Alzheimer's and Parkinson's diseases are different neurodegenerative conditions that can sometimes affect the same person, which has led scientists to investigate possible links between the two. Now one team, reporting in the journal ACS Chemical Neuroscience, has identified how amyloid beta, the protein fragment strongly associated with Alzheimer's disease, can induce cellular changes that might lead to Parkinson's.

Scientists still don't fully understand what causes these neurodegenerative conditions, but their investigations have revealed some insights. For example, certain molecular changes have emerged as factors in the development of these disorders. One such change is the mutation of an enzyme called protein disulfide isomerase (PDI) that protects neurons. And some research has hinted that biomarkers related to one disease can spur molecular processes leading to others. Mahesh Narayan and colleagues wanted to see how a particular form of amyloid beta might trigger cellular changes that can induce Parkinson's disease.

In their lab, the researchers incubated certain amyloid beta fragments -- referred to as Aβ (25-35) -- with cells (known as SH-SY5Y) often used in Parkinson's research. This set off in the cells a cascade of molecular changes associated with Parkinson's, including chemical mutations to PDI and the formation of protein clumps known as Lewy bodies. The results could provide an explanation for how someone with Alzheimer's might also develop Parkinson's. The findings also could help researchers discover ways to prevent this from happening.