Diabetes, ageing, and the brain

This page gives an overview of what I'm joyfully frolicking with working on in my postdoctoral position at the Centre for Research on Ageing, Health and Wellbeing at the Australian National University.

My position is supported by the NHMRC grant 1063907, "Too sweet for our own good: An investigation of the effects of higher plasma glucose in the normal range on cerebral health", led by Associate Professor Nicolas Cherbuin and Professor Kaarin Anstey.

This is my personal records/musings, so none of the below should be taken as officially endorsed by Nic, Kaarin the ANU, or NHMRC (or anyone else, for that matter).

Especially as I'm having altogether too much fun working on this stuff and I'm told research glee isn't a good fit for official things.

 

The impact of blood glucose on the brain

  • We know type 2 diabetes impacts negatively on the brain, for example diabetics have slightly smaller brains and faster age-associated brain shrinkage than non-diabetics
  • There is growing evidence that high blood glucose levels in the non-diabetic levels might also be associated with adverse health outcomes

This project is about exploring the impact of high blood sugar on the brain.

Here is a short video introduction I made about this research.

Click to read the presentation slides: Walsh, E., Shaw. M, Anstey, K., and Cherbuin, N. (2015) Glucose on the ageing mind. Healthy brain ageing: Developing a better understanding to support prevention (Canberra, 24th September)


High 'normal' blood glucose is associated with total brain atrophy in the 60s

Working with M.E. Shaw, P. Sachdev, K. Anstey and N. Cherbuin

Past research has demonstrated that type 2 diabetes is associated with brain shrinkage,and accelerated brain atrophy. There's some evidence that high blood glucose in the normal range might also impact on the brain, so we looked into whether this is true in ageing brains, and in men and women.

Click to read the poster: Walsh, E., Shaw, M., Sachdev, P., Anstey, K., & Cherbuin, N. (2016) Sex effect in the association between fasting blood glucose and total grey matter volume in the 60s. Organisation for Human Brain Mapping (Geneva, Switzerland, 26th-30th June)

This research was discussed on ABC 666 radio (Sunday Brunch with Lish Fejer, 8/5/2016).

The impact of diet on the ageing mind and body

  • We know diet can impact on the brain and the body
  • There's a heap of different ways to measure diet and it's impact on the brain and body
  • New techniques and perspectives can help us really work out what's going on
This project is about filling in the gaps in our knowledge about the interplay between diet, demographics, and health outcomes that may impact on the brain.

The association between Western and Prudent dietary patterns and fasting blood glucose levels in type 2 diabetes and normal glucose metabolism. 

Working with F. N. Jacka, P. Butterworth, K. J. Anstey, and N. Cherbuin

This forms the first in a trilogy of papers on this topic. Rather than just looking at one part of the diet in isolation (e.g. just fats, or just proteins), this study looks at the diet as a whole. This gives us new insight into how the diet may affect blood glucose levels, both in and out of the diabetic range.

Western diet and high protein intake are associated with higher body mass index: a longitudinal investigation

Working with D. Hosking, F. N. Jacka, P. Butterworth, K. J. Anstey, and N. Cherbuin

Just like a good movie trilogy, the last paper got the character development out of the way, and now it's time to focus on the meat of the story. This is similar to the diet-glucose project, except this time we're focusing on how diet can impact body weight.

This work was presented as a talk at the Emerging Researchers in Ageing conference (Canberra, October 31st 2016), Deconstructing diet: investigating the link between diet and body weight in ageing. Click here to read the slides.

Adiposity and blood glucose: a problematic relationship well before diabetes sets in

Working with K. J. Anstey, R. Burns, and N. Cherbuin

This forms the final piece of the diet-body weight-glucose trilogy. Short and sweet, this seems like such a straightforward topic. Perhaps because it is so straightforward, very few people have actually looked at it as parsimoniously as we do here.

Physical Activity is not associated with plasma blood glucose levels in the PATH study

Working with K. J. Anstey, and N. Cherbuin

This paper is currently on hold.

