Leigh Christopher, PhD student,
Centre for Addiction and Mental Health
Graduate Student Award: $30,000 over two years

Identifying the role of amyloid deposition in cognitive decline in Parkinson’s disease

One of the mysteries about Parkinson’s disease is why some people’s memory, judgment and reasoning are affected, and why others do not experience these symptoms of cognitive impairment.

At the Centre for Addiction and Mental Health in Toronto, PhD student Leigh Christopher uses brain imaging to study protein deposits that clump together in the brain, a phenomenon called amyloid deposition. Christopher, a neuroscientist, investigates the way these clumps of protein affect the ability of different networks or circuits in the brain to connect and communicate with one another, a problem that may cause cognitive impairment and dementia.

Using Positron Emission Tomography, or PET scans, Christopher and her colleagues scan the brains of people with Parkinson’s after they have received an injection of a radioactive molecule that binds to the amyloid clumps. The scans enable the researchers to see which areas of the brains the protein clumps occupy, and to measure the amount of clumping in different brain areas.

The subjects will also receive Magnetic Resonance Imaging (MRI) scans while they are resting in a scanner, allowing the researchers to measure fluctuations in their brain activity.

“We take that information and we can see where activity in different regions of the brain correlates with one another,” says Christopher. “That shows us how connected or how functionally connected those regions are.”

If brain networks are not well connected, they can block messages and cause the circuits or networks in the brain to misfire.

Christopher and her team will compare their measurements of amyloid accumulation in brain cells and the correlation with brain regions in people with Parkinson’s against similar measurements in people without Parkinson’s disease. They believe greater amounts of amyloid in particular regions of the brain interfere with connectivity and communication among brain networks – but they need to test their theory.

Christopher hopes her work will lead to a better understanding of the changes in the brain that occur as part of a process that makes people vulnerable to cognitive decline. This basic research will set the stage for future investigations into why these protein clumps accumulate in particular brain regions, which could eventually lead to new therapies to prevent the accumulation.