Cognitive impairment in Parkinson's disease

In a new article ( Murueta‐Goyena, A., Del Pino, R., Galdós, et al. (2020), Retinal thickness predicts the risk of cognitive decline in Parkinson's disease. Ann Neurol doi:10.1002/ana.25944) the researchers analyzed longitudinal changes of retinal thickness and their predictive value as biomarkers of disease progression in idiopathic Parkinson's disease (iPD).

Macular ganglion‐inner plexiform layer complex (GCIPL) thickness in the parafoveal region (1‐ to 3‐mm ring) presented the largest reduction rate. The annualized atrophy rate was 0.63 μm in iPD patients and 0.23 μm in controls (p<0.0001). iPD patients with lower parafoveal GCIPL and peripapillary retinal nerve fiber layer (pRNFL) thickness at baseline presented an increased risk of cognitive decline at 3 years (RR 3.49, 95% CI 1.10 - 11.1, p=0.03 and RR 3.28, 95% CI 1.03 - 10.45, p=0.045, respectively). They did not identify significant associations between retinal thickness and motor deterioration.

These results provide evidence of the potential use of OCT‐measured parafoveal GCIPL thickness to monitor neurodegeneration and to predict the risk of cognitive worsening over time in iPD.