Association of visual impairment with risk for future Parkinson's disease

BACKGROUND: Although visual dysfunction is one of the most common non-motor symptoms among patients with Parkinson's disease (PD), it is not known whether visual impairment (VI) predates the onset of clinical PD. Therefore, we aim to examine the association of VI with the future development of PD in the UK Biobank Study. METHODS: The UK Biobank Study is one of the largest cohort studies of health, enrolling over 500,000 participants aged 40–69 years between 2006 and 2010 across the UK. VI was defined as a habitual distance visual acuity (VA) worse than 0·3 logarithm of the minimum angle of resolution (LogMAR) in the better-seeing eye. Incident cases of PD were determined by self report data, hospital admission records or death records, whichever came first. Multivariable Cox proportional hazard regression models were used to investigate the association between VI and the risk of incident PD. FINDINGS: A total of 117,050 participants were free of PD at the baseline assessment. During the median observation period of 5·96 (IQR: 5·77–6·23) years, PD occurred in 222 (0·19%) participants. Visually impaired participants were at a higher risk of developing PD than non-VI participants (p < 0·001). Compared with the non-VI group, the adjusted hazard ratio was 2·28 (95% CI 1·29–4·05, p = 0·005) in the VI group. These results were consistent in the sensitivity analysis, where incident PD cases diagnosed within one year after the baseline assessment were excluded. INTERPRETATION: This cohort study found that VI was associated with an increased risk of incident PD, suggesting that VI may serve as a modifiable risk factor for prevention of future PD.