what being overweight does to your brain
A recent Canadian study discovered pretty concerning links between weight in midlife and risk of Alzheimer’s disease. While it’s been long known that having excess weight in adulthood leads to a range of different health complications, such as high blood pressure, diabetes and high triglycerides, recent researches show that excess weight has also been related to brain shrinkage, called brain atrophy, and cognitive decline.
Adapted from Wisdom Wednesday podcast episode
There are also some reports showing that obesity has been linked to Alzheimer’s disease-related changes, such as damage in the brain called cerebral vascular damage and amyloid beta plaques accumulation, which are the nasty proteins that accumulate in Alzheimer’s disease. However, before this Canadian study, no research has been conducted looking at a direct comparison between brain shrinkage or atrophy patterns in both Alzheimer’s disease and obesity.
So what these Canadian researchers did was compare patterns of brain atrophy and amyloid beta protein accumulation in both obesity and Alzheimer’s disease using a sample of 1300 individuals from 4 different groups. They had a bunch of people who had Alzheimer’s disease, another who had some healthy controls, another who had some obese but otherwise healthy individuals, and another who were lean individuals, and had them all age matched.
For a little bit of a background, obesity has been increasingly recognised as a multisystem disease. It is known to affect your respiratory, gastrointestinal and cardiovascular systems amongst others and also linked to type 2 diabetes, hypertension, and all of that. But only recently, it’s been shown that besides these metabolic changes, obesity is also related to changes in the central nervous system and linked to poor cognition.
There was a recent study using the 20,000 UK Biobank data that showed increased body mass index, body fat percentage and waist-hip ratio were related to worst fluid intelligence and working memory. These are things that are also affected in both pre-clinical and clinical Alzheimer’s disease.
The Canadian researchers theorized that neurodegeneration, which could be measured by the thinning of the cortex called cortical thinning, is the main mechanistic pathway that drives the cognitive changes. And this is a really important hypothesis because the study looked at the mechanisms behind some of the changes that we see in Alzheimer’s disease.
When the research team studied the brains of their participants, they found that the Alzheimer’s group and the obese group showed similar gray matter atrophy in two areas of the brain: the right temporal-parietal cortex, the area involved with attention; and the left prefrontal cortex, the area that’s involved in problem-solving, understanding, reason and a few other things. And they also found that the patterns of obesity-related gray matter atrophy of the brain, didn’t overlap with the amyloid beta or the tau protein distribution in the brains of people with Alzheimer’s disease.
So, this means is that Alzheimer’s disease can be driven by obesity—that’s the driver, the actual founding cause of obesity is the thinning of these areas that predisposes them to the amyloid beta and the tau protein distribution. One thing noted about looking into the brains of these people with obesity is that they’re showing early signs of mechanism for Alzheimer’s disease. This means that a big take away from this study clearly has to be about watching your weight in midlife.
Although they used obesity in the study, it doesn’t mean that once you hit a BMI of 30 or more that you instantly have all of these risk factors; this is just what they used as an arbitrary cutoff for obesity. If you don’t understand BMI, you can use a BMI calculator, input your weight in kilos and divide that by your height in meters squared. Now, if your BMI is 29/28, this won’t mean that you’re absolutely fine and it’s just a tip over 30 that all of these risks happen. What this is showing is that the accumulation of excess body fat has a multisystem negative effect throughout the body and the brain, and maybe mechanistically linked to the development of Alzheimer’s disease.
If you're still reading, you maybe going into a panic if you or someone you know are struggling with weight. Paul will be doing a podcast and blog on approaches to weight loss very soon, so stand by!
Corporate burnout to mental fitness
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