Association between the LRP1B and APOE loci and the development of Parkinson’s disease dementia

Abstract Parkinson’s disease is one of the most common age-related neurodegenerative disorders. Although predominantly a motor disorder, cognitive impairment and dementia are important features of Parkinson’s disease, particularly in the later stages of the disease. However, the rate of cognitive decline varies among Parkinson’s disease patients, and the genetic basis for this heterogeneity is incompletely understood. To explore the genetic factors associated with rate of progression to Parkinson’s disease dementia, we performed a genome-wide survival meta-analysis of 3923 clinically diagnosed Parkinson’s disease cases of European ancestry from four longitudinal cohorts. In total, 6.7% of individuals with Parkinson’s disease developed dementia during study follow-up, on average 4.4 ± 2.4 years from disease diagnosis. We have identified the APOE ε4 allele as a major risk factor for the conversion to Parkinson’s disease dementia [hazard ratio = 2.41 (1.94–3.00), P = 2.32 × 10−15], as well as a new locus within the ApoE and APP receptor LRP1B gene [hazard ratio = 3.23 (2.17–4.81), P = 7.07 × 10−09]. In a candidate gene analysis, GBA variants were also identified to be associated with higher risk of progression to dementia [hazard ratio = 2.02 (1.21–3.32), P = 0.007]. CSF biomarker analysis also implicated the amyloid pathway in Parkinson’s disease dementia, with significantly reduced levels of amyloid β42 (P = 0.0012) in Parkinson’s disease dementia compared to Parkinson’s disease without dementia. These results identify a new candidate gene associated with faster conversion to dementia in Parkinson's disease and suggest that amyloid-targeting therapy may have a role in preventing Parkinson’s disease dementia. The genetic factors that influence cognitive outcomes in Parkinson’s disease have yet to be fully determined. Real et al. perform a genome-wide survival study in almost 4000 patients and identify new genetic loci associated with faster progression to Parkinson’s disease dementia, including the LRP1B receptor.