A ribbon diagram of apolipoprotein E. Variants of this protein influence the risk of developing<unk> . Like other synucleinopathies, the exact cause of<unk>  is unknown. No trigger for the build-up of alpha-synuclein deposits in the central nervous system has been conclusively identified. Synucleinopathies are typically caused by interactions of genetic and environmental influences; infectious causes have also been considered, but arguments in their favor are controversial and lacking in support. Most people with<unk>  do not have affected family members, although occasionally<unk>  runs in a family. The heritability of<unk>  is thought to be around 30% (that is, about 70% of traits associated with<unk>  are not inherited). There is overlap in the genetic risk factors for<unk> , Alzheimer's disease (AD), Parkinson's disease, and Parkinson's disease dementia. The APOE gene has three common variants. One, APOE ε4, is a risk factor for<unk>  and Alzheimer's disease, whereas APOE ε2 may be protective against both. Mutations in GBA, a gene for a lysosomal enzyme, are associated with both<unk>  and Parkinson's disease. Rarely, mutations in SNCA, the gene for alpha-synuclein, or LRRK2, a gene for a kinase enzyme, can cause any of<unk> , Alzheimer's disease, Parkinson's disease or Parkinson's disease dementia. This suggests some shared genetic pathology may underlie all four diseases. The greatest risk of developing<unk>  is being over the age of 50. Having REM sleep behavior disorder or Parkinson's disease confers a higher risk for developing<unk> . The risk of developing<unk>  has not been linked to any specific lifestyle factors. Risk factors for rapid conversion of RBD to a synucleinopathy include impairments in color vision or the ability to smell, mild cognitive impairment, and abnormal dopaminergic imaging.
Dementia with Lewy bodies
Parkinson's disease
Multiple system atrophy
Lewy body dementias
Subcortical dementia
Parkinson's disease dementia
Frontotemporal dementia
Vascular dementia