Cognition-Associated Changes in Retinal Thickness Relate to Limbic and Temporal Cortical Atrophy in Parkinson's Disease

Background:: Research links retinal changes to cognitive decline in Parkinson's disease (PD), paralleling findings in Alzheimer's, raising questions about specific cortical patterns of cognition-related retinal abnormalities in PD. Objective:: The study aimed to explore whether retinal thinning linked to cognitive decline could act as a potential biomarker for cerebral atrophy in PD. Methods:: Twenty seven patients with PD underwent cognitive and neurological assessments, along with retinal imaging using OCT and cerebral imaging using structural MRI. After identifying abnormal retinal layers associated with cognitive dysfunction through partial correlation analyses controlling for age-related effects, associations between these retinal layers and the parcellated cerebral gray matter were assessed using multiple comparison-corrected partial correlation analyses adjusted for age and gender. Results:: Significant positive correlations were found between cognitive impairment measured by MoCA and specific retinal layers (IPL, GCL, and RNFL). Of these, strong associations were observed between the IPL and GCL and cortical thickness in brain the temporal lobe and limbic cortex, with more detailed further analysis showing significant correlations particularly within the middle and posterior cingulate cortex in the limbic cortex and the middle and superior temporal gyrus in the temporal lobe. Conclusion:: Correlations between retinal thinning, cognitive decline, and specific patterns of cortical atrophy in PD support a potential of retinal measurements as a biomarker for cognitive impairment linked to cerebral neurodegeneration.