NeuRA Magazine #27


Professor Caroline Rae is working on an early detection program for Parkinson’s disease to identify people most at risk. The program will also identify those in the early stages of the disease so that treatment can be introduced sooner.
An interview with Professor Rae expands on this important new approach in Parkinson’s research.

Why are you taking a different approach to Parkinson’s disease research?

The main reason is that by the time a person is diagnosed with Parkinson’s they have unfortunately lost areas of their brain which they need in order to recover. We did an initial study looking at a particular area of the brain affected by Parkinson’s disease called the substantia nigra and found that at the point they were diagnosed this part of the brain had deteriorated or died.

This is a critical area of the brain that produces a neurotransmitter called dopamine and is involved in motor control. It is eroded by this disease, and by the time a neurologist makes a diagnosis, it is too late to save this important functional part of the brain. That is why it is critical to take a different approach to identify the disease well in advance of its symptoms.

What is the substantia nigra and why is it important?

The substantia nigra forms part of the nigrostriatal circuitry which connects other parts of the brain associated with control of movement and includes nerves that use dopamine as their major chemical communicator or neurotransmitter. Parkinson’s disease targets these nerves in particular, so as they die off the brain’s ability to control movement is reduced, producing the symptoms which are a hallmark of the disease.

How does Magnetic Resonance Imaging (MRI) technology provide new insights?

We use MRI technology to study brain structure and as MRI technology is evolving it is enabling us to measure brain structure on a much finer detailed level and in more difficult and deeper parts of the brain. The substantia nigra is right down at the bottom of the brain and is an area that has not been easy to image. It is also technically challenging to track the connections from the substantia nigra to other parts of the brain. We are one of the few groups here at NeuRA who are looking at substantia nigra connections in those at higher risk of developing Parkinson’s.

We use a technique called High Angular Resolution Diffusion Imaging (HARDI) to actually look at the wiring between the substantia nigra and other parts of the brain that control movement. We have found that by the time people are diagnosed with Parkinson’s disease they have largely already lost most, if not all, of the connections from the substantia nigra to the rest of the brain.

Why is it important to catch Parkinson’s disease 10-15 years in advance?

We are studying a group of people whose substantia nigra has a feature that makes it give a larger than usual signal in response to a pulse of ultrasound delivered by placing an ultrasound probe over a particular place on the skull. It has been shown by a group in Germany that people with this feature are seventeen times more likely to go on to develop Parkinson’s. In our initial MRI study of these people, we have found that they have already lost up to 60 per cent of the connections between the substantia nigra and the rest of the brain. A neurologist, doing normal clinical checks, will rate these people as healthy. However, if we put very sensitive accelerometers on the fingers of these people while they are doing small tasks with their hands, like lifting an object, we can find subtle signs of motor impairment.

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