The authors interviewed 32 patients (25 with an RDC diagnosis of schizophrenia and seven with schizoaffective disorder) consecutively admitted to a psychiatric outpatient clinic. Ten patients had a history of photophilic behaviour with sun-gazing, while 20 patients showed no unusual behaviour related to light. Two patients who had depressive symptoms at the time of interview had a history of photophobic behaviour. Sixteen patients and 12 controls were tested for their threshold for discomfort of high intensity light; the thresholds were significantly higher in the patients with schizophrenia (especially in those with history of sun gazing). The implications of these findings for clinical practice and research are discussed.
Electroretinographic (ERG) measurements were performed in 9 schizophrenic patients and in 13 control subjects. The measurements of schizophrenic patients as a group did not differ from those of normals. However, 6 schizophrenic patients who had a past history of sun gazing showed a decrease in retinal responsiveness under conditions of light adaptation. These results suggest that a subgroup of schizophrenic patients, who show deviant light-related behavior, have abnormal ERG. We postulate that an abnormality in retinal dopaminergic neurons, which are known to reduce light responsiveness of horizontal and ganglion cells, is the underlying pathophysiology of this clinical finding.
The assessment of abnormal light-related behaviour is important for methodological reasons, and has a prophylactic and heuristic value. Since no operationalization of these behaviour patterns has been published until now, we constructed a questionnaire to identify abnormal light intensity preference based on a systematic study and previous case reports. We administered the questionnaire to patients with schizophrenia (n = 46) or major depression (n = 55), and to healthy control subjects (n = 70). Photophilia was more frequently diagnosed in schizophrenia than in depression (P < 0.001). Photophobia was more frequently observed in depression than in schizophrenia; however, this difference was not statistically significant. None of the healthy subjects showed these phenomena. The kappa value was 0.66 for photophilia and 0.65 for photophobia. Patients with schizophrenia had a higher mean photophilia score than depressive patients (P < 0.001) and healthy subjects (P < 0.05). Depressed patients had higher photophobia scores than schizophrenics (P < 0.05) and healthy subjects (P < 0.001). The photophilia score was positively correlated and the photophobia score was negatively correlated with the light intensity preference (measured by means of a photometer) (P < 0.001). A significant positive correlation between the photophilia score and the percentage of time spent in bright and very bright areas was observed (P < 0.05). Scores were not related to age or gender. These results represent initial data in support of the validity and reliability of our questionnaire for distinguishing between patients with and without abnormal light-exposure behaviour patterns.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.