Loss of sense of smell is common in Parkinson’s but is not realised by many until they are tested; there are also people with Parkinson's whose sense of smell is unaffected, suggesting that this part of the brain is working normally. This indicates that the causes of Parkinson's and the brain pathways it affects are not the same in everyone – if we can learn more about why this is, we can develop targeted treatments. This paper looks at sense of smell in people with a rare genetic mutation in the Parkin gene to determine if everyone with this mutation maintains a normal sense of smell.

By the time a definitive Parkinson’s diagnosis is made, a lot of nerve damage has already happened as a diagnosis is usually made after motor symptoms appear. However, many people have non-motor symptoms which could be helpful in creating a screening program to identify Parkinson's earlier if a combination of these non-motor symptoms are found to precede the motor ones. If we can identify Parkinson's earlier then we would be able to get better benefit from specific preventative treatments. 

Statins are a class of drug commonly prescribed to people who have had vascular problems like stroke or heart attack.  Increasingly, they are prescribed to people who are at risk of developing vascular problems to help prevent such an event. 

We found that about half as many people with Parkinson's and high vascular risk are given statins preventatively, compared to people with Parkinson's who have already experienced stroke or heart attack.  This could be because symptoms of vascular risk like memory and walking problems are attributed to Parkinson's rather than vascular risk.

People who are at-risk of stroke and heart attack may have features like narrow blood vessels which cause memory problems and difficuly walking, just like Parkinson's. So, for people with both, it's unclear which is responsible for these problems.  We found that people with Parkinson's and an increased vascular risk had more memory and walking problems, which suggests vascular risk could be the underlying cause of these particular symptoms.

Loss of the sense of smell is common in Parkinson's, but often not realised by many until they undergo testing. Sense of smell tells us about a particular area of brain function (the olfactory bulb) which is particularly affected by Parkinson's. To be sure of the meaning and understanding of these tests, comparison to people without Parkinson's is necessary. There are a couple of problems with this which are explored here, along with ways to correct them.

Making an accurate diagnosis of Parkinson's is essential to test new treatments. Improving diagnostic accuracy can be achieved by setting strict criteria that assess a whole range of signs and symptoms – the most recent MDS criteria here were developed as a result.

A small proportion of people with Parkinson’s disease have a gene variation in an area called GBA. This variation has been suggested to cause quicker disease progression and increased memory problems. This study did not find an increase in memory problems due to GBA variation, which could suggest that current treatments in development could be preventative towards future memory loss.

This paper sets the scene and describes the study, summarising how many people with Parkinson's joined the study, how long they had Parkinson's when they joined, and a whole range of other facts and figures.