The Food and Drug Administration (FDA) in the US is responsible for making decisions about which drugs should be licensed. It also keeps a database of information regarding the adverse effects of drugs, and occasionally revises the warnings issued with prescription medication. Earlier this week, the FDA issued new guidelines regarding the management of individuals taking statins.
The FDA, in its new guidelines, draws our attention to the evidence which links statin use with impaired blood sugar control, and the guidelines warn doctors and patients alike about this. Raised blood sugar levels may ultimately lead someone down a path to type 2 diabetes. However, even in the absence of type 2 diabetes, raised blood sugar levels can damage the body and are associated with an enhanced risk of chronic disease and death.
The FDA guidelines also highlight the fact that statins can, in some, induce mental problems such as memory loss and confusion, telling us that: “There have been rare post-marketing reports of cognitive impairment (e.g., memory loss, forgetfulness, amnesia, memory impairment, confusion) associated with statin use. These reported symptoms are generally not serious and reversible upon statin discontinuation, with variable times to symptom onset (1 day to years) and symptom resolution (median of 3 weeks).”
The potentially brain-sapping properties of statins may possibly be directly related to their ability to deplete cholesterol. Cholesterol is very concentrated in the brain, where it contribute to the functioning of ‘synapses’ – tiny gaps between cells which allows nerves to communicate with each other.
It has been noted that those who take statins (which reduce cholesterol) are at reduced risk of dementia and ‘cognitive decline’ in later life. This evidence appears, at first sight, to contradict the idea that cholesterol has an important and critical role to play to brain function. However, one problem with this line of evidence is that it is subject to what is known as the ‘healthy user effect’.
Basically, what this means is that people who take statins are likely to be inherently healthier than those who do not. Not because they are taking statins, but because they are, say, more health conscious, and do not have a pre-existing medical condition which precludes them from taking statins. Because of the healthy user effect, we can draw no firm conclusions about this sort of evidence.
A recent review published in the Journal of Alzheimer’s disease [1] makes the point that in clinical studies in which people are treated with statins, no improvements in brain function in later life have been noted. This issue was actually reviewed back in 2009 [2]. In two well-designed studies which involved over 26,000 people, treatment with statins was not found to benefit brain function. The author of the review in the Journal of Alzheimer’s disease points out that lowering cholesterol levels may actually impair brain functioning, at least in part because of the role that it plays in the synapses.
There is at least some evidence for this in the form of a study which linked lower cholesterol levels in men with heightened risk of depression [3]. This study cannot be used to conclude that low cholesterol causes depression, but the finding is suspicious nonetheless. In a review of the literature, it was concluded that: “low cholesterol levels in serum are associated and related to different neuropsychiatric disorders. Lowered cholesterol levels seem likely to be linked to higher rates of early death, suicide, aggressive and violent behaviour, personality disorders, and possibly depression, dementia and penal confinement among young males.” [4].
The fact that mental symptoms such as memory loss and confusion can take a long time to come on is a concern, because many doctors will not suspect that statins may be causing symptoms that develop months or years after a drug is commenced. There’s a good chance, therefore, that many problems genuinely induced by statins will go undetected. In other words, such mental problems may not be as rare as the FDA and many medical practitioners think.
And what of the benefits of statins? Just to remind ourselves, many individuals need to take statins for several years for one, say, to avoid having a heart attack or stroke. What this means, is that the vast majority of people who take statins will not benefit from them at all. Also, the majority of people who take statins are essentially healthy (no history of, say, heart disease or stroke). In these people, statins do not reduce overall risk of death over time. What this means is that for the great majority of people, taking statins will not extend their life by a single day.
The new guidelines issued by the FDA only serve, I think, to remind us that risk-benefit ratio of statins is not so stacked in favour of benefit as we have been led to believe.
References:
1. Vilet PV. Cholesterol and Late-Life Cognitive Decline. J Alzheimers Dis 2012 Jan 20. [Epub ahead of print]
2. Mc Guinness B, et al. Statins for the prevention of dementia. Cochrane Database Syst Rev. 2009 Apr 15;(2):CD003160.
3. Ancelin ML, et al. Gender and genotype modulation of the association between lipid levels and depressive symptomatology in community-dwelling elderly (the ESPRIT study). Biol Psychiatry 2010;68(2):125-32
4. Martinez-Carpio PA, et al. Relation between cholesterol levels and neuropsychiatric disorders. Rev Neurol 2009;48(5):261-4
