Science Round Up Seconds: Are Statins Good for Your Brain? Have the Scientists Just Forgotten About the Risks?

Brainy question of the day: Will statins revive or criple your brain?

Those of you who made it in time for yesterday's live-show, will already know that I have "postponed" publishing the (by then) commented list of dietary supplements to improve and maintain insulin sensitivity to Sunday.

It was my original plan to publish this list along with three suggested supplement stacks on Sunday and sticking to it has the advantage of a "true" ending to the "Maintain and Improve Your Insulin Sensitivity" series (read previous posts) - there is already enough chaos among the 1351 published SuppVersity posts ;-).

Furthermore, it will unquestionable be good for your brain, if I do not flood it with an informational overload by trying to cram all the information about the insulin sensitizers, as well ;-)

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Don't forget to download the podcast: If you have not already done so, I suggest you download and listen to the show. With Carl's questions and comments the radio show does also deliver some extra information that is not part of this summary.

I have to admit that I must have over-read the original article a listener who goes by the name "Rad Fox" referenced in an email he send to onair@superhumanradio.com (feel free to bother us with questions for future episodes). In this email "Rad" referenced an article which turned out to be one of these notorious copy + paste pieces of a press release. The latter came from John Hopkins Medicine and discussed the results of an as of now unpublished paper about the incidence of dementia in patients on statin therapy.

This is not the first review that connects statin use to brain health!

Despite their bad reputation within the health and fitness community, the use of statin drugs has in fact been shown in numerous studies to keep your brain on top of the game. Another very recent meta-analysis of data from studies with 2851 cases and 57020 participants, for example, says that statin use is associatied with a statistically significant -48% reduction in dementia risk (Song. 2013). Similarly, Steenland et al. write in a paper that's been published roughly a month ago:

"Research volunteers with normal cognition at baseline evaluated an average 4.1 times over 3.4 years (1,244 statin users, 2,363 nonusers) and with mild cognitive impairment (MCI) at baseline evaluated an average 3.9 times over 2.8 years (763 users, 917 nonusers)." (Steenland. 2013)

Irrespective of the high number of empirical studies that seem to support the efficacy of statins as "anti-dementia" drug, I did not even have to bother with PubMed or any other medical database to find trials that suggest that the use of statin drugs will have the exact opposite effects. I just had to scroll down to the end of the article, where I found a news report on an study that claims that Pravachol, obviously likewise a statin drug, would be "linked to memory impairment" (read the news story).

Beneficial or detrimental? Which results can you trust?

Your body does in fact produce i's own anti-dementia "drug": Melatonin. With the natural decline of the metlatonion production with age, it is thus only logical that you develop dementia, only in your older age - learn how to protect yourself with melatonin

I know it can be enervating at time, but it's one of the central characteristics of science that it's results are usually ambiguous and far from achieving the status of "undebatable truths". If you've been around the SuppVersity for some time now, you should by now have overcome this naive understanding of the nature of science by now, anyways.

"The promising results obtained in vivo and in epidemiological studies are generally not in accordance with those of placebo-controlled randomized clinical trials." (Silva. 2013)

You should also be aware that the best way to reconcile these discrepancies between epidemiological and experimental evidence is to identify the underlying mechanism behind the effects statins exert on the build-up of neuronal plaque. As soon as we know exactly what's happening we may well be able to decide whether the protective effects we see are "real" or just an "epidemiological Fata Morgana".

The most important question we have to answer is: "HOW?"

Unless we have a rationale explanation for the protective effects statins may have on the brain of (elderly!) individuals, we can file the claim "statins protect elderly brains against cognitive decline" in the "still to be investigated" folder and let it rest there until we have a verifiable theory (= sum of hypothesis) to explain how the use of a drug that was originally designed to block the endogenous production of cholesterol could have such an effect on the brain.

Dietary vs. endogenously produced cholesterol: I know that most of you will be aware that statins reduce your bodies own (=endogenous) production of cholesterol. Most of you will probably also know that it is this endogenously produced cholesterol that is - if any form of cholesterol - to be held responsible for coronary heart disease and (purportedly) the formation of plaque in the brain.

If you are not a narrow-minded text-book physician, you will have to acknowledge that eggs promote an anti-artherogenic cholesterol profile and will thus probably have anti-Alzheimer's and anti-dementia effects (learn more)

For the average human being, his dietary cholesterol intake will have no or only minor influence on the serum levels of cholesterol and cholesterol rich foods such as eggs, have actualle been found to exerd positive effects on the cognitive function of elderly individiuals (Aparicio. 2013); and despite the fact that the results did lose their significance, when they were stratified for total energy intake and education level, the Aparicio study should remind us that the role cholesterol rich foods do not necessarily increase your dementia risk, even if cholesterol was mechanistically involved in the etiology of dementia - even if studies in rodents and rabbits who were fed with synthetic high cholesterol diets suggest otherwise (learn more about the problems with synthetic diets).

