One of my blogs last week focused on the potential impact statins have on the development or symptoms of dementia. Interest in this area is an example of the growing recognition that statins have the ability to affect brain functioning. As I briefly mentioned last week, even the Food and Drugs Administration in the US has recognised the potential for statins to induce symptoms such as memory loss, forgetfulness, and confusion.
There is no doubt that statins have the potential for toxicity. However, any direct affects on the brain has generally been believed to be related to the ability of statins to cross what is known as the ‘blood-brain-barrier’. An agent’s ability to breach the blood brain barrier is traditionally thought to be related to several factors, including its affinity to fat or water. Substances that have a high affinity for fat are described as ‘lipophilic’ and have traditionally been believe to cross the blood brain barrier relatively easily. On other hands, conventional wisdom tells us that substances with a high affinity for water (‘hydrophilic’ compounds) do not cross the blood brain barrier readily.
It is known that some statin drugs such as atorvastatin (Lipitor) are lipophilic, white others such as pravastatin (Pravachol) are hydrophilic. In theory, atorvastatin would be expected to be more likely to have adverse effects on the brain compared to pravastatin.
This week saw the publication of a study in which rats were treated for 18 days with one of two statins: pravastatin (Pravachol) or atorvastatin (Lipotor) [1]. Before during and after treatment, the rats were subjected to a learning test. This was adversely affected by pravastatin but not atorvastatin. The animals were also subjected to a memory task, which was also adversely affected by pravastatin but not atorvastatin. The adverse effects induced by pravastatin were ‘reversible’ (resolved on discontinuation of the drug).
These results are the perhaps the opposite of what one might expect from the theory of the propensity of different statins to gain access to the brain. However, the authors of the study point out that pravastatin tends to distribute itself more widely in the body than atorvastatin, and this may ultimately increase pravastatin’s ability to gain entry to the brain.
As to how statins may impair brain function, the researchers suggest one potential mechanism directly relates to lowered cholesterol levels. Cholesterol is required, among other things, for the formation of the fatty sheathes (myelin sheathes) that surround nerves, and any disruption in this may impair neurological functioning. Cholesterol also contributes to the functioning of ‘synapses’ – the tiny gaps between cells via which nerves communicate with each other.
I suspect we have much to learn about the potential for statins to disrupt brain function, and this recent animal study is only a small piece in the puzzle. However, it does support the idea that different statins can pose different risks here, and suggests that the conventional wisdom on lipophilic statins being more hazardous than hydrophilic ones may not actually hold true.
References:
1. Stuart SA, et al. Chronic Pravastatin but Not Atorvastatin Treatment Impairs Cognitive Function in Two Rodent Models of Learning and Memory. PLoS ONE 8(9): e75467
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Dr B,
Did you post on the Sultan & Hynes study – http://file.scirp.org/Html/3-1980073_34065.htm
“The Ugly Side of Statins. Recent Appraisal” – accepted June 12, 2013.
Sláinte
LeonRover,
Thank you for the link to the Sultan Hynes paper. Anyone currently taking statins or considering taking them should read it.
Thank you so much, LeonRover, for that link. What an eye-opener. I stopped taking statins 10 months ago and feel so much better. Even my somewhat thinned hair has all grown back and the other side effects have all gone. At my first diabetic check after I stopped my cholesterol level had risen a little (though I wasn’t given a breakdown of LDL, HDL or triglycerides, but my HBA1c had reduced to almost normal levels (I’ve been a MODY for 56 years.)
Despite this, a doctor at my surgery pressured me to restart the statin “because of the diabetes.” Strange to tell, I resisted and persist with an old fashioned low carb regime.
By the way, for anyone interested, since going low carb (c40 grs) all the fire has gone out of my psoriasis. It’s still there but no longer hot and itchy. That seems to me to confirm the inflammatory properties of carbohydrate.
Dear Dr Briffa,
I have been following your newsletter for a long time and recently was influenced by your adverse comments on statins. My Doctor prescribed simvastain and I decided to stop taking them. I was pleasantly surprised to find that my memory recall has improved considerably since stopping which confirms your latest blog. I am relieved by this as I had no idea that the loss of memory was drug induced. I am 80 yrs young.
I wonder how many people in nursing homes are needlessly coninuing taking statins, if their diet has changed radically in the time they have been there. Just last week I managed to have my mother’s cholesterol re-checked by her doctor, which would not have happened if I had not insisted. I had hoped they could reduce the dosage at least, and was delighted to find she is off them completely since Monday!
She had always looked after her diet, cooking all her meals from fresh, but unfortunately had a sweet tooth so cakes and biscuits were plentiful every day. The sugar and high saturated fats will have contributed to her cholesterol problem. The home she is in cook very good food and her cake intake is minimal, so it made sense to explore this. Already I have noticed the difference in her, as yesterday we played cards and she was, concentrating very well. Of course she suffers all the symptoms associated with Statins including muscle-wastage, memory-loss, cataracts, etc. I believe that most of the drugs churned out in nursing homes are unnecessary, and contributing to dementia and alzheimer’s – these people should have their drug dosage intake regularly monitored, as no doubt their diets were much different before they moved to a nursing home.