Retinal Biomarkers as Indicators for Cognitive Impairment and Depression

Abstract: Background/Significance: The eye is a seldom discussed organ in Consultation-Liaison (C-L) Psychiatry due to limited understanding of the overlap between ophthalmologic and psychiatric diseases. Increasingly, studies are focusing on the retina, an extension of the central nervous system (CNS), to examine the relationship between neuroophthalmological function and neuropsychiatric disorders (Silverstein, 2020). Here, we present a preliminary data analysis from an ongoing study that examines the degree of relationship between retinal biomarkers and neuropsychiatric symptoms.

Methods: We analyzed data from a current study examining retinal biomarkers of cognitive function, cerebral blood flow, and psychiatric symptoms in patients with advanced heart failure (HF). The cohort included in this preliminary cross-sectional data analysis are from the two control groups of adults with HF or with non-proliferative diabetic retinopathy (NPDR). Exclusion criteria include history of delirium, stroke, or neurocognitive disorder. We used Spearman rho correlations to determine the association between Montreal Cognitive Assessment (MoCA), Beck Depression Inventory (BDI)-7, and Generalized Anxiety Disorder (GAD)-7 scores, and measurements from retinal exams using optical coherence tomography (OCT) and electroretinography (ERG).

Results: The analysis included 19 subjects with average age of 62.9 years that included 4 females, and people with a history of depression (n=6), anxiety (n=3), or PTSD (n=1). Mean assessment scores were: GAD-7 (5.44±6.82), BDI-7 (3.0±3.27), MoCA (24.5±3.63). Significant correlations between MoCA total scores, BDI-7 total score, OCT measurement, and ERG measurement were observed. For ERG findings, there were significant correlations found between total MoCA score and photopic negative response (PhNR) amplitude (right eye: Spearman ρ = -0.67, p = 0.002; left eye: Spearman ρ = -0.57, p = 0.013), and with flicker amplitude (right eye: Spearman ρ = 0.577 p = 0.015). Significant correlations were also observed between OCT findings (macula central subfield thickness (CST)) and total BDI score (right eye: Spearman ρ = -0.49, p = 0.039; left eye Spearman ρ = -0.506, p = 0.038).

Discussion: Lower MoCA scores, indicating impaired cognition, are associated with attenuated activity in inner retinal neurons. Additionally, higher BDI scores, indicating increased severity of depression symptoms, are associated with evidence of retinal neurite and/or neural degeneration at the macula. These findings are consistent with studies that have demonstrated associations between cognitive impairment and smaller ERG amplitudes (DeBuc, 2018).

Conclusion/Implications: The findings of this ongoing study provide evidence that changes within the retina are informative regarding aspects of brain function (i.e. mood, cognition). C-L psychiatrists should consider using these brief, inexpensive, and non-invasive retinal screening and monitoring tools in patients with conditions where serious changes in brain function are likely. At the time of the ACLP conference we will have an expanded data set analysis.

References

Silverstein et al. 2020: doi.org/10.1016/j.bionps.2020.100018

DeBuc et al. 2018: doi.org/10.3389/fphys.2018.01721