Colour vision defects in schizophrenia spectrum disorders: A systematic review

Area of Science:

• Neuroscience
• Ophthalmology
• Psychiatry

Background:

• Schizophrenia is a complex mental disorder with known cognitive and perceptual alterations.
• Color vision disturbances have been anecdotally reported in schizophrenia but not systematically reviewed.
• Understanding visual processing deficits may offer insights into schizophrenia pathophysiology.

Purpose of the Study:

• To systematically review and synthesize existing literature on color vision disturbances in patients with schizophrenia.
• To identify the nature and prevalence of color vision deficits in schizophrenia.
• To explore potential correlations between schizophrenia severity and color vision impairments.

Main Methods:

• A comprehensive literature search adhering to PRISMA-2020 guidelines was performed in Medline and Embase.
• Included studies involved individuals diagnosed with schizophrenia, investigated color vision, and had a comparator group.
• Seven fair-quality studies involving 695 patients were included, with quality appraised using the NIH Study Quality Assessment Tool.

Main Results:

• Patients with schizophrenia demonstrated impairments in color discrimination and recognition compared to healthy controls.
• 46.5% of the included patients (n=323) had a schizophrenia-spectrum disorder diagnosis.
• A weak correlation was observed between Positive and Negative Syndrome Scale for Schizophrenia (PANSS) scores and color vision error scores.
• Common study limitations included lack of sample size justification and blinding in all included studies.

Conclusions:

• This review provides early evidence of color vision deficits in patients with schizophrenia.
• The relationship between the severity of schizophrenia and the extent of color vision deficits remains unclear.
• Potential underlying mechanisms include retinal dopamine transmission alterations or cognitive deficits interacting with visual processing.
• Future research should involve larger studies, ocular parameter analysis, cognitive data collection, and multivariate analyses to clarify these mechanisms.