[Genetic factors associated with dementia in Parkinson's disease (PD)]

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor and non-motor symptoms. Dementia is a frequent complication of idiopathic Parkinsonism or PD, usually occurring later in the protracted course of the illness. Some risk factors to develop dementia in PD are aging, severe Parkinson´s symptoms, rigid-akinetic form, hallucinations, and mild cognitive impairment documented at the first examinations. It is not yet clear if some genetic factors are either risk or protector for progression to dementia. In a review of the literature, we found that mutations in the alpha-synuclein gene are the most responsible for developing dementia, either from PARK1 or 4 mutations. GBA (glucocerebrosidase) is another accountable factor. However, the vast majority of patients suffer from non-Mendelian or complex forms of PD, which are likely caused by the combined effects of genetic and environmental factors. There is not until now a clear relation between some polymorphisms in candidate genes and cognitive deterioration, as many studies have not clearly identified this phenotype.