In the late 1990s and early 2000s, research was pointing to an unknown compound made by glial cells that was responsible for the ability of neurons to form synapses, or connections between each other.
Thoughts, memories, learning, and all mental function is dependent on the formation of synapses, so the ability to form them will directly impact mental functioning and health.
In the absence of this-- as yet unknown-- "glial factor," neurons formed few synapses, and the synapses they formed were inefficient and poorly functioning. In the presence of glial cells, which secrete the unknown factor, neurons formed many, highly efficient synapses.
So what is this "glial factor"?
Research in 2001, by Mauch, et al., published in volume 294 of Science magazine, determined that the unknown glial factor is cholesterol, which is released by the glial cells in a carrier called "apolipoprotein E."5
Initially, the researchers thought that the apolipoprotein E (apoE) may have been the glial factor itself. But it turned out that when neurons were treated with apoE, the beneficial effects on synapse formation were not observed.
The researchers then reasoned that, since apoE fit the bill in some ways, but did not have the desired effect, some of the lipids it carried may have been the elusive glial factor.
As it turned out, treating the neurons with a 10 mcg/mL solution of cholesterol increased synapse formation by 12 times! Other lipids, carried by apoE, such as phosphatidylcholine and sphingomyelin, did not have a significant effect, and were even toxic to the neurons at very high doses.
On the other hand, when low-cholesterol glial secretions were produced by using the cholesterol-lowering drug, mevastatin, the effect of the glial secretion on synapse formation was strongly diminished. When cholesterol was added back to the low-cholesterol secretion, the positive effect on synapse formation was fully restored.
The authors identified cholesterol as a limiting factor of synpase formation. In other words, the need for cholesterol in the brain is large enough relative to the supply of cholesterol that the availability of cholesterol can directly limit the ability to form synapses.
The above is from http://www.cholesterol-and-health.com/Memory-And-Cholesterol.html
Statins cause cognitive impairment http://www.peoplespharmacy.com/2012/03/01/new-warnings-on-statins/ .
Vegans have lower IQs than SAD dieters http://www.standard.co.uk/news/vegetarians-are-more-intelligent-says-study-7082629.html .
Treating neurons with a solution of cholesterol increased synapse formation 12-fold. Cholesterol is a/the? Limiting factor for synapse formation which is responsible for all mental function.
asked byStephen_4 (10989)
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on January 11, 2013
at 10:18 PM
A common view among scientists seems to be that most people have a functioning mevalonate pathway and eating cholesterol has little effect on the blood levels of or the cellular utilization of cholesterol.
I looked for studies on cholesterol feeding and intelligence and found a few interesting ones by Bernard Schreurs on rabbits. His description of some of these:
"...we were surprised to find that rabbits fed cholesterol for eight weeks showed improved trace classical conditioning and reflex facilitation of the NMR (Schreurs et al., 2003) and that these facilitating effects of cholesterol were a function of the concentration (Schreurs et al., 2007b) and duration of the cholesterol diet (Schreurs et al., 2007a). These facilitating effects were generalized beyond NMR conditioning because an eight-week, 2% cholesterol diet also facilitated rabbit heart rate conditioning ??? an index of conditioned fear (Schreurs et al., 2007c)".
On the other hand, however, there was a randomized controlled trial on 1076 infants from age 7 months to 5 years which gave nutritional counseling to parents so half of the children were raised on lower saturated fat and cholesterol diets.
By the end of the trial there were no significant differences in the pass/fail rates of intelligence tests between both groups. Take that as you will.
I think I'm leaning towards to view that cholesterol is found in a number of healthy foods and plays really important roles in the body, but most people probably won't see mental health benefits solely from eating it.
on January 10, 2013
at 11:07 AM
Clearly, cholesterol is not the villain its made out to be.
"Since the brain, being only 2% of the body's weight, yet containing a full 25% of its cholesterol, relies on cholesterol as so necessary and central to its function, it is not very surprising that cholesterol would be "involved" in any brain disorder."
on January 02, 2013
at 09:07 AM
"A study of thousands of men and women revealed that those who stick to a vegetarian diet have IQs that are around five points higher than those who regularly eat meat."
Anorexics consistently score higher than their non eating disordered counterparts in IQ tests.
MOST anorexics are vegetarians. I'm willing to bet most vegetarians are anorexics too, whether or not they admit that is up to them.
So they're not smarter because they're vegetarians/vegans, they're smarter because they're anorexic. (I'm being facetious, btw, but it is true that most vegetarians I've met have been more intelligent than the average meat-eating person and also have disordered eating habits and are prone to drug abuse.)
The reason vegetarians are "smarter" is because smart people are more likely to eat healthier because they appreciate the merit that living a healthy lifestyle has. Unfortunately, even smart people can be wrong. I think I'm relatively intelligent, but being a vegetarian was a HUUUUGE mistake. I was stupid and naive back then and I did not do proper research. I came to the logical (or so I thought) conclusion that vegetarianism was the best thing for everyone on planet Earth. I was incorrect, but it was my intelligence that drove me to vegetarianism. I knew that eating healthy was obviously healthy.