We know that obesity, defined as having a Body Mass Index or BMI of greater than 30, is bad for health in general but now we understand that it’s deleterious for the brain specifically.

Axon and dendrite showing the synaptic gap.

The study, performed at the Princeton Neuroscience Institute, began by plumping up male rats to make them obese. The researchers found that the obese rats exhibited cognitive impairment and a shortening of the arms – dendrites – that reach out from brain cells to to other similar cells to create mental pathways.  These dendrites ‘connect’ to other cells by means of synapses. These are kind of a ball-and-socket joint where nothing quite touches and where information is passed by a chemical means.  They also noticed an increase in the activity of microglia, the brain’s immune-type cells. Researchers note in their paper that “microglia play an active role in obesity-associated cognitive decline by phagocytosis, or eating, of synapses.” In more understandable words, the brain is turning on itself, much like an autoimmune disease does, eating that which helps the mind to function.

I don’t know exactly how this correlates to humans and I don’t know at what point obesity-induced cognitive impairment becomes a problem.  I measure up to an even 26.0 for my BMI. Though I’m four points off the of the obese tab for my BMI, I doubt that my brain cells know that. I have been recently tested for cognitive ability (because of my recent accident) and learned that I was within the normal range for people my age and with my education. Hopefully I will continue to improve.


Dendrites emerging from a cell body.

This research is interesting in how it dovetails with that of Dr. Amen of PBS fame  and who is the founder of the Amen Clinics and the author of many books.  He argues that a Mediterranean type of diet is good for the body, and that ‘what is good for the body is good for the brain’. He writes often of people who have changed their diet, lost an amount of weight, and perform better on cognitive tests. They are more energetic and lose the feeling of ‘brain fog’. Could their weight loss have something to do with their improved cognition?

For what it’s worth, I intend to improve my diet. Since my accident I have learned just how fragile the brain and body are but how easily they can be made whole again – once. There is ample evidence that the brain will heal itself if given the right tools – nutrients – once. But as it works to create new pathways it uses new neurons leaving fewer for another injury. I don’t intend to pay dice here.

Your BMI, or Body Mass index, is your weight in kilograms divided by your height in meters. No need to worry: there are plenty of on-line calculators that will do it for you. Google has one here.


Microglia play an active role in obesity-associated cognitive decline, Elizabeth Gould, et. al., Journal of Neuroscience, 10 September 2018, 0789-18; DOI: https://doi.org/10.1523/JNEUROSCI.0789-18.2018 <http://www.jneurosci.org/content/early/2018/09/10/JNEUROSCI.0789-18.2018>

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