In This Issue

One possible agent of sunlight’s physiological effects on mood is melanopsin, a photoactive pigment in cells of the inner retina. Its absorption spectrum peaks in blue wavelengths, which have been studied in light therapy for seasonal affective disorder. Oren et al. (CME, p. 1403) also describe processes in which light stimulates tetrapyrrole pigments, including hemoglobin and bilirubin, which may act as blood-borne photoreceptors and regulate “gasotransmitters,” such as carbon monoxide and nitric oxide, when exposed to light in the eye.

Individuals who developed schizophrenia by age 38 had wider retinal venules, i.e., venous microvessels, than healthy participants in a population study in Dunedin, New Zealand. Hypertension and other conditions did not account for the difference, report Meier et al. (CME, p. 1451). Wider venules were also associated with subthreshold psychosis symptoms in the entire cohort and with childhood psychosis symptoms. Retinal and cerebral microvessels are structurally and functionally homologous, and Malaspina describes in an editorial (p. 1382) how vascular dysfunction could contribute to schizophrenia but might also signal systemic disease.