom-linked states in schizophrenia. In the present study, 14 schizophrenics, eight non-psychotic psychiatric controls and 20 normals were assessed on recall performance and distractibility twice, at an interval of 4 years. The method was a digit-span test with neutral and distractor condition strings. Results showed that schizophrenics, primarily non-paranoid schizophrenics, were inferior to normals with respect to short-term recall at both instances of assessment, a finding which indicates recall deficiency to be a vulnerability-linked factor in this sub-group of schizophrenics. Paranoid schizophrenics performed better on the distractor strings than on the matched neutral strings at the first assessment, but not at the second. Non-paranoid schizophrenics, as well as the control groups, showed a relatively stable pattern of performance with respect to distractibility. How distracting stimuli are dealt with may thus be a symptom-linked factor in schizophrenia, since most of the paranoid schizophrenics changed symptomatology from the first to the second assessment. The present data cannot, however, be used to draw a definite conclusion on this point.