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With degenerative brain disorders such as Parkinson’s disease often in the spotlight and September marking Alzheimer’s awareness month, it is important to note that the carers and relatives of those suffering from such disorders often have specific questions such as: ‘what happens in the human brain to result in this disease?’ ‘why isn’t there a cure or better drugs?’ or ‘what can I do to support someone with this disease?’

Stop anyone in the street and they are likely to have heard of Parkinson’s disease and may even know one of the approximately 130,000 people in the UK who has the disease. Most of these people could give a general description of what a person with Parkinson’s looks like and may know that it has something to do with the brain. Since the 1920s, we have known that Parkinson’s results from the degeneration of a very small part of the brain called the Substantia Nigra pars compacta. Although small, it connects with many regions of the brain, including some that are necessary for movement, so loss of the cells in this area have widespread consequences.

An obvious question to ask is ‘why do these neurons (cells) degenerate in some people?’ The answer to this question is complex but research suggests that, for most people, it is a combination of various factors that they have encountered in their lifetime and the interaction that these have with the person’s genetic make-up. However, because we don’t understand this in detail we currently have no way of preventing these cells from degenerating so we have attempted to replace their function. One way to do this is by using drugs and this is the basis of the action of currently used drugs, such as levodopa. Another way would be to replace the degenerated cells. Although there has been research done into achieving this, the results so far have been variable, and whilst there are a significant number of challenges to overcome before this could be considered as a standard approach to Parkinson’s disease, it remains a future prospect.

Even though we have neither a prevention nor a cure, studying Parkinson’s disease can help us better understand the consequences of the neurodegeneration so that drugs can be optimised and non-drug approaches can be used to minimise its impact. From the earliest descriptions of Parkinson’s, the emphasis has been on movement problems. Even today, the focus of therapies revolves around improving movement using drugs or other approaches such as music therapy and physiotherapy.

However, the signs and symptoms of Parkinson’s are more broad-ranging, suggesting that it is actually more complex and may involve neurodegeneration in many parts of the brain and beyond. For example, many with Parkinson’s report a change in their mood, including depression-like aspects. It would be easy to dismiss this as a reaction to having a chronic illness but evidence suggests that mood changes may be a direct consequence of neurodegeneration and may be improved by drug and music therapies.

Two other symptoms recently attributed to Parkinson’s disease pathology are a reduction in the sense of smell and reduced bowel activity leading to constipation. This might go some way to explaining why many with Parkinson’s report reduced appetite. Interestingly, these two features often pre-date the usual movement problems. Some carers feel that appreciating the broader range of symptoms associated with Parkinson’s disease has helped them to be more supportive and understanding of those they care for.

In summary, as we come to better understand the causes and consequences of neurodegeneration in Parkinson’s, we can move closer to identifying preventions or cures. In the meantime, we can use the information gathered to optimise drug and non-drug approaches to maximise the quality of life for those with the disease.

Dr Alison Cooper
Senior Lecturer in Neuroscience and Pharmacology, University of Birmingham