Cognitive imagery

Until about a decade ago, tremor and other motor impairments were considered the biggest burden of Parkinson's disease. In recent years, however, many scientists and clinicians have come to recognise cognitive difficulties, such as dementia, as being more debilitating.

Dr Tracy Melzer, of the University of Otago, Christchurch (UOC), is ahead of the pack in understanding and studying cognitive impairments. He and his colleagues from the New Zealand Brain Research Institute (NZBRI) already have almost six years of data, taken at two-year intervals from 130 Parkinson's disease patients, as well as 50 healthy volunteers.

Using the latest technology, they are collecting brain-imaging scans, comparing them with measures of disease severity and detailed cognitive tests to look for changes that might indicate the onset of dementia.

The ultimate aim is to be able to predict which patients are at the highest risk of developing cognitive impairments in the near future.

The Health Research Council recently recognised the significance of Melzer's work by awarding him one of its 2014 Emerging Researcher First Grants.

Parkinson's disease is typically a disease of the elderly so, with an ageing population, its incidence will increase. Melzer says there are drugs that can do a “relatively good job” of controlling motor issues, but nothing that really treats cognitive problems.

“If we know who is at high risk of developing severe cognitive impairments in the near future, we can target these individuals and include them in trials of new drug therapies for cognitive issues.”

Most, but not all, patients with Parkinson's disease may experience cognitive impairments, but these can take anywhere between two and 20 years to develop. The silver bullet for patients – and their clinicians – therefore, will be predicting which patients are at the highest risk of developing dementia or similar cognitive problems.

“If we know who is at high risk of developing severe cognitive impairments in the near future, we can target these individuals and include them in trials of new drug therapies for cognitive issues. If you can target them before they develop cognitive impairments you have a better chance of delaying the onset, or even preventing it,'' Melzer says.

“New therapies also have side effects so you don't want to give them to those who are unlikely to develop cognitive problems for quite some time.''

Melzer became involved in Parkinson's research during his PhD studies at the University of Otago, Christchurch, under the supervision of Professor Tim Anderson and NZBRI research director Dr Michael MacAskill. Melzer already had an undergraduate degree in physics, as well as a BSc (Hons) in medical physics.

His study with Anderson, who is NZBRI clinical director, turned up a job opportunity. “I was fascinated by medical imaging,” Melzer says. “I thought it was so cool. The New Zealand Brain Research Institute had just started a Parkinson's disease project and needed someone to investigate the imaging side of the study.''

He credits the foresight of Anderson and Professor John Dalrymple-Alford (a psychologist from the University of Canterbury who is part of the NZBRI) for much of the longitudinal study's current success.

“Tim Anderson and John Dalrymplre-Alford were ahead of the curve. They started compiling a database on cognitive aspects well before others were doing it internationally. Because of this, we now have access to great longitudinal data and will hopefully be able to better understand what specific changes in the brain result in cognitive issues, and be able to better help those people most at risk.''