Doctor concludes LDL cholesterol may be required to maintain or support memory function

This study was published in the Journal of Alzheimers Disease 2013;34(1):273-9

Study title and authors:
Very old adults with better memory function have higher low-density lipoprotein cholesterol levels and lower triglyceride to high-density lipoprotein cholesterol ratios: KOCOA Project.

Katsumata Y, Todoriki H, Higashiuesato Y, Yasura S, Ohya Y, Willcox DC, Dodge HH.
Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA. katsumat@ohsu.edu

This paper can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/23207484

This study investigated the association between cholesterol levels and memory function. The study included 193 participants, aged 80 and older.

Regarding LDL cholesterol levels, the study found those with better memory function had significantly higher LDL cholesterol levels.

Dr Katsumata concluded: "LDL cholesterol, especially large, buoyant LDL may be required to maintain or support memory function among older people."

Links to other studies:
High cholesterol levels boost memory function
Low cholesterol levels associated with slow mental processing in students
High cholesterol levels are associated with higher intelligence

Low cholesterol levels are associated with poor memory

This study was published in Arteriosclerosis, Thrombosis, and Vascular Biology 2008 Aug;28(8):1556-62

Study title and authors:

Low HDL cholesterol is a risk factor for deficit and decline in memory in midlife: the Whitehall II study.

Singh-Manoux A, Gimeno D, Kivimaki M, Brunner E, Marmot MG.

INSERM U687-IFR69, Hôpital Paul Brousse, Bât 15/16, 16 Avenue Paul Vaillant Couturier, 94807 Villejuif Cedex, France. Archana.Singh-Manoux@inserm.fr

This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/18591462

The study investigated the association of cholesterol levels with memory. 3,673 male and female participants, average age 61, were subjected to a short-term verbal memory test.

The study found:
(a) Poor memory was found in 53% more subjects with the lowest levels of high density lipoprotein (HDL) cholesterol, below 40 mg/dL (1.0 mmol/L), compared to those with the highest levels of high density lipoprotein (HDL) cholesterol, above 60 mg/dL (1.5 mmol/L).
(b) Poor memory was found in 10% more subjects with the lowest levels of cholesterol, below 200 mg/dL (5.1 mmol/L), compared to those with the highest levels of cholesterol 240 mg/dL (6.2 mmol/L).

The results of the study indicate that low cholesterol levels are associated with poor memory.

Links to other studies:
High cholesterol levels boost memory function
High cholesterol levels are associated with higher intelligence

High cholesterol levels boost memory function

This post contains a synopsis of a study published in the American Journal of Geriatric Psychiatry 2008 September; 16(9): 781–785

Study title and authors:
Better memory functioning associated with higher total and LDL cholesterol levels in very elderly subjects without the APOE4 allele
Rebecca West, M.A.,1 Michal Schnaider Beeri, Ph.D.,1 James Schmeidler, Ph.D.,1 Christine M. Hannigan, B.S.,1 Gary Angelo, M.S.,1 Hillel T. Grossman, M.D.,1,2 Clive Rosendorff, M.D., Ph.D.,1,2 and Jeremy M. Silverman, Ph.D.1,2
1Mount Sinai School of Medicine
2James J. Peters Veterans Affairs Medical Center

This study can be accessed at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2614555/

Apolipoprotein E (APOE) is found in some types of lipoptoteins that carry cholesterol around the body. About 20-25% of the population have the genetic type APOE4 allele.

 
The study examined the association of cholesterol with cognitive functioning in 185 people aged over 85 with and without the APOE4 allele.
 
The study found:
(a)  high total cholesterol and high LDL cholesterol were associated with higher memory scores for non-carriers of the APOE4 allele.
(b) there was no significant associations between cognitive performance and cholesterol levels were found for carriers of the APOE4 allele.
 
In conclusion the study found high cholesterol levels boost memory function for about 80% of the population and has no effect on the other 20%.

Learning, Your Memory, and Cholesterol

This post features an article by Chris Masterjohn and a recipe for buffalo-zucchini fritatta.

Learning, Your Memory, and Cholesterol
July, 2005 by Chris Masterjohn

One of the many important roles cholesterol plays in the body is in our nervous system, enabling learning and memory to take place. In fact, one of the reasons that sleep is beneficial to our learning and memory is because it enables our brain to make more cholesterol!

Books:

While the war on cholesterol is waged full-speed ahead, and many web sites are now touting low-fat, low-cholesterol diets as "brain-healthy" due to unfortunate misinterpretations about the role of a cholesterol byproduct in Alzheimer's disease, science is continually showing that cholesterol is one of the most important parts of our brains.

Sleep, Memory, Learning, and Cholesterol

Evidence to date strongly supports the concept that sleep plays an important role in increasing performance of newly learned activities, consolidating memories, and increasing brain plasticity-- which is the ability to form new, as well as break, connections between neurons called synapses.

These benefits of sleep are not simply the absence of stress from sleep-deprivation, but an independent, critical role, in the actual process of learning and memory-formation.1

But why?

