Patients with schizophrenia or bipolar disorder have retinal microvascular abnormalities when compared with healthy adults, according to a study published in Bipolar Disorders.

Researchers examined the diameters of the retinal venules and arterioles for abnormalities in patients with schizophrenia and bipolar disorder. Patients with schizophrenia or bipolar disorder were clinically evaluated, completed questionnaires to evaluate the severity of symptoms, and underwent retinal imaging to measure retinal vasculature. Healthy volunteers were also clinically evaluated and completed retinal imaging to serve as the control cohort. The arteriole diameter was calculated using the Central Retinal Artery Equivalent, and the venular diameter was calculated using the Central Retinal Vein Equivalent.

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Of the 277 participants analyzed, 98 were diagnosed with schizophrenia, 87 were diagnosed with bipolar disorder, and 92 were healthy controls. Significant differences were found between the schizophrenia cohort, the bipolar cohort, and the control cohort for mean age (mean ages of 32.7, 32.9, 30.2, respectively; P =.012) and for gender differences (men/women ratio 64/34, 54/33, 41/51, respectively; P =.009).

Significant differences were also found between the schizophrenia cohort, the bipolar cohort, and the control cohort for average venular diameter (average Central Retinal Vein Equivalent 213.4, 227.6, 196.5, respectively; P <.001) and the average arteriolar diameter (average Central Retinal Artery Equivalent 102.5, 95.8, 110.7, respectively; P <.001). When compared with healthy controls, both the schizophrenia cohort and the bipolar cohort had a wider venular diameter and narrower arteriolar diameter. When comparing the schizophrenia cohort with the bipolar cohort, the bipolar cohort had wider venular diameter and narrower arteriolar diameter than the schizophrenia cohort.

Limitations of this study included potential confounding effects of medication treatment, blood glucose levels and blood pressures not being measured before retinal images were obtained, lifestyle data not being collected, and the cross-sectional nature of this study not accounting for the length of disease progress.

The researchers concluded that their “study indicates significant differences in retinal microvascular diameters in patients with [schizophrenia] and [bipolar disorder] when compared to [healthy volunteers]; patients with [bipolar disorder] and [schizophrenia] have narrower arterioles and wider venules in comparison to [healthy volunteers], and patients with [bipolar disorder] have narrower arterioles and wider venules in comparison to [schizophrenia] patients.”

One investigator reports being a co-founder and director at Forus Health Pvt. Ltd., India.

Reference

Appaji A, Nagendra B, Chako DM, et al. Retinal vascular abnormalities in schizophrenia and bipolar disorder: a window to the brain [published online April 22, 2019]. Bipolar Disord. doi: 10.1111/bdi.12779