AF Association

Long-term overtreatment with warfarin raised risk for dementia

Anti-coagulate or not becomes a choice of risk it seems. I am at a loss to know how a doctor can advise definitively on what is the best or least risky choice especially if a patient is taking multiple drugs and/or supplements. It seems doctor's recommendations are based on their knowledge of the studies they happened to have read to date, what drug companies say, and their knowledge of the patient's present health situation. Their decisions are influenced by what they can remember; and, in some countries, by their liability insurance coverage. Anybody play roulette? It seems doctors do and patient's lives are their chips.

I just read an article on thalidomide babies in the Saturday Toronto Globe and Mail paper so maybe I feel a bit jaded. The US did not approve this medication thanks to the efforts of a Canadian who stood up to the FDA. Yet, Canada, which allowed the drug to be sold the longest, has done the least to help these people. One mother said she took only one pill and her baby was born deformed. Unfortunately, this is not the only case where drugs have been found to cause disastrous consequences.

The website below is a summary of yet another study.

10 Replies

Hi Eng Mac

Well yes I suppose it is another thing to worry about, if you let it in my opinion.

From the article two things, most importantly it only applied to those whoe were OVER anti-coagulated, which from what a lot of people say here, and my experiences especially of the NHS is only a few, they seem to panic like heck when you get to 3, which the article says is over anti-coagulated. It also said LONG TERM over anti-coagulated, and whilst some might bounce to 3 or 3.5 doesn't seem like many people stay there for long.

Secondly of course, it was a relatively small sample, didn't seem to look at other factors for dementia (and increasingly we know there are many of these in our modern world) so for me, the very present risk of 5 times stroke would outweigh any fears I may have about possibly suffering from dementia later.

Having said that dementia is an awful condition, and I can understand anyone's fears here, but for me not enough to worry about warfarin.

Be well



Unless I read it wrong it also talks about over anticoagulation ALONG WITH ANTIPLATELET medication. Since few people in UK at any rate are on both warfarin and aspirin for AF then I think we can discount this for most people in our group and a Ian says, we are more likely to be under our target INR.

In my view this is just scaremongering and unhelpful to most people. There is just as much risk of dementia arising from multiple micro strokes as a result of lack of proper anticoagulation so lets move on eh? Life is risky and you'll never get out alive.



I'd have thought long-term over-treatment with anything is going to have bad results. Clue's in the title really!



It's interesting you mention food supplements as well as other drugs?

I will have a luck at the article later today. I constantly worry about all meds I take and there side effects either individually and combined. Although I always felt (maybe wrongly) that food supplements did not hold all the nasties of manufactured drugs.

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I am taking some comfort in the 'over treatment' thing... It's another worry of course. My father was on warfarin and ended up with dementia, but he also had Parkinson's, which is known to be a cause - in this study, would they just have looked at the warfarin and made a link, I wonder?



If you turn the argument around, it's actually good news. We always knew there's a higher risk of dementia with AF. The survey shows that those who have an INR > 3 more than 25% of the time have a 2.4 times higher risk of dementia. So as long as you keep your INR in the 2-3 range most of the time, you have just 40% of the chance of getting dementia! That's easier to achieve nowadays with Coaguchek monitors and our knowledge of Vit K interaction.



Thank you- a useful article and helpful in our attempts to get more frequent INR testing ( to prevent out of range INR in either direction) or more test strips for self-testers. Very useful


I saw a very good article stating the best action for high INR and it was only when it went to 8 it was looked at as a major problem. I do think the risk of stroke out ways dementia risks. We are living a lot longer now so some of these evil problems we die out of are rearing their ugly heads more!

However I do think that things should ever get complacent on any drug. I also have PH and most of that is treated with drugs for other problems as the numbers for people with PH are low and reduce big spends on research? It is the actions and side effects that make them viable?

Be Well


Keeping INR levels between 2-3 is the key and it's pretty clear to me in the article.

Being correctly anti-coagulated we have approx a 66% better chance of not having an AF related stroke. Over anti-coagulation increases the risk of dementia by 25%, but again keeping within the recommended range cuts this risk.


Eng mac,

The doctors and roulette... Of the basis to their advice you forgot to mention medical studies of 7 to 13 (specialists) years and clinical experience. In my opinion drs are experts in their field of education and expertise like any other. Electrician or plumber or university professor. You go and ask for advice and opinion. Maybe you can even trust that dr is doing the best he/she can. If not, you must seek another opinion. It can be a bit dangerous to think that reading a couple of articles in internet could give one a good picture of what is going on. It is a good thing for us patients as a basis to be able to discuss with drs and understand better their advice and help us to make decisions. But it is not expertise.

As Bob and Ian already mentioned, the patients in that article were treated witn an antiplatelet drug as well. And that for a reason, I suppose. They had more valvular disease, renal problems and PRIOR bleedings. As basis for dementia was mentioned cerebral microbleeds. As we know AF patients have silent microclots in their brain. So, what do you choose ?? The follow-up time was 10 years.

There was also a kind of alternative possibility of using new anticoagulants. Is it proven they are more safe in long term.

There was also a publication about more selective NSAIDS in internet. People using them have more cerebral clots already in 30 days of use compared to the older less selective NSAIDS. Heart problems have been reported earlier. And this after several years of clinical use.

So, I tend to think like Bob, that warfarin is an old trusted friend for AF patients. For those of us with any difficulties using it, thera are a few new anticoagulants to choose.


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