Exciting research was published in the pages of Neuron last year (2004),2 identified about 100 genes that increase their activity during sleep. They found about as many that increased their activity during wake, and others whose activity varied with circadian rhythm, independent of sleep or wakefulness.

While there are many important cellular and molecular events that happen during sleep, and we are only cracking the surface in our understanding of them, one of the things this study showed is that cholesterol synthesis increases during sleep-- which, given the research described below, undoubtedly is part of the reason sleep is beneficial to mental functioning.

Cholesterol is abundant in the tissue of the brain and nervous system. Myelin, which covers nerve axons to help conduct the electrical impulses that make movement, sensation, thinking, learning, and remembering possible, is over one fifth cholesterol by weight.3

Even though the brain only makes up 2% of the body's weight, it contains 25% of its cholesterol.4

One of the groups of genes that the above study found to be upregulated during sleep were genes important for the synthesis and maintenance of myelin, including myelin structural proteins and genes relating to the synthesis and transport of cholesterol.

But the benefits of cholesterol extend beyond both sleep and myelin. In fact, in 2001, cholesterol was found to be the most important factor in the formation of synapses, the basis of our learning and memory.

Memories and Learning are Directly Dependent on Cholesterol

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.

Neurites Lose Their Way Without Cholesterol

"Neurites" refer to the extensions from the cell of a neuron that connect with other neurons or muscles. The type of neurite that sends impulses away from the cell is an axon, and the type of neurite that receives impulses is a dendrite.

Connections between neurons, called synapses, are contantly being formed and broken in our brains, where dendrites and axons meet.

But they can't just grow randomly. Neurites grow in response to a stimulus given by a signaling protein in the membranes of neurons.

These signaling proteins rely on lipid rafts, which are beds of cholesterol and phospholipids made from long-chain saturated fatty acids that secure some proteins.

A 2004 study found that disrupting lipid rafts by extracting some of the cholesterol from the membrane of a neuron completely destroyed the ability of neurons to find the signaling proteins attracting them!6

Statins Could Kill Your Memory — Eggs Could Cure It

We now know that the formation of synapses, or connections between neurons, is directly dependent on the availability of cholesterol.

The formation of these synapses are what give us the ability to remember and learn. The benefits of sleep for memory formation and learning are in part a result of increased cholesterol synthesis during sleep.

The implications are important and powerful. In our society's quest to lower cholesterol at all costs and without second thought, could some of the methods we use, such as taking cholesterol-lowering drugs, or eating low-fat, low-cholesterol diets, be limiting the availability of cholesterol to our nervous system?

The authors of the 2001 Science study described above concluded that the "results imply that genetic or age-related defects in the synthesis, transport, or uptake of cholesterol in the CNS may directly impair the development and plasticity of the synaptic circuitry."

But the authors left out one thing: in addition to genetic or age-related defects, there is currently a booming industry founded upon the deliberate inhibition of the synthesis of cholesterol using pharmaceutical drugs. Some statins cross the blood-brain barrier (BBB); others may affect cholesterol levels in the brain without necessarily crossing the BBB; still, without crossing the BBB, the peripheral nervous system could likewise be damaged.

In fact, amnesia and cognitive dysfunction are reported as side-effects in some statin users. Dr. Duane Graveline, MD, former NASA scientist and astronaut, describes his bout of statin-induced memory loss, in which his wife caught him wandering aimlessly in his yard while he failed to recognize her.

In an article on the side-effects of cholesterol-lowering drugs, the Geriatric Times cites two randomized trials, several case reports, and one large case series pointing to memory loss as a result of statin drugs.

Conversely, dietary cholesterol can help reverse the effects of declining memory with age.

Mary Enig, PhD, cites a study in her book, Know Your Fats, that found that the cholesterol in eggs can help improve memory in the elderly.5

Remember...

One of the basic parts of ourselves that defines us as humans is our mind. We imagine, think, study, learn, remember, come up with new ideas, remember old faces, and form friendships and familial relationships that are based, in large part, on our memories of those people.

Cholesterol is a central building block of the connections within our brain that hold these memories and learning processes together. Remember that... thanks to cholesterol, you can!

This article can be accessed at: http://www.cholesterol-and-health.com/Memory-And-Cholesterol.html

More information on this subject: Books : Scientific Studies : Other Websites : Videos : Food Mall 

Recipe of the day

Buffalo-Zucchini Fritatta

Makes 2 Servings

Ingredients:

Food Mall: Ground Buffalo

5 Eggs

4oz Ground Buffalo
1 Large Zucchini, grated

Instructions:
Preheat oven to 350F.

In a bowl, whisk the eggs with a splash of water. Set aside.

In an omelet or saute pan over medium-high heat, cook the buffalo until browned and cooked through. Add the zucchini and stir.

Add the egg mixture.

Place pan in preheated oven and continue to cook until set, about 5-10 minutes (depending on pan).

Gently shake the pan to loosen the frittata and slide it onto a serving plate.