Accelerated age-related decline in processing resources in schizophrenia: Evidence from pupillary responses recorded during the span of apprehension task

Cognitive impairment in schizophrenia may be related to reduced availabilit y of information-processing resources (resource limitations hypothesis). An abnormally accelerated age-related decline in processing resource availabi lity may also occur in older patients with schizophrenia (neurodegeneration hypothesis). To test these hypotheses, pupillary responses were recorded a s an index of processing resource availibility during performance of the sp an of apprehension (SOA) task in 33 middle-aged and older patients with sch izophrenia and 37 age-comparable nonpsychiatric participants. Consistent wi th the resource-limitations hypothesis, the patients with schizophrenia sho wed impaired detection accuracy and abnormally small pupillary responses (r educed resource allocation) only in the higher processing load SOA conditio ns. This pattern of results suggests that the patients depleted their avail able processing resources at lower processing loads than the nonpsychiatric participants. Consistent with the neurodegeneration hypothesis, cross-sect ional analyses showed abnormally accelerated rates of age-related decline i n SOA performance and pupillary responses in the patients with schizophreni a relative to age-comparable normal participants.