Commonalities in the genetics of Alzheimer's disease and Parkinson's disease

Alzheimer's disease (AD) and Parkinson's disease (PD) are neurodegenerative diseases that have a tremendous impact on the lives of affected individuals. There is a great probability of developing concurrent parkinsonism in AD and vice versa than would be predicted by independent prevalence of each disease. Both diseases have genetic familial forms with a prevalence of less than 5-10%, but the majority of the cases are sporadic. Several hypotheses exist regarding the etiology of these diseases, such as oxidative stress, inflammatory processes, ubiquitin-proteasome system dysfunction, energy deficits, cell cycle deficiencies and glutamate exitotoxicities. Since diagnosis occurs in late-stage disease after neuronal loss, it decreases the opportunity for neuroprotective/neurorestorative therapies. Therefore, early and specific diagnosis is required as well as new therapy approaches for the growing burden of AD and PD.