Recently, two research groups independently published journal articles suggesting that a genetic variation associated with Alzheimer's might also have an important influence in Parkinson's and related conditions. The scientists found that a protein called Apolipoprotein E (or ApoE) can affect the severity of the toxic accumulation of alpha synuclein protein in the Parkinsonian brain – a well-known trait of Parkinson's .

 ApoE is a protein that is involved in the transportation of various important molecules such as fats within cells and the bloodstream. Tiny genetic differences in our DNA have led to humans having variations of the ApoE protein - the most common variations of the protein are ApoE2, ApoE3 and ApoE4. They are all the same protein, but with small variations that can affect the function. And one of these variation in particular, Aope4, appears to be linked to an increased risk of developing Alzheimer's, compared with people carrying the ApoE3 or ApoE2 versions.

Researchers have also been investigating whether the version of ApoE a person carries influences the nature of their Parkinson's. Two research groups independently found that mice which had been genetically changed in the lab to produce high levels of alpha synuclein in their brains and also carry the ApoE4 protein version, then had a greater level of toxic accumulation of alpha-synuclein protein in their brains.

Interestingly, the researchers also looked in humans and reported that individuals with Parkinson's who carry the ApoE4 protein version, scored worse in their cognitive assessments, and in turn had higher levels of protein aggregation when their brains were examined after the patients had died.

These new findings could have important implications for future clinical trials and, importantly, may also suggest that some of the experimental therapeutics targeting ApoE4 that are currently being developed for Alzheimer’s could be useful for affected members of the Parkinson's community.

Read more about this research published in Science Translational Medicine