Lower retinal nerve fiber layer (RNFL) thickness is associated with an increased risk for clinically relevant depressive symptoms and more depressive symptoms over time, according to study findings published in JAMA Network Open.
Neurodegeneration in various brain regions may cause multiple symptoms associated with late-life depression, including mood, cognitive, and behavioral changes. While it was suspected that neurodegeneration may contribute to depression, data on the potential association are limited.
The objective of the current study was to determine the association between lower RNFL, a marker of neurodegeneration, with clinically relevant depressive symptoms and depressive symptoms over time.
The population-based cohort study included patients from the general population in the Netherlands with baseline examination between 2010 and 2020. Using the Patient Health Questionnaire (PHQ)-9, depressive symptoms were assessed at baseline and annually overtime. The presence of clinically relevant depressive symptoms was defined as a PHQ-9 score of 10 or higher.
The study sample included 4934 individuals (mean age, 59.7 years; 50.8% women) with depressive symptoms over time. During a median follow-up of 5.0 years, 445 participants were newly diagnosed with clinically relevant depressive symptoms.
After adjustment for demographic, cardiovascular, and lifestyle factors, lower RNFL thickness was significantly associated with a higher incidence of clinically relevant depressive symptoms (per 1 SD, hazard ratio, 1.11; 95% CI, 1.01-1.23) and more depressive symptoms over time (rate ratio, 1.04; 95% CI, 1.01-1.06).
The study had several limitations, including the use of PHQ-9 for the diagnosis of major depressive disorder, unmeasured confounders, and potential underestimation of the reported association due to missing data, measurement error, or inability to account for antidepressants use started after the baseline measurement.
“The present population-based cohort study found that lower RNFL thickness was associated with a higher incidence of clinically relevant depressive symptoms and more depressive symptoms over time. Hence, neurodegeneration may contribute to the early pathobiology of late-life depression and monitoring of retinal neurodegeneration may provide a means to identify individuals at risk for late-life depression,” concluded the researchers.
van der Heide FCT, Steens ILM, Geraets AFJ, et al. Association of retinal nerve fiber layer thickness, an index of neurodegeneration, with depressive symptoms over time. JAMA Netw Open. Published online November 1, 2021. doi: 10.1001/jamanetworkopen.2021.34753