The shape of the corpus callosum

  • The corpus callosum is the main pathway for neurons connecting the left and right brain hemispheres.
  • Shape analysis provides unique insight into biological processes, but it can be tricky to work out what kind of analysis is best, and how it should be used.
  • Analyzing the shape of the corpus callosum may prove highly informative for addressing a number of ongoing questions in the neuroscience literature

This project is about exploring demographic characteristics that are associated with the shape of the corpus callosum.

 

Here is a video of me talking about this research, for the 2015 FameLab national finals.

Video courtesy of Mixed Media, © British Council 2016. Visit www.famelab.org.au for more exciting insights into the science early career researchers are getting on with!

Analysis of corpus callosum shape using polygonisation and Fourier techniques

Working with M.E. Shaw, D. A. Espinoza Oyarce, M. Fraser, and N. Cherbuin

Before we can start to talk about how the shape of the corpus callosum is related to demographic characteristics, we need to work out how to analyse shape. There are heaps of shape analysis techniques out there, but not much to help us pick the best technique for our work. This is a methods study, so it focuses on how to use techniques, and how well they work. We chose two promising techniques (polygonisaton and fourier analysis), and tried them out. We saw how analyses performed when we knew the right answer (by using simulated shapes), and when we didn't (by using real corpus callosum shapes). After considerable statistical gymnastics, we picked the best shape analysis technique to use in the rest of our work on this project.

Click to read the presentation slides: Walsh, E., Shaw, M., Fraser, M.,Anstey, K., & Cherbuin, N. (2016) Geometric morphometric analysis for quantifying and categorising brain structure shape in diabetic and non-diabetic populations. Australian Mathematical Psychology Conference (Hobart, Tasmania, 10th-12th February)

This research was discussed on ABC 744 radio (Evenings with Lindy Burns, 27/4/2016).

Global corpus callosum shape: a longitudinal investigation of sex differences

Working with M.E. Shaw, P. Sachdev, K. Anstey and N. Cherbuin

We know that there are differences between male and female brains. For example, men tend to be better at mental rotation tasks than women. There's good evidence that this is because when doing things like reading maps or imagining three dimensional shapes, men use the right side of their brain more than women, who use a mixture of the left and right sides of the brain. It's also possible that men are using different parts of their brain to do the same task. When we're talking differences in the symmetry and distribution of how the brain is wired between the hemispheres, we're talking possible differences in the shape of the corpus callosum. But, although we'd expect there to be sex differences in corpus callosum shape, there's a mixture of papers saying "yes, there's a difference", and papers saying "no, there isn't!". Thanks to our methods paper, we've got a shiny novel technique for exploring corpus callosum shape. We've also got a great dataset of men and women of different ages, where we can also look at change in corpus callosum shape over time. This study investigated sex differences in corpus callosum shape in a large sample of community-living middle-aged adults. 

The impact of blood sugar on global corpus callosum shape: a longitudinal investigation

Working with M.E. Shaw, P. Sachdev, K. Anstey and N. Cherbuin

We know that diabetes and high blood sugar can shrink some parts of the brain. Does diabetes change the shape of the human corpus callosum? What about high blood sugar in the normal range? And if it does impact on shape, what does this mean in terms of how our brains work? These are the questions we're tackling in this study.

The impact of blood sugar on on corpus callosum shape change in middle age

Working with M.E. Shaw, P. Sachdev, K. Anstey and N. Cherbuin

The corpus callosum is a bit like the human ear - there's a basic consistency in overall shape, but there are MANY differences between individuals. This provides a very particular challenge to researchers trying to analyse corpus callosum shape change over time. It's important to sort out the differences between people from the differences within people. This study pays special attention to sorting out within- and between- person differences to see if the corpus callosum does change shape over time.

Bonus Dr. Walsh fact: corpus callosum contours are up to 90% more adorable with the addition of a smiley face:

cc_smiley.jpg