Brain Health and Insulin Resistance

A recently published paper [1] further confirms the growing focus on viewing cognitive function through the lens of metabolic health. We’ve known this for years, with regards to Alzheimer’s disease in particular, that the more the person suffers from metabolic disorders, such as insulin resistance, the more compromised the cognition becomes, with a much greater risk in developing Alzheimer’s disease. Unfortunately, this doesn’t appear to be something that is strictly found in older adults.

The scientists performed a variety of metabolic assessments, including body fat and insulin resistance, in teenage boys and girls, and correlated those markers with changes in brain structure and cognitive tests. Interestingly, there was no relation in the young men–metabolic markers had no apparent effect on brain and cognitive outcomes. However, the young women were not so fortunate. In the young women, the higher the insulin resistance, the smaller certain areas of the brain were. Of course, these are microscopic changes, but the volume of various structures within the brain was smaller. Beyond the physical changes in the brain, as modest as they might have been, although statistically significant, they also detected changes in cognition as measured with a handful of mental tests. One of the tests the scientists used is one you might be familiar with, called the Stroop test. This is the kind of test where you have a series of words in different colors. For example, you’ll see the word “green” spelled out, but it’s actually in a blue font. Or you’ll see the word “red,” but it’s in a yellow font. And you have to say the color of it rather than read the word. In the young women, but not the young men, the higher the insulin resistance, the worse the cognition.

As an important reminder, this study only established a correlation–it was not a clinical study. Hopefully, this kind of study might be followed up by looking at the degree of improvement in cognition following an improvement in insulin resistance. In other words, perhaps future work will take the young people when they’re insulin-resistant, improve their insulin sensitivity, and then perform the same tests. That has not been done. Despite the experimental limitations, the results of this study are shocking and noteworthy. Metabolic health, even in the young, can impact brain health.

References

1. https://pubmed.ncbi.nlm.nih.gov/34875560/