Type 2 Diabetes, Brain Health and Causality: A Complex Relationship

What is it about?

The article discusses the strong association between type 2 diabetes and a twofold increase in the risk of dementia. The pathways that could mediate this association include hyperglycemia, insulin resistance, inflammation, and vascular endothelial dysfunction. The study by Garfield et al. attempts to clarify causality in the relationship between type 2 diabetes and dementia using Mendelian randomization in the UK Biobank. The results showed no evidence to support causality of the relationships of diabetes and glycemia with the outcome measures used. The study has limitations, including a low prevalence of diabetes in the sample and the use of relatively insensitive measures of dementia. Future studies with more sensitive imaging markers and dynamic manipulation of exposure states may provide a better understanding of the brain's response to diabetes-related insults and ways to protect it.

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Why is it important?

The research is important because it aims to clarify the causality between type 2 diabetes and dementia. Understanding the causal relationship between these two conditions could help identify targeted interventions to reduce the risk of future dementia. Key Takeaways: 1. The study used Mendelian randomization to tackle confounding and reverse causation in the relationship between type 2 diabetes and dementia. 2. The study found no evidence to support causality of the relationships of diabetes and glycemia with the outcome measures used, including cognitive function, brain MRI, and Alzheimer dementia diagnosis. 3. The study acknowledges certain limitations, such as the low prevalence of diabetes in the sample and the small range of cognitive tests used. 4. The use of more sensitive imaging markers for dementia, such as diffusion MRI and functional MRI, may be more valuable at earlier ages. 5. The relationship between type 2 diabetes and neurodegeneration may be less likely related to amyloid-related pathways and more related to tau-related pathways.