And what about saturated fat? In a study from Japan (the Hisayama Study; cf. Ozawa. 2013), the consumption of a diet with a normal amount of saturated fat in it and not the allegedly healthier "almost zero SFA" pattern were associated with reductions in all cause (-34%), Alzheimer's (-35%) and vascular dementia (-55%) - a direct negative effect of saturated fats is thus unlikely. A negative impact of certain foods that happen to have a high amount of saturated foods in them, on the other hand, cannot be excluded.

The most straightforward explanation for the beneficial effects scientists observed in numerous epidemiological studies would obviously be a direct one: "Statins take away a substrate that's necessary for the amyloid plaque to form." This hypothesis would also be supported by significant correlations between elevated serum cholesterol levels and plaque build-up in the brain, as they were observed by (among others) by Matzusaki et al. in who used the same cohort Ozawa et al. analyzed in their study on the influence of certain dietary patterns on the risk of developing dementia (see red box above). In the corresponding paper Matzusaki et al. report:

Table 1: Official "normal" levels for total, LDL & HDL cholesterol, as well as triglycerides (based on AHA recommendations)

• 23x higher risk for total cholesterol > 5.8mmol/L
• 13x higher risk for LDL > 4.02 mmol/L
• 70% higher risk for HDL < 1.04 mmol/L (p > .5)
• 3.5x higher risk for triglycerides >1.56mmol/L
  that's compared to Q1 <0.51mmol/L
• 7x higher risk for LDL / HDL > 3.48 mmol/L
• 3.1x higher risk for “non-HDL” > 4.61 mmol/L

What makes Matzusaki et al.'s observation particularly interesting is the fact that they are based on 147 autopsies that were performed between 1998 and 2003. Autopsies? Yes, I know that sounds gross and irrelevant, but it has the advantage of

• being able to measure the amount of plaque directly,
• having physical and quantitative data, and
• not being limited to diagnosed cases of dementia.

In other words: Your data is not going to be skewed by analyzing only those who are already sick enough to be treated, when you are able to look at the brains of a representative sample of the population after they died.

Dead or alive, there is more than one hypothesis

Remember: We are inclined to forget that the only difference between "effects" and "side effects" is our assessment of the latter. The beneficial effects statins have on the expression of AGE receptors, for example would be  "side effects" for a classic statin which is obviously supposed to lower cholesterol and nothing else. In the context of dementia prevention, this side effect it is the intended effect and the cholesterol lowering effects of statins are the "side effects".

In view of the myriad of already discovered and hitherto undiscovered "side effects" of statins it is however just as likely that the reduced dementia risk is a result of  ...

• a reduction in advanced glycation end product receptors in the brain and thus a protection against the negative effects AGEs exert on the brain (Liu. 2012; Deane. 2012).
  On a side note: If you want to counter the production of endogenous AGEs you can do so with taurine (Nandhini. 2004). This would obviously render the use of a statin to reduce the receptor density obsolete.
• a blockade of the “maturation” from plague precursors to amyloid beta plaque (Hosaka. 2013)

... or a combination of all these effects with the direct and indirect role cholesterol plays in the formation of plaque in the brain (Fantini. 2013; Hung. 2013).

Whether we will ever really know that it is that appears to protect statin users from dementia is thus obviously still anybody's guess. What is not "anybody's guess" is whether it makes sense to take a statin solely to protect yourself from developing dementia. That would - in my humble opinion - rather be a sign of existing cognitive decline than a protection against its development ;-)

Bottom line: Despite the fact that I have never been a statin advocate it is difficult to argue with the current epidemiological evidence: People who take statins have a lower incidence of dementi *fullstop* Whether this is even related to cholesterol is however as questionable as Carl's suggestion that it's an overall reduction in inflammation as it has been observed by Reis et al. (2012) in the context of Malaria infections, where statins appear to be able to sooth the "brainflammation" that's behind the beneficial effects of statin drugs.

