The reactivity of the iris muscles as an index of autonomic dysfunction in schizophrenic remission

Blunted pupil light reflex is associated with negative symptoms and working memory in individuals with schizophrenia

Two largely separate lines of research have documented altered pupillary dynamics in individuals diagnosed with schizophrenia. An older set of studies has demonstrated reductions in the pupillary light reflex (PLR) in individuals with schizophrenia; however, clinical and cognitive correlates of this blunted PLR have been relatively unexplored. More recently, a large body of work has demonstrated reductions in pupillary dilation in response to cognitive demands in individuals with schizophrenia, and the degree of this blunted pupil dilation has been related to more severe cognitive deficits and motivational negative symptoms. These clinically relevant alterations in the cognitive modulation of pupil size have been interpreted as reflecting insufficient information processing resources or inappropriate effort allocation. To begin to bridge these two lines of work, we investigated the PLR in 34 individuals with schizophrenia and 30 healthy controls and related the amplitude of the PLR to motivational negative symptoms and cognitive performance. Consistent with prior work, we found that the PLR was reduced in individuals with schizophrenia, and furthermore, that these measurements were highly reliable across individuals. Blunted constriction was associated with more severe motivational negative symptoms and poorer working memory among individuals with schizophrenia. These observed correlates provide a bridge between older literature documenting an altered PLR and more recent work reporting associations between negative symptoms, cognition, and blunted pupillary dilation in response to cognitive demands in individuals with schizophrenia. We provide possible mechanistic interpretations of our data and consider a parsimonious explanation for reduced cognitive- and light-related modulation of pupil size.

Pupillary constriction during haloperidol treatment as a predictor of relapse following drug withdrawal in schizophrenic patients

It has been proposed that the autonomic nervous system is dysregulated in schizophrenia. We hypothesized that measures of autonomic function, even during neuroleptic stabilization, might predict relapse following withdrawal of medication. Previously, shorter latencies to maximum pupillary constriction have been reported to differentiate acutely hospitalized schizophrenic patients from control subjects. Pupillary light reactions were recorded weekly from 19 chronic schizophrenic inpatients who were initially maintained on haloperidol and subsequently were withdrawn from medication under double-blind, placebo-controlled conditions. Patients were then classified as either relapsed or nonrelapsed (clinically stable) during the drug-free period. During the treatment phase, a shorter latency to maximum pupillary constriction significantly distinguished patients who were later to relapse from the nonrelapsers. The potential use of autonomic activity as an indicator of prodromal sensitivity was supported. In addition, these findings emphasize the need for classification of drug-free patients according to clinical status.

Eye movement research with schizophrenic patients and normal controls using corneal reflection-pupil center measurement

The eye movements of 20 partially remitted outpatient schizophrenics (ICD 9), for the most part receiving neuroleptic maintenance medication, and 20 normal controls were recorded using corneal reflection-pupil center measurement. Performance was investigated on the basis of widely varied measurement parameters during a fixation task and a visual search task (list of letters). Psychopathological data were additionally recorded for the group of patients by means of self and observer ratings, current social adjustment, and neuroleptic dosage. The schizophrenic patients showed the tendency to perform more poorly than the normal controls in the eye movement parameters recorded, and there was marked variation in performance within the group of schizophrenic patients. In particular, various abnormalities in fixation performance were connected differentially with individual psychopathological syndromes and neuroleptic dosage. Connections between fixation performance and search performance were found only within the group of patients. They are interpreted as an indicator of disturbed interhemispheric coordination in schizophrenics. Based upon specific pupillary findings one concludes that the processing load imposed on the attentional system by the search task is different for various schizophrenic subgroups.