Bridges between schizophrenia and gerontology: Generalized or specific deficits?

Abstract

A well-documented fact is that when schizophrenics are compared with normals or when the old are compared with the young, a decrement in performance, commonly termed psychological deficit, typically results. Not as well documented is the striking similarity between schizophrenics and the elderly in their performance on laboratory tasks. The purposes of the present discussion are (a) to document the similarity between old and schizophrenic subjects in their laboratory performance, (b) to show how this similarity may provide a tool with which to reevaluate psychological-deficit theories of schizophrenia, and (c) to provide one possible unifying explanation for the similarity between schizophrenic and old subjects.For the past 40 years the primary approach taken by psychologists to study the nature of schizophrenia has been to compare the performance of schizophrenics, or various subgroups of schizophrenics, with the performance of normals on an endless variety of tasks. This psychological-deficit approach climaxed in the 1960s with reviews of the literature that attempted to relate the decrements in performance shown by schizophrenics on a variety of different, seemingly unrelated, tasks to a single underlying deficit (e.g., Lang & Buss, 1965;Payne, 1966;Venables, 1964;Yates, 1966). Theoretically, these deficit theories related the decrement in performance shown by schizophrenics to a psychological function (e.g., attention) that was believed to be related to the cause of schizophrenia. The present difficulty with the psychological-deficit approach is that schizophrenics show a deficit almost no matter what task is used. This has resulted in a plethora of explanatory hypotheses of the schizophrenic deficit, with no way of judging the validity of one deficit theory over another.Just as well documented as the decrement in performance shown by schizophrenics when compared with normals is the decrement in performance shown by the old when compared with the young. Although the psychological Requests for reprints should be sent to

Pupillary responses and attentional allocation problems on the backward masking task in schizophrenia

“…competition for and allocation of higher cortical stimulus identification resources) can better account for deficits. This is an old controversy about peripheral vs. more central deficits in schizophrenia research, which may be a meaningless distinction (Saccuzzo, 1977). For example, from the bottom-up, the magnocellular (transient) pathway helps orient attention toward salient stimuli, so overactive transient channel activity may be one mechanism by which a second input orients processing resources away from sustained processing of earlier relevant inputs (Butler et al, 2001(Butler et al, , 2002.…”

Age differences in symbol-digit substitution task performance

“…The slope effect in the present study may be related to a declining ability to perceptually organize visual arrays. Saccuzzo (1977) has noted that there is a good deal of similarity.in the perceptualcognitive deficits exhibited by schizophrenics and the elderly. This observation now can be extended to the Symbol Digit Substitution task (Royer, Gilmore, & Gruhn, 1981).…”

Global capacity reduction and schizophrenia

“…The emphasis has been on delineating not only a deficit as specific to schizophrenia as the manifestation of thought disorder has been seen to be, but also to define precisely the particular dysfunctional processing stage which might account for the relatively poor performance of the psychotic patient. However, the evidence for a cognitive deficit unique to schizophrenia is relatively weak (Hemsley & Zawada, 1976;Saccuzzo, 1977) and the postulated specific deficit has been located at varying stages in the processing chain by different theorists. Shakow (1972 a) defined the problem as being one of maintaining an adequate and consistent level of arousal prior to the onset of the relevant stimulus display.…”