After multiple adjustments, analysis of data from more than 114,000 participants in the UK Biobank Study showed that visual impairment was linked to a 19% higher risk for depression.
In addition, imaging results showed a significant link between deteriorating brain structures and depression in those with poor visual acuity.
Dr. Ipsit Vahia
“Our findings highlight the value of visual health in association with mental health,” Xiayin Zhang, PhD, Guangdong Eye Institute, department of ophthalmology, Guangdong Provincial People’s Hospital, Guangzhou, China, and colleagues write.
“Screening of vision at an early stage should be embedded in the middle-aged and older population to stratify the vulnerable population at risk for depression,” the investigators add.
The findings were published online in JAMA Network Open.
UK biobank analyses
The analysis included 114,583 participants (54.5% women; mean age, 56.8 years) from the UK Biobank who completed standardized questionnaires and underwent ocular examinations.
To test distance visual acuity, all were asked to read letters on lines from the top to the bottom of a chart while wearing prescribed optical correction. Visual impairment was defined as visual acuity worse than 0.3 logarithm of the minimum angle of resolution (LogMAR) units.
Depressive symptoms were self-reported using the two-item Patient Health Questionnaire (PHQ-2), in which a score of 3 or more indicates depression. As well, a medical practitioner conducted an assessment of depression at baseline.
Among the participants, 87.2% had no visual impairment or depression and acted as the healthy control group. In addition, 3.2% showed visual impairment, 10% reported a diagnosis of depression, and 0.4% had both.
Researchers adjusted for age, sex, race, ethnicity, education, smoking, alcohol consumption, physical activity, family history of severe depression, obesity, hypertension, diabetes, hyperlipidemia, and deprivation on the Townsend index.
Among those with visual impairment, 12.4% had depression, compared with 9.9% without visual impairment.
Structure deterioration
After adjusting for potential confounders, visual impairment was associated with a 19% higher risk for depression (odds ratio, 1.19; 95% confidence interval, 1.05-1.34; P = .003). In addition, 1-line–worse visual acuity was associated with 5% higher odds of depression (OR, 1.05; 95% CI, 1.04-1.07; P < .001).
The association between visual acuity and depression was found in both younger (39-58 years) and older (59-72 years) groups, as well as in both men and women.
The researchers also explored the association between depressive symptoms and brain structure using MRI scans from a subset of 7,844 individuals (51% women; 2% with visual impairment).
Results showed linear associations between PHQ-2 scores and the left volume of gray matter in the supracalcarine cortex (coefficient, 7.61; 95% CI, 3.9-11.3; adjusted P = .006).
The investigators note that the supracalcarine cortex is spatially connected to the primary visual cortex, suggesting the visual cortex may be involved in the pathogenesis of depression.
PHQ-2 scores were also associated with mean isotropic volume fraction (ISOVF) in the right fornix (cres) and/or stria terminalis (coefficient, .003; 95% CI, 0.001-0.004; adjusted P = .01).
The links “could be moderated by visual acuity, whereby increased PHQ score was associated with higher ISOVF levels only among those with poorer visual acuity (P = .02 for interaction),” the investigators report.
These results “suggest that poorer visual acuity was associated with greater depressive symptoms and may have contributed to the related deterioration of the fornix and stria terminalis,” they add.
They note that previous studies have supported the hypothesis that the fornix and stria terminalis are involved in the pathophysiology of other brain-related conditions, including schizophrenia, bipolar disorder, and autism spectrum disorder.
However, the investigators did not have information on how long the participants had experienced visual impairment, so they couldn’t investigate whether results were affected by time. Additional study limitations cited were that depression may affect vision and that a large proportion of the participants (89.3%) were White.