Those who take statins can benefit from eating pomegranate | learn more

What is more or less undebatable, though, is that "there is insufficient evidence to recommend statins for the treatment of dementia" (McGuinness. 2013). I will leave you with this conclusion from the latest Cochrane review and a discreet reference to the influence of APO-E phenotypes on both baseline cholesterol levels and the development of Alzheimer's disease. Who knows? If we controlled for the APO-E4 allele, we may well find that carriers of the AA (=2x positive) form of the APO-E4 gene, of which a recent study from the University of Toronto suggests that having this homozygous APO-E4 gene poses a 56.0x higher risk (no typo!) of developing dementia (all forms), benefit from taking a statin while others don't? I will obviously keep you posted on all future developments.

References: 

• Aparicio Vizuete A, Robles F, Rodríguez-Rodríguez E, López-Sobaler AM, Ortega RM. Association between food and nutrient intakes and cognitive capacity in a group of institutionalized elderly people. Eur J Nutr. 2010 Aug;49(5):293-300.
• Barberger-Gateau P, Letenneur L, Deschamps V, Pérès K, Dartigues JF, Renaud S. Fish, meat, and risk of dementia: cohort study. BMJ. 2002 Oct 26;325(7370):932-3.
• Deane R, Singh I, Sagare AP, Bell RD, Ross NT, LaRue B, Love R, Perry S, Paquette N, Deane RJ, Thiyagarajan M, Zarcone T, Fritz G, Friedman AE, Miller BL, Zlokovic BV. A multimodal RAGE-specific inhibitor reduces amyloid β-mediated brain disorder in a mouse model of Alzheimer disease. J Clin Invest. 2012 Apr 2;122(4):1377-92. 
• Fantini J, Yahi N, Garmy N. Cholesterol accelerates the binding of Alzheimer's β-amyloid peptide to ganglioside GM1 through a universal hydrogen-bond-dependent sterol tuning of glycolipid conformation. Front Physiol. 2013;4:120. doi: 10.3389/fphys.2013.00120.
• Liu R, Wu CX, Zhou D, Yang F, Tian S, Zhang L, Zhang TT, Du GH. Pinocembrin protects against β-amyloid-induced toxicity in neurons through inhibiting receptor for advanced glycation end products (RAGE)-independent signaling pathways and regulating mitochondrion-mediated apoptosis. BMC Med. 2012 Sep 18;10:105. 
• Hosaka A, Araki W, Oda A, Tomidokoro Y, Tamaoka A. Statins reduce amyloid β-peptide production by modulating amyloid precursor protein maturation and phosphorylation through a cholesterol-independent mechanism in cultured neurons. Neurochem Res. 2013 Mar;38(3):589-600.
• Hung YH, Bush AI, La Fontaine S. Links between copper and cholesterol in Alzheimer's disease. Front Physiol. 2013;4:111. 
• Matsuzaki T, Sasaki K, Hata J, Hirakawa Y, Fujimi K, Ninomiya T, Suzuki SO, Kanba S, Kiyohara Y, Iwaki T. Association of Alzheimer disease pathology with abnormal lipid metabolism: the Hisayama Study. Neurology. 2011 Sep 13;77(11):1068-75.
• Nandhini AT, Thirunavukkarasu V, Anuradha CV. Stimulation of glucose utilization and inhibition of protein glycation and AGE products by taurine. Acta Physiol Scand. 2004 Jul;181(3):297-303. 
• Ozawa M, Ninomiya T, Ohara T, Doi Y, Uchida K, Shirota T, Yonemoto K, Kitazono T, Kiyohara Y. Dietary patterns and risk of dementia in an elderly Japanese population: the Hisayama Study. Am J Clin Nutr. 2013 May;97(5):1076-82.
• Reis PA, Estato V, da Silva TI, d'Avila JC, Siqueira LD, Assis EF, Bozza PT, Bozza FA, Tibiriça EV, Zimmerman GA, Castro-Faria-Neto HC. Statins decrease neuroinflammation and prevent cognitive impairment after cerebral malaria. PLoS Pathog. 2012 Dec;8(12):e1003099.
• Silva T, Teixeira J, Remião F, Borges F. Alzheimer's disease, cholesterol, and statins: the junctions of important metabolic pathways. Angew Chem Int Ed Engl. 2013 Jan 21;52(4):1110-21.
• Song Y, Nie H, Xu Y, Zhang L, Wu Y. Association of statin use with risk of dementia: A meta-analysis of prospective cohort studies. Geriatr Gerontol Int. 2013 Mar 6.
• Steenland K, Zhao L, Goldstein FC, Levey AI. Statins and cognitive decline in older adults with normal cognition or mild cognitive impairment. J Am Geriatr Soc. 2013 Sep;61(9):1